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13196026eb
UglifyJS/lib/compress.js
Flamefire 13196026eb Use AST.Node instead of AST_Node
2018-06-13 12:50:54 +02:00

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/***********************************************************************
A JavaScript tokenizer / parser / beautifier / compressor.
https://github.com/mishoo/UglifyJS2
-------------------------------- (C) ---------------------------------
Author: Mihai Bazon
<mihai.bazon@gmail.com>
http://mihai.bazon.net/blog
Distributed under the BSD license:
Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above
copyright notice, this list of conditions and the following
disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials
provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
***********************************************************************/
"use strict";
var utils = require("./utils");
var member = utils.member;
var defaults = utils.defaults;
var merge = utils.merge;
var noop = utils.noop;
var return_false = utils.return_false;
var return_true = utils.return_true;
var return_this = utils.return_this;
var return_null = utils.return_null;
var string_template = utils.string_template;
var remove = utils.remove;
var makePredicate = utils.makePredicate;
var all = utils.all;
var Dictionary = utils.Dictionary;
var HOP = utils.HOP;
var MAP = utils.MAP;
var AST = require("./ast");
var TreeTransformer = AST.TreeTransformer;
var TreeWalker = AST.TreeWalker;
var first_in_statement = AST.first_in_statement;
var walk_body = AST.walk_body;
var parse = require("./parse");
var is_identifier_string = parse.is_identifier_string;
var JS_Parse_Error = parse.JS_Parse_Error;
var PRECEDENCE = parse.PRECEDENCE;
var parse = parse.parse;
var OutputStream = require("./output").OutputStream;
require("./scope")
function Compressor(options, false_by_default) {
if (!(this instanceof Compressor))
return new Compressor(options, false_by_default);
TreeTransformer.call(this, this.before, this.after);
this.options = defaults(options, {
arguments : !false_by_default,
booleans : !false_by_default,
collapse_vars : !false_by_default,
comparisons : !false_by_default,
conditionals : !false_by_default,
dead_code : !false_by_default,
drop_console : false,
drop_debugger : !false_by_default,
evaluate : !false_by_default,
expression : false,
global_defs : {},
hoist_funs : false,
hoist_props : !false_by_default,
hoist_vars : false,
ie8 : false,
if_return : !false_by_default,
inline : !false_by_default,
join_vars : !false_by_default,
keep_fargs : true,
keep_fnames : false,
keep_infinity : false,
loops : !false_by_default,
negate_iife : !false_by_default,
passes : 1,
properties : !false_by_default,
pure_getters : !false_by_default && "strict",
pure_funcs : null,
reduce_funcs : !false_by_default,
reduce_vars : !false_by_default,
sequences : !false_by_default,
side_effects : !false_by_default,
switches : !false_by_default,
top_retain : null,
toplevel : !!(options && options["top_retain"]),
typeofs : !false_by_default,
unsafe : false,
unsafe_comps : false,
unsafe_Function: false,
unsafe_math : false,
unsafe_proto : false,
unsafe_regexp : false,
unsafe_undefined: false,
unused : !false_by_default,
warnings : false,
}, true);
var global_defs = this.options["global_defs"];
if (typeof global_defs == "object") for (var key in global_defs) {
if (/^@/.test(key) && HOP(global_defs, key)) {
global_defs[key.slice(1)] = parse(global_defs[key], {
expression: true
});
}
}
if (this.options["inline"] === true) this.options["inline"] = 3;
var pure_funcs = this.options["pure_funcs"];
if (typeof pure_funcs == "function") {
this.pure_funcs = pure_funcs;
} else {
this.pure_funcs = pure_funcs ? function(node) {
return pure_funcs.indexOf(node.expression.print_to_string()) < 0;
} : return_true;
}
var top_retain = this.options["top_retain"];
if (top_retain instanceof RegExp) {
this.top_retain = function(def) {
return top_retain.test(def.name);
};
} else if (typeof top_retain == "function") {
this.top_retain = top_retain;
} else if (top_retain) {
if (typeof top_retain == "string") {
top_retain = top_retain.split(/,/);
}
this.top_retain = function(def) {
return top_retain.indexOf(def.name) >= 0;
};
}
var toplevel = this.options["toplevel"];
this.toplevel = typeof toplevel == "string" ? {
funcs: /funcs/.test(toplevel),
vars: /vars/.test(toplevel)
} : {
funcs: toplevel,
vars: toplevel
};
var sequences = this.options["sequences"];
this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
this.warnings_produced = {};
}
Compressor.prototype = new TreeTransformer;
merge(Compressor.prototype, {
option: function(key) { return this.options[key] },
exposed: function(def) {
if (def.global) for (var i = 0, len = def.orig.length; i < len; i++)
if (!this.toplevel[def.orig[i] instanceof AST.SymbolDefun ? "funcs" : "vars"])
return true;
return false;
},
compress: function(node) {
if (this.option("expression")) {
node.process_expression(true);
}
var passes = +this.options.passes || 1;
var min_count = 1 / 0;
var stopping = false;
var mangle = { ie8: this.option("ie8") };
for (var pass = 0; pass < passes; pass++) {
node.figure_out_scope(mangle);
if (pass > 0 || this.option("reduce_vars"))
node.reset_opt_flags(this);
node = node.transform(this);
if (passes > 1) {
var count = 0;
node.walk(new TreeWalker(function() {
count++;
}));
this.info("pass " + pass + ": last_count: " + min_count + ", count: " + count);
if (count < min_count) {
min_count = count;
stopping = false;
} else if (stopping) {
break;
} else {
stopping = true;
}
}
}
if (this.option("expression")) {
node.process_expression(false);
}
return node;
},
info: function() {
if (this.options.warnings == "verbose") {
AST.Node.warn.apply(AST.Node, arguments);
}
},
warn: function(text, props) {
if (this.options.warnings) {
// only emit unique warnings
var message = string_template(text, props);
if (!(message in this.warnings_produced)) {
this.warnings_produced[message] = true;
AST.Node.warn.apply(AST.Node, arguments);
}
}
},
clear_warnings: function() {
this.warnings_produced = {};
},
before: function(node, descend, in_list) {
if (node._squeezed) return node;
var is_scope = node instanceof AST.Scope;
if (is_scope) {
node.hoist_properties(this);
node.hoist_declarations(this);
}
// Before https://github.com/mishoo/UglifyJS2/pull/1602 AST.Node.optimize()
// would call AST.Node.transform() if a different instance of AST.Node is
// produced after OPT().
// This corrupts TreeWalker.stack, which cause AST look-ups to malfunction.
// Migrate and defer all children's AST.Node.transform() to below, which
// will now happen after this parent AST.Node has been properly substituted
// thus gives a consistent AST snapshot.
descend(node, this);
// Existing code relies on how AST.Node.optimize() worked, and omitting the
// following replacement call would result in degraded efficiency of both
// output and performance.
descend(node, this);
var opt = node.optimize(this);
if (is_scope) {
opt.drop_unused(this);
descend(opt, this);
}
if (opt === node) opt._squeezed = true;
return opt;
}
});
(function(OPT) {
OPT(AST.Node, function(self, compressor) {
return self;
});
AST.Node.DEFMETHOD("equivalent_to", function(node) {
return this.TYPE == node.TYPE && this.print_to_string() == node.print_to_string();
});
AST.Scope.DEFMETHOD("process_expression", function(insert, compressor) {
var self = this;
var tt = new TreeTransformer(function(node) {
if (insert && node instanceof AST.SimpleStatement) {
return make_node(AST.Return, node, {
value: node.body
});
}
if (!insert && node instanceof AST.Return) {
if (compressor) {
var value = node.value && node.value.drop_side_effect_free(compressor, true);
return value ? make_node(AST.SimpleStatement, node, {
body: value
}) : make_node(AST.EmptyStatement, node);
}
return make_node(AST.SimpleStatement, node, {
body: node.value || make_node(AST.UnaryPrefix, node, {
operator: "void",
expression: make_node(AST.Number, node, {
value: 0
})
})
});
}
if (node instanceof AST.Lambda && node !== self) {
return node;
}
if (node instanceof AST.Block) {
var index = node.body.length - 1;
if (index >= 0) {
node.body[index] = node.body[index].transform(tt);
}
} else if (node instanceof AST.If) {
node.body = node.body.transform(tt);
if (node.alternative) {
node.alternative = node.alternative.transform(tt);
}
} else if (node instanceof AST.With) {
node.body = node.body.transform(tt);
}
return node;
});
self.transform(tt);
});
function read_property(obj, key) {
key = get_value(key);
if (key instanceof AST.Node) return;
var value;
if (obj instanceof AST.Array) {
var elements = obj.elements;
if (key == "length") return make_node_from_constant(elements.length, obj);
if (typeof key == "number" && key in elements) value = elements[key];
} else if (obj instanceof AST.Object) {
key = "" + key;
var props = obj.properties;
for (var i = props.length; --i >= 0;) {
var prop = props[i];
if (!(prop instanceof AST.ObjectKeyVal)) return;
if (!value && props[i].key === key) value = props[i].value;
}
}
return value instanceof AST.SymbolRef && value.fixed_value() || value;
}
function is_modified(compressor, tw, node, value, level, immutable) {
var parent = tw.parent(level);
var lhs = is_lhs(node, parent);
if (lhs) return lhs;
if (!immutable
&& parent instanceof AST.Call
&& parent.expression === node
&& !parent.is_expr_pure(compressor)
&& (!(value instanceof AST.Function)
|| !(parent instanceof AST.New) && value.contains_this())) {
return true;
}
if (parent instanceof AST.Array) {
return is_modified(compressor, tw, parent, parent, level + 1);
}
if (parent instanceof AST.ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1);
return is_modified(compressor, tw, obj, obj, level + 2);
}
if (parent instanceof AST.PropAccess && parent.expression === node) {
var prop = read_property(value, parent.property);
return !immutable && is_modified(compressor, tw, parent, prop, level + 1);
}
}
(function(def) {
def(AST.Node, noop);
function reset_def(tw, compressor, def) {
def.assignments = 0;
def.chained = false;
def.direct_access = false;
def.escaped = false;
if (def.scope.pinned()) {
def.fixed = false;
} else if (!compressor.exposed(def)) {
def.fixed = def.init;
} else {
def.fixed = false;
}
if (def.fixed instanceof AST.Defun && !all(def.references, function(ref) {
var scope = ref.scope;
do {
if (def.scope === scope) return true;
} while (scope instanceof AST.Function && (scope = scope.parent_scope));
})) {
tw.defun_ids[def.id] = false;
}
def.recursive_refs = 0;
def.references = [];
def.should_replace = undefined;
def.single_use = undefined;
}
function reset_variables(tw, compressor, scope) {
scope.variables.each(function(def) {
reset_def(tw, compressor, def);
if (def.fixed === null) {
def.safe_ids = tw.safe_ids;
mark(tw, def, true);
} else if (def.fixed) {
tw.loop_ids[def.id] = tw.in_loop;
mark(tw, def, true);
}
});
scope.may_call_this = function() {
scope.may_call_this = noop;
if (!scope.contains_this()) return;
scope.functions.each(function(def) {
if (def.init instanceof AST.Defun && !(def.id in tw.defun_ids)) {
tw.defun_ids[def.id] = false;
}
});
};
}
function mark_defun(tw, def) {
if (def.id in tw.defun_ids) {
var marker = tw.defun_ids[def.id];
if (!marker) return;
var visited = tw.defun_visited[def.id];
if (marker === tw.safe_ids) {
if (!visited) return def.fixed;
} else if (visited) {
def.init.enclosed.forEach(function(d) {
if (def.init.variables.get(d.name) === d) return;
if (!safe_to_read(tw, d)) d.fixed = false;
});
} else {
tw.defun_ids[def.id] = false;
}
} else {
if (!tw.in_loop) {
tw.defun_ids[def.id] = tw.safe_ids;
return def.fixed;
}
tw.defun_ids[def.id] = false;
}
}
function walk_defuns(tw, scope) {
scope.functions.each(function(def) {
if (def.init instanceof AST.Defun && !tw.defun_visited[def.id]) {
tw.defun_ids[def.id] = tw.safe_ids;
def.init.walk(tw);
}
});
}
function push(tw) {
tw.safe_ids = Object.create(tw.safe_ids);
}
function pop(tw) {
tw.safe_ids = Object.getPrototypeOf(tw.safe_ids);
}
function mark(tw, def, safe) {
tw.safe_ids[def.id] = safe;
}
function safe_to_read(tw, def) {
if (tw.safe_ids[def.id]) {
if (def.fixed == null) {
var orig = def.orig[0];
if (orig instanceof AST.SymbolFunarg || orig.name == "arguments") return false;
def.fixed = make_node(AST.Undefined, orig);
}
return true;
}
return def.fixed instanceof AST.Defun;
}
function safe_to_assign(tw, def, scope, value) {
if (def.fixed === undefined) return true;
if (def.fixed === null && def.safe_ids) {
def.safe_ids[def.id] = false;
delete def.safe_ids;
return true;
}
if (!HOP(tw.safe_ids, def.id)) return false;
if (!safe_to_read(tw, def)) return false;
if (def.fixed === false) return false;
if (def.fixed != null && (!value || def.references.length > def.assignments)) return false;
if (def.fixed instanceof AST.Defun) {
return value instanceof AST.Node && def.fixed.parent_scope === scope;
}
return all(def.orig, function(sym) {
return !(sym instanceof AST.SymbolDefun
|| sym instanceof AST.SymbolLambda);
});
}
function ref_once(tw, compressor, def) {
return compressor.option("unused")
&& !def.scope.pinned()
&& def.references.length - def.recursive_refs == 1
&& tw.loop_ids[def.id] === tw.in_loop;
}
function is_immutable(value) {
if (!value) return false;
return value.is_constant()
|| value instanceof AST.Lambda
|| value instanceof AST.This;
}
function mark_escaped(tw, d, scope, node, value, level, depth) {
var parent = tw.parent(level);
if (value && value.is_constant()) return;
if (parent instanceof AST.Assign && parent.operator == "=" && node === parent.right
|| parent instanceof AST.Call && (node !== parent.expression || parent instanceof AST.New)
|| parent instanceof AST.Exit && node === parent.value && node.scope !== d.scope
|| parent instanceof AST.VarDef && node === parent.value) {
if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1;
if (!d.escaped || d.escaped > depth) d.escaped = depth;
return;
} else if (parent instanceof AST.Array
|| parent instanceof AST.Binary && lazy_op[parent.operator]
|| parent instanceof AST.Conditional && node !== parent.condition
|| parent instanceof AST.Sequence && node === parent.tail_node()) {
mark_escaped(tw, d, scope, parent, parent, level + 1, depth);
} else if (parent instanceof AST.ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1);
mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
} else if (parent instanceof AST.PropAccess && node === parent.expression) {
value = read_property(value, parent.property);
mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
if (value) return;
}
if (level > 0) return;
if (parent instanceof AST.Sequence && node !== parent.tail_node()) return;
if (parent instanceof AST.SimpleStatement) return;
d.direct_access = true;
}
var suppressor = new TreeWalker(function(node) {
if (!(node instanceof AST.Symbol)) return;
var d = node.definition();
if (!d) return;
if (node instanceof AST.SymbolRef) d.references.push(node);
d.fixed = false;
});
def(AST.Accessor, function(tw, descend, compressor) {
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST.Assign, function(tw, descend, compressor) {
var node = this;
var sym = node.left;
if (!(sym instanceof AST.SymbolRef)) return;
var d = sym.definition();
var fixed = d.fixed;
if (!fixed && node.operator != "=") return;
if (!safe_to_assign(tw, d, sym.scope, node.right)) return;
var eq = node.operator == "=";
var value = eq ? node.right : node;
if (is_modified(compressor, tw, node, value, 0)) return;
d.references.push(sym);
d.assignments++;
if (!eq) d.chained = true;
d.fixed = eq ? function() {
return node.right;
} : function() {
return make_node(AST.Binary, node, {
operator: node.operator.slice(0, -1),
left: fixed instanceof AST.Node ? fixed : fixed(),
right: node.right
});
};
mark(tw, d, false);
node.right.walk(tw);
mark(tw, d, true);
mark_escaped(tw, d, sym.scope, node, value, 0, 1);
return true;
});
def(AST.Binary, function(tw) {
if (!lazy_op[this.operator]) return;
this.left.walk(tw);
push(tw);
this.right.walk(tw);
pop(tw);
return true;
});
def(AST.Call, function(tw, descend) {
tw.find_parent(AST.Scope).may_call_this();
var exp = this.expression;
if (!(exp instanceof AST.SymbolRef)) return;
var def = exp.definition();
if (!(def.fixed instanceof AST.Defun)) return;
var defun = mark_defun(tw, def);
if (!defun) return;
descend();
defun.walk(tw);
return true;
});
def(AST.Case, function(tw) {
push(tw);
this.expression.walk(tw);
pop(tw);
push(tw);
walk_body(this, tw);
pop(tw);
return true;
});
def(AST.Conditional, function(tw) {
this.condition.walk(tw);
push(tw);
this.consequent.walk(tw);
pop(tw);
push(tw);
this.alternative.walk(tw);
pop(tw);
return true;
});
def(AST.Default, function(tw, descend) {
push(tw);
descend();
pop(tw);
return true;
});
def(AST.Defun, function(tw, descend, compressor) {
var id = this.name.definition().id;
if (tw.defun_visited[id]) return true;
if (tw.defun_ids[id] !== tw.safe_ids) return true;
tw.defun_visited[id] = true;
this.inlined = false;
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST.Do, function(tw) {
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
this.body.walk(tw);
if (has_break_or_continue(this)) {
pop(tw);
push(tw);
}
this.condition.walk(tw);
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST.For, function(tw) {
if (this.init) this.init.walk(tw);
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
if (this.condition) this.condition.walk(tw);
this.body.walk(tw);
if (this.step) {
if (has_break_or_continue(this)) {
pop(tw);
push(tw);
}
this.step.walk(tw);
}
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST.ForIn, function(tw) {
this.init.walk(suppressor);
this.object.walk(tw);
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
this.body.walk(tw);
pop(tw);
tw.in_loop = saved_loop;
return true;
});
def(AST.Function, function(tw, descend, compressor) {
var node = this;
node.inlined = false;
push(tw);
reset_variables(tw, compressor, node);
var iife;
if (!node.name
&& (iife = tw.parent()) instanceof AST.Call
&& iife.expression === node) {
// Virtually turn IIFE parameters into variable definitions:
// (function(a,b) {...})(c,d) => (function() {var a=c,b=d; ...})()
// So existing transformation rules can work on them.
node.argnames.forEach(function(arg, i) {
var d = arg.definition();
if (!node.uses_arguments && d.fixed === undefined) {
d.fixed = function() {
return iife.args[i] || make_node(AST.Undefined, iife);
};
tw.loop_ids[d.id] = tw.in_loop;
mark(tw, d, true);
} else {
d.fixed = false;
}
});
}
descend();
pop(tw);
walk_defuns(tw, node);
return true;
});
def(AST.If, function(tw) {
this.condition.walk(tw);
push(tw);
this.body.walk(tw);
pop(tw);
if (this.alternative) {
push(tw);
this.alternative.walk(tw);
pop(tw);
}
return true;
});
def(AST.LabeledStatement, function(tw) {
push(tw);
this.body.walk(tw);
pop(tw);
return true;
});
def(AST.SymbolCatch, function() {
this.definition().fixed = false;
});
def(AST.SymbolRef, function(tw, descend, compressor) {
var d = this.definition();
d.references.push(this);
if (d.references.length == 1
&& !d.fixed
&& d.orig[0] instanceof AST.SymbolDefun) {
tw.loop_ids[d.id] = tw.in_loop;
}
var value;
if (d.fixed === undefined || !safe_to_read(tw, d) || d.single_use == "m") {
d.fixed = false;
} else if (d.fixed) {
value = this.fixed_value();
if (value instanceof AST.Lambda && recursive_ref(tw, d)) {
d.recursive_refs++;
} else if (value && ref_once(tw, compressor, d)) {
d.single_use = value instanceof AST.Lambda && !value.pinned()
|| d.scope === this.scope && value.is_constant_expression();
} else {
d.single_use = false;
}
if (is_modified(compressor, tw, this, value, 0, is_immutable(value))) {
if (d.single_use) {
d.single_use = "m";
} else {
d.fixed = false;
}
}
}
mark_escaped(tw, d, this.scope, this, value, 0, 1);
var parent;
if (d.fixed instanceof AST.Defun
&& !((parent = tw.parent()) instanceof AST.Call && parent.expression === this)) {
var defun = mark_defun(tw, d);
if (defun) defun.walk(tw);
}
});
def(AST.Toplevel, function(tw, descend, compressor) {
this.globals.each(function(def) {
reset_def(tw, compressor, def);
});
push(tw);
reset_variables(tw, compressor, this);
descend();
pop(tw);
walk_defuns(tw, this);
return true;
});
def(AST.Try, function(tw) {
push(tw);
walk_body(this, tw);
pop(tw);
if (this.bcatch) {
push(tw);
this.bcatch.walk(tw);
pop(tw);
}
if (this.bfinally) this.bfinally.walk(tw);
return true;
});
def(AST.Unary, function(tw, descend) {
var node = this;
if (node.operator != "++" && node.operator != "--") return;
var exp = node.expression;
if (!(exp instanceof AST.SymbolRef)) return;
var d = exp.definition();
var fixed = d.fixed;
if (!fixed) return;
if (!safe_to_assign(tw, d, exp.scope, true)) return;
d.references.push(exp);
d.assignments++;
d.chained = true;
d.fixed = function() {
return make_node(AST.Binary, node, {
operator: node.operator.slice(0, -1),
left: make_node(AST.UnaryPrefix, node, {
operator: "+",
expression: fixed instanceof AST.Node ? fixed : fixed()
}),
right: make_node(AST.Number, node, {
value: 1
})
});
};
mark(tw, d, true);
return true;
});
def(AST.VarDef, function(tw, descend) {
var node = this;
var d = node.name.definition();
if (node.value) {
if (safe_to_assign(tw, d, node.name.scope, node.value)) {
d.fixed = function() {
return node.value;
};
tw.loop_ids[d.id] = tw.in_loop;
mark(tw, d, false);
descend();
mark(tw, d, true);
return true;
} else {
d.fixed = false;
}
}
});
def(AST.While, function(tw, descend) {
var saved_loop = tw.in_loop;
tw.in_loop = this;
push(tw);
descend();
pop(tw);
tw.in_loop = saved_loop;
return true;
});
})(function(node, func) {
node.DEFMETHOD("reduce_vars", func);
});
AST.Toplevel.DEFMETHOD("reset_opt_flags", function(compressor) {
var tw = new TreeWalker(compressor.option("reduce_vars") ? function(node, descend) {
node._squeezed = false;
node._optimized = false;
return node.reduce_vars(tw, descend, compressor);
} : function(node) {
node._squeezed = false;
node._optimized = false;
});
// Flow control for visiting `AST.Defun`s
tw.defun_ids = Object.create(null);
tw.defun_visited = Object.create(null);
// Record the loop body in which `AST.SymbolDeclaration` is first encountered
tw.in_loop = null;
tw.loop_ids = Object.create(null);
// Stack of look-up tables to keep track of whether a `SymbolDef` has been
// properly assigned before use:
// - `push()` & `pop()` when visiting conditional branches
// - backup & restore via `save_ids` when visiting out-of-order sections
tw.safe_ids = Object.create(null);
this.walk(tw);
});
AST.Symbol.DEFMETHOD("fixed_value", function() {
var fixed = this.definition().fixed;
if (!fixed || fixed instanceof AST.Node) return fixed;
return fixed();
});
AST.SymbolRef.DEFMETHOD("is_immutable", function() {
var orig = this.definition().orig;
return orig.length == 1 && orig[0] instanceof AST.SymbolLambda;
});
function is_lhs_read_only(lhs) {
if (lhs instanceof AST.This) return true;
if (lhs instanceof AST.SymbolRef) return lhs.definition().orig[0] instanceof AST.SymbolLambda;
if (lhs instanceof AST.PropAccess) {
lhs = lhs.expression;
if (lhs instanceof AST.SymbolRef) {
if (lhs.is_immutable()) return false;
lhs = lhs.fixed_value();
}
if (!lhs) return true;
if (lhs.is_constant()) return true;
return is_lhs_read_only(lhs);
}
return false;
}
function find_variable(compressor, name) {
var scope, i = 0;
while (scope = compressor.parent(i++)) {
if (scope instanceof AST.Scope) break;
if (scope instanceof AST.Catch) {
scope = scope.argname.definition().scope;
break;
}
}
return scope.find_variable(name);
}
function make_node(ctor, orig, props) {
if (!props) props = {};
if (orig) {
if (!props.start) props.start = orig.start;
if (!props.end) props.end = orig.end;
}
return new ctor(props);
}
function make_sequence(orig, expressions) {
if (expressions.length == 1) return expressions[0];
return make_node(AST.Sequence, orig, {
expressions: expressions.reduce(merge_sequence, [])
});
}
function make_node_from_constant(val, orig) {
switch (typeof val) {
case "string":
return make_node(AST.String, orig, {
value: val
});
case "number":
if (isNaN(val)) return make_node(AST.NaN, orig);
if (isFinite(val)) {
return 1 / val < 0 ? make_node(AST.UnaryPrefix, orig, {
operator: "-",
expression: make_node(AST.Number, orig, { value: -val })
}) : make_node(AST.Number, orig, { value: val });
}
return val < 0 ? make_node(AST.UnaryPrefix, orig, {
operator: "-",
expression: make_node(AST.Infinity, orig)
}) : make_node(AST.Infinity, orig);
case "boolean":
return make_node(val ? AST.True : AST.False, orig);
case "undefined":
return make_node(AST.Undefined, orig);
default:
if (val === null) {
return make_node(AST.Null, orig, { value: null });
}
if (val instanceof RegExp) {
return make_node(AST.RegExp, orig, { value: val });
}
throw new Error(string_template("Can't handle constant of type: {type}", {
type: typeof val
}));
}
}
function needs_unbinding(compressor, val) {
return val instanceof AST.PropAccess
|| compressor.has_directive("use strict")
&& is_undeclared_ref(val)
&& val.name == "eval";
}
// we shouldn't compress (1,func)(something) to
// func(something) because that changes the meaning of
// the func (becomes lexical instead of global).
function maintain_this_binding(compressor, parent, orig, val) {
if (parent instanceof AST.UnaryPrefix && parent.operator == "delete"
|| parent.TYPE == "Call" && parent.expression === orig && needs_unbinding(compressor, val)) {
return make_sequence(orig, [ make_node(AST.Number, orig, { value: 0 }), val ]);
}
return val;
}
function merge_sequence(array, node) {
if (node instanceof AST.Sequence) {
array.push.apply(array, node.expressions);
} else {
array.push(node);
}
return array;
}
function as_statement_array(thing) {
if (thing === null) return [];
if (thing instanceof AST.BlockStatement) return thing.body;
if (thing instanceof AST.EmptyStatement) return [];
if (thing instanceof AST.Statement) return [ thing ];
throw new Error("Can't convert thing to statement array");
}
function is_empty(thing) {
if (thing === null) return true;
if (thing instanceof AST.EmptyStatement) return true;
if (thing instanceof AST.BlockStatement) return thing.body.length == 0;
return false;
}
function loop_body(x) {
if (x instanceof AST.IterationStatement) {
return x.body instanceof AST.BlockStatement ? x.body : x;
}
return x;
}
function root_expr(prop) {
while (prop instanceof AST.PropAccess) prop = prop.expression;
return prop;
}
function is_iife_call(node) {
if (node.TYPE != "Call") return false;
return node.expression instanceof AST.Function || is_iife_call(node.expression);
}
function is_undeclared_ref(node) {
return node instanceof AST.SymbolRef && node.definition().undeclared;
}
var global_names = makePredicate("Array Boolean clearInterval clearTimeout console Date decodeURI decodeURIComponent encodeURI encodeURIComponent Error escape eval EvalError Function isFinite isNaN JSON Math Number parseFloat parseInt RangeError ReferenceError RegExp Object setInterval setTimeout String SyntaxError TypeError unescape URIError");
AST.SymbolRef.DEFMETHOD("is_declared", function(compressor) {
return !this.definition().undeclared
|| compressor.option("unsafe") && global_names[this.name];
});
var identifier_atom = makePredicate("Infinity NaN undefined");
function is_identifier_atom(node) {
return node instanceof AST.Infinity
|| node instanceof AST.NaN
|| node instanceof AST.Undefined;
}
function tighten_body(statements, compressor) {
var in_loop, in_try, scope;
find_loop_scope_try();
var CHANGED, max_iter = 10;
do {
CHANGED = false;
eliminate_spurious_blocks(statements);
if (compressor.option("dead_code")) {
eliminate_dead_code(statements, compressor);
}
if (compressor.option("if_return")) {
handle_if_return(statements, compressor);
}
if (compressor.sequences_limit > 0) {
sequencesize(statements, compressor);
sequencesize_2(statements, compressor);
}
if (compressor.option("join_vars")) {
join_consecutive_vars(statements);
}
if (compressor.option("collapse_vars")) {
collapse(statements, compressor);
}
} while (CHANGED && max_iter-- > 0);
function find_loop_scope_try() {
var node = compressor.self(), level = 0;
do {
if (node instanceof AST.Catch || node instanceof AST.Finally) {
level++;
} else if (node instanceof AST.IterationStatement) {
in_loop = true;
} else if (node instanceof AST.Scope) {
scope = node;
break;
} else if (node instanceof AST.Try) {
in_try = true;
}
} while (node = compressor.parent(level++));
}
// Search from right to left for assignment-like expressions:
// - `var a = x;`
// - `a = x;`
// - `++a`
// For each candidate, scan from left to right for first usage, then try
// to fold assignment into the site for compression.
// Will not attempt to collapse assignments into or past code blocks
// which are not sequentially executed, e.g. loops and conditionals.
function collapse(statements, compressor) {
if (scope.pinned()) return statements;
var args;
var candidates = [];
var stat_index = statements.length;
var scanner = new TreeTransformer(function(node) {
if (abort) return node;
// Skip nodes before `candidate` as quickly as possible
if (!hit) {
if (node !== hit_stack[hit_index]) return node;
hit_index++;
if (hit_index < hit_stack.length) return handle_custom_scan_order(node);
hit = true;
stop_after = find_stop(node, 0);
if (stop_after === node) abort = true;
return node;
}
// Stop immediately if these node types are encountered
var parent = scanner.parent();
if (should_stop(node, parent)) {
abort = true;
return node;
}
// Stop only if candidate is found within conditional branches
if (!stop_if_hit && in_conditional(node, parent)) {
stop_if_hit = parent;
}
// Replace variable with assignment when found
var hit_lhs, hit_rhs;
if (can_replace
&& !(node instanceof AST.SymbolDeclaration)
&& (scan_lhs && (hit_lhs = lhs.equivalent_to(node))
|| scan_rhs && (hit_rhs = scan_rhs(node, this)))) {
if (stop_if_hit && (hit_rhs || !lhs_local || !replace_all)) {
abort = true;
return node;
}
if (is_lhs(node, parent)) {
if (value_def) replaced++;
return node;
} else {
replaced++;
if (value_def && candidate instanceof AST.VarDef) return node;
}
CHANGED = abort = true;
compressor.info("Collapsing {name} [{file}:{line},{col}]", {
name: node.print_to_string(),
file: node.start.file,
line: node.start.line,
col: node.start.col
});
if (candidate instanceof AST.UnaryPostfix) {
return make_node(AST.UnaryPrefix, candidate, candidate);
}
if (candidate instanceof AST.VarDef) {
var def = candidate.name.definition();
if (def.references.length - def.replaced == 1 && !compressor.exposed(def)) {
def.replaced++;
return maintain_this_binding(compressor, parent, node, candidate.value);
}
return make_node(AST.Assign, candidate, {
operator: "=",
left: make_node(AST.SymbolRef, candidate.name, candidate.name),
right: candidate.value
});
}
candidate.write_only = false;
return candidate;
}
// These node types have child nodes that execute sequentially,
// but are otherwise not safe to scan into or beyond them.
var sym;
if (is_last_node(node, parent) || may_throw(node)) {
stop_after = node;
if (node instanceof AST.Scope) abort = true;
}
return handle_custom_scan_order(node);
}, function(node) {
if (abort) return;
if (stop_after === node) abort = true;
if (stop_if_hit === node) stop_if_hit = null;
});
var multi_replacer = new TreeTransformer(function(node) {
if (abort) return node;
// Skip nodes before `candidate` as quickly as possible
if (!hit) {
if (node !== hit_stack[hit_index]) return node;
hit_index++;
if (hit_index < hit_stack.length) return;
hit = true;
return node;
}
// Replace variable when found
if (node instanceof AST.SymbolRef
&& node.name == def.name) {
if (!--replaced) abort = true;
if (is_lhs(node, multi_replacer.parent())) return node;
def.replaced++;
value_def.replaced--;
return candidate.value.clone();
}
// Skip (non-executed) functions and (leading) default case in switch statements
if (node instanceof AST.Default || node instanceof AST.Scope) return node;
});
while (--stat_index >= 0) {
// Treat parameters as collapsible in IIFE, i.e.
// function(a, b){ ... }(x());
// would be translated into equivalent assignments:
// var a = x(), b = undefined;
if (stat_index == 0 && compressor.option("unused")) extract_args();
// Find collapsible assignments
var hit_stack = [];
extract_candidates(statements[stat_index]);
while (candidates.length > 0) {
hit_stack = candidates.pop();
var hit_index = 0;
var candidate = hit_stack[hit_stack.length - 1];
var value_def = null;
var stop_after = null;
var stop_if_hit = null;
var lhs = get_lhs(candidate);
var rhs = get_rhs(candidate);
var side_effects = lhs && lhs.has_side_effects(compressor);
var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs);
var scan_rhs = rhs && foldable(rhs);
if (!scan_lhs && !scan_rhs) continue;
// Locate symbols which may execute code outside of scanning range
var lvalues = get_lvalues(candidate);
var lhs_local = is_lhs_local(lhs);
if (!side_effects) side_effects = value_has_side_effects(candidate);
var replace_all = replace_all_symbols();
var may_throw = candidate.may_throw(compressor) ? in_try ? function(node) {
return node.has_side_effects(compressor);
} : side_effects_external : return_false;
var funarg = candidate.name instanceof AST.SymbolFunarg;
var hit = funarg;
var abort = false, replaced = 0, can_replace = !args || !hit;
if (!can_replace) {
for (var j = compressor.self().argnames.lastIndexOf(candidate.name) + 1; !abort && j < args.length; j++) {
args[j].transform(scanner);
}
can_replace = true;
}
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(scanner);
}
if (value_def) {
var def = candidate.name.definition();
if (abort && def.references.length - def.replaced > replaced) replaced = false;
else {
abort = false;
hit_index = 0;
hit = funarg;
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(multi_replacer);
}
value_def.single_use = false;
}
}
if (replaced && !remove_candidate(candidate)) statements.splice(stat_index, 1);
}
}
function handle_custom_scan_order(node) {
// Skip (non-executed) functions
if (node instanceof AST.Scope) return node;
// Scan case expressions first in a switch statement
if (node instanceof AST.Switch) {
node.expression = node.expression.transform(scanner);
for (var i = 0, len = node.body.length; !abort && i < len; i++) {
var branch = node.body[i];
if (branch instanceof AST.Case) {
if (!hit) {
if (branch !== hit_stack[hit_index]) continue;
hit_index++;
}
branch.expression = branch.expression.transform(scanner);
if (!replace_all) break;
}
}
abort = true;
return node;
}
}
function should_stop(node, parent) {
if (parent instanceof AST.For) return node !== parent.init;
if (node instanceof AST.Assign) {
return node.operator != "=" && lhs.equivalent_to(node.left);
}
if (node instanceof AST.Call) {
return lhs instanceof AST.PropAccess && lhs.equivalent_to(node.expression);
}
if (node instanceof AST.Debugger) return true;
if (node instanceof AST.IterationStatement) return !(node instanceof AST.For);
if (node instanceof AST.LoopControl) return true;
if (node instanceof AST.Try) return true;
if (node instanceof AST.With) return true;
if (replace_all) return false;
return node instanceof AST.SymbolRef && !node.is_declared(compressor);
}
function in_conditional(node, parent) {
if (parent instanceof AST.Binary) return lazy_op[parent.operator] && parent.left !== node;
if (parent instanceof AST.Conditional) return parent.condition !== node;
return parent instanceof AST.If && parent.condition !== node;
}
function is_last_node(node, parent) {
if (node instanceof AST.Call) return true;
if (node instanceof AST.Exit) {
return side_effects || lhs instanceof AST.PropAccess || may_modify(lhs);
}
if (node instanceof AST.PropAccess) {
return side_effects || node.expression.may_throw_on_access(compressor);
}
if (node instanceof AST.SymbolRef) {
if (symbol_in_lvalues(node, parent)) {
return !parent || parent.operator != "=" || parent.left !== node;
}
return side_effects && may_modify(node);
}
if (node instanceof AST.This) return symbol_in_lvalues(node, parent);
if (node instanceof AST.VarDef) {
if (!node.value) return false;
return node.name.name in lvalues || side_effects && may_modify(node.name);
}
var sym = is_lhs(node.left, node);
if (sym && sym.name in lvalues) return true;
if (sym instanceof AST.PropAccess) return true;
}
function extract_args() {
var iife, fn = compressor.self();
if (fn instanceof AST.Function
&& !fn.name
&& !fn.uses_arguments
&& !fn.pinned()
&& (iife = compressor.parent()) instanceof AST.Call
&& iife.expression === fn) {
var fn_strict = compressor.has_directive("use strict");
if (fn_strict && !member(fn_strict, fn.body)) fn_strict = false;
var len = fn.argnames.length;
args = iife.args.slice(len);
var names = Object.create(null);
for (var i = len; --i >= 0;) {
var sym = fn.argnames[i];
var arg = iife.args[i];
args.unshift(make_node(AST.VarDef, sym, {
name: sym,
value: arg
}));
if (sym.name in names) continue;
names[sym.name] = true;
if (!arg) {
arg = make_node(AST.Undefined, sym).transform(compressor);
} else if (arg instanceof AST.Lambda && arg.pinned()) {
arg = null;
} else {
arg.walk(new TreeWalker(function(node) {
if (!arg) return true;
if (node instanceof AST.SymbolRef && fn.variables.has(node.name)) {
var s = node.definition().scope;
if (s !== scope) while (s = s.parent_scope) {
if (s === scope) return true;
}
arg = null;
}
if (node instanceof AST.This && (fn_strict || !this.find_parent(AST.Scope))) {
arg = null;
return true;
}
}));
}
if (arg) candidates.unshift([ make_node(AST.VarDef, sym, {
name: sym,
value: arg
}) ]);
}
}
}
function extract_candidates(expr) {
hit_stack.push(expr);
if (expr instanceof AST.Assign) {
candidates.push(hit_stack.slice());
extract_candidates(expr.right);
} else if (expr instanceof AST.Binary) {
extract_candidates(expr.left);
extract_candidates(expr.right);
} else if (expr instanceof AST.Call) {
extract_candidates(expr.expression);
expr.args.forEach(extract_candidates);
} else if (expr instanceof AST.Case) {
extract_candidates(expr.expression);
} else if (expr instanceof AST.Conditional) {
extract_candidates(expr.condition);
extract_candidates(expr.consequent);
extract_candidates(expr.alternative);
} else if (expr instanceof AST.Definitions) {
expr.definitions.forEach(extract_candidates);
} else if (expr instanceof AST.DWLoop) {
extract_candidates(expr.condition);
if (!(expr.body instanceof AST.Block)) {
extract_candidates(expr.body);
}
} else if (expr instanceof AST.Exit) {
if (expr.value) extract_candidates(expr.value);
} else if (expr instanceof AST.For) {
if (expr.init) extract_candidates(expr.init);
if (expr.condition) extract_candidates(expr.condition);
if (expr.step) extract_candidates(expr.step);
if (!(expr.body instanceof AST.Block)) {
extract_candidates(expr.body);
}
} else if (expr instanceof AST.ForIn) {
extract_candidates(expr.object);
if (!(expr.body instanceof AST.Block)) {
extract_candidates(expr.body);
}
} else if (expr instanceof AST.If) {
extract_candidates(expr.condition);
if (!(expr.body instanceof AST.Block)) {
extract_candidates(expr.body);
}
if (expr.alternative && !(expr.alternative instanceof AST.Block)) {
extract_candidates(expr.alternative);
}
} else if (expr instanceof AST.Sequence) {
expr.expressions.forEach(extract_candidates);
} else if (expr instanceof AST.SimpleStatement) {
extract_candidates(expr.body);
} else if (expr instanceof AST.Switch) {
extract_candidates(expr.expression);
expr.body.forEach(extract_candidates);
} else if (expr instanceof AST.Unary) {
if (expr.operator == "++" || expr.operator == "--") {
candidates.push(hit_stack.slice());
} else {
extract_candidates(expr.expression);
}
} else if (expr instanceof AST.VarDef) {
if (expr.value) {
var def = expr.name.definition();
if (def.references.length > def.replaced) {
candidates.push(hit_stack.slice());
}
extract_candidates(expr.value);
}
}
hit_stack.pop();
}
function find_stop(node, level, write_only) {
var parent = scanner.parent(level);
if (parent instanceof AST.Assign) {
if (write_only
&& !(parent.left instanceof AST.PropAccess
|| parent.left.name in lvalues)) {
return find_stop(parent, level + 1, write_only);
}
return node;
}
if (parent instanceof AST.Binary) {
if (write_only && (!lazy_op[parent.operator] || parent.left === node)) {
return find_stop(parent, level + 1, write_only);
}
return node;
}
if (parent instanceof AST.Call) return node;
if (parent instanceof AST.Case) return node;
if (parent instanceof AST.Conditional) {
if (write_only && parent.condition === node) {
return find_stop(parent, level + 1, write_only);
}
return node;
}
if (parent instanceof AST.Definitions) {
return find_stop(parent, level + 1, true);
}
if (parent instanceof AST.Exit) {
return write_only ? find_stop(parent, level + 1, write_only) : node;
}
if (parent instanceof AST.If) {
if (write_only && parent.condition === node) {
return find_stop(parent, level + 1, write_only);
}
return node;
}
if (parent instanceof AST.IterationStatement) return node;
if (parent instanceof AST.Sequence) {
return find_stop(parent, level + 1, parent.tail_node() !== node);
}
if (parent instanceof AST.SimpleStatement) {
return find_stop(parent, level + 1, true);
}
if (parent instanceof AST.Switch) return node;
if (parent instanceof AST.Unary) return node;
if (parent instanceof AST.VarDef) return node;
return null;
}
function mangleable_var(var_def) {
var value = var_def.value;
if (!(value instanceof AST.SymbolRef)) return;
if (value.name == "arguments") return;
var def = value.definition();
if (def.undeclared) return;
return value_def = def;
}
function get_lhs(expr) {
if (expr instanceof AST.VarDef) {
var def = expr.name.definition();
if (!member(expr.name, def.orig)) return;
var referenced = def.references.length - def.replaced;
var declared = def.orig.length - def.eliminated;
if (declared > 1 && !(expr.name instanceof AST.SymbolFunarg)
|| (referenced > 1 ? mangleable_var(expr) : !compressor.exposed(def))) {
return make_node(AST.SymbolRef, expr.name, expr.name);
}
} else {
return expr[expr instanceof AST.Assign ? "left" : "expression"];
}
}
function get_rhs(expr) {
if (!(candidate instanceof AST.Assign && candidate.operator == "=")) return;
return candidate.right;
}
function get_rvalue(expr) {
return expr[expr instanceof AST.Assign ? "right" : "value"];
}
function foldable(expr) {
if (expr instanceof AST.SymbolRef) {
var value = expr.evaluate(compressor);
if (value === expr) return rhs_exact_match;
return rhs_fuzzy_match(value, rhs_exact_match);
}
if (expr instanceof AST.This) return rhs_exact_match;
if (expr.is_truthy()) return rhs_fuzzy_match(true, return_false);
if (expr.is_constant()) {
return rhs_fuzzy_match(expr.evaluate(compressor), rhs_exact_match);
}
if (!(lhs instanceof AST.SymbolRef)) return false;
if (expr.has_side_effects(compressor)) return false;
var circular;
var def = lhs.definition();
expr.walk(new TreeWalker(function(node) {
if (circular) return true;
if (node instanceof AST.SymbolRef && node.definition() === def) {
circular = true;
}
}));
return !circular && rhs_exact_match;
}
function rhs_exact_match(node) {
return rhs.equivalent_to(node);
}
function rhs_fuzzy_match(value, fallback) {
return function(node, tw) {
if (tw.in_boolean_context()) {
if (value && node.is_truthy() && !node.has_side_effects(compressor)) {
return true;
}
if (node.is_constant()) {
return !node.evaluate(compressor) == !value;
}
}
return fallback(node);
};
}
function get_lvalues(expr) {
var lvalues = Object.create(null);
if (candidate instanceof AST.VarDef) {
lvalues[candidate.name.name] = lhs;
}
var tw = new TreeWalker(function(node) {
var sym = root_expr(node);
if (sym instanceof AST.SymbolRef || sym instanceof AST.This) {
lvalues[sym.name] = lvalues[sym.name] || is_modified(compressor, tw, node, node, 0);
}
});
expr.walk(tw);
return lvalues;
}
function remove_candidate(expr) {
if (expr.name instanceof AST.SymbolFunarg) {
var index = compressor.self().argnames.indexOf(expr.name);
var args = compressor.parent().args;
if (args[index]) args[index] = make_node(AST.Number, args[index], {
value: 0
});
return true;
}
var found = false;
return statements[stat_index].transform(new TreeTransformer(function(node, descend, in_list) {
if (found) return node;
if (node === expr || node.body === expr) {
found = true;
if (node instanceof AST.VarDef) {
node.value = null;
return node;
}
return in_list ? MAP.skip : null;
}
}, function(node) {
if (node instanceof AST.Sequence) switch (node.expressions.length) {
case 0: return null;
case 1: return node.expressions[0];
}
}));
}
function is_lhs_local(lhs) {
var sym = root_expr(lhs);
return sym instanceof AST.SymbolRef
&& sym.definition().scope === scope
&& !(in_loop
&& (sym.name in lvalues && lvalues[sym.name] !== lhs
|| candidate instanceof AST.Unary
|| candidate instanceof AST.Assign && candidate.operator != "="));
}
function value_has_side_effects(expr) {
if (expr instanceof AST.Unary) return false;
return get_rvalue(expr).has_side_effects(compressor);
}
function replace_all_symbols() {
if (side_effects) return false;
if (value_def) return true;
if (lhs instanceof AST.SymbolRef) {
var def = lhs.definition();
if (def.references.length - def.replaced == (candidate instanceof AST.VarDef ? 1 : 2)) {
return true;
}
}
return false;
}
function symbol_in_lvalues(sym, parent) {
var lvalue = lvalues[sym.name];
if (!lvalue) return;
if (lvalue !== lhs) return !(parent instanceof AST.Call);
scan_rhs = false;
}
function may_modify(sym) {
var def = sym.definition();
if (def.orig.length == 1 && def.orig[0] instanceof AST.SymbolDefun) return false;
if (def.scope !== scope) return true;
return !all(def.references, function(ref) {
var s = ref.scope;
// "block" scope within AST.Catch
if (s.TYPE == "Scope") s = s.parent_scope;
return s === scope;
});
}
function side_effects_external(node, lhs) {
if (node instanceof AST.Assign) return side_effects_external(node.left, true);
if (node instanceof AST.Unary) return side_effects_external(node.expression, true);
if (node instanceof AST.VarDef) return node.value && side_effects_external(node.value);
if (lhs) {
if (node instanceof AST.Dot) return side_effects_external(node.expression, true);
if (node instanceof AST.Sub) return side_effects_external(node.expression, true);
if (node instanceof AST.SymbolRef) return node.definition().scope !== scope;
}
return false;
}
}
function eliminate_spurious_blocks(statements) {
var seen_dirs = [];
for (var i = 0; i < statements.length;) {
var stat = statements[i];
if (stat instanceof AST.BlockStatement) {
CHANGED = true;
eliminate_spurious_blocks(stat.body);
[].splice.apply(statements, [i, 1].concat(stat.body));
i += stat.body.length;
} else if (stat instanceof AST.EmptyStatement) {
CHANGED = true;
statements.splice(i, 1);
} else if (stat instanceof AST.Directive) {
if (seen_dirs.indexOf(stat.value) < 0) {
i++;
seen_dirs.push(stat.value);
} else {
CHANGED = true;
statements.splice(i, 1);
}
} else i++;
}
}
function handle_if_return(statements, compressor) {
var self = compressor.self();
var multiple_if_returns = has_multiple_if_returns(statements);
var in_lambda = self instanceof AST.Lambda;
for (var i = statements.length; --i >= 0;) {
var stat = statements[i];
var j = next_index(i);
var next = statements[j];
if (in_lambda && !next && stat instanceof AST.Return) {
if (!stat.value) {
CHANGED = true;
statements.splice(i, 1);
continue;
}
if (stat.value instanceof AST.UnaryPrefix && stat.value.operator == "void") {
CHANGED = true;
statements[i] = make_node(AST.SimpleStatement, stat, {
body: stat.value.expression
});
continue;
}
}
if (stat instanceof AST.If) {
var ab = aborts(stat.body);
if (can_merge_flow(ab)) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
stat = stat.clone();
stat.condition = stat.condition.negate(compressor);
var body = as_statement_array_with_return(stat.body, ab);
stat.body = make_node(AST.BlockStatement, stat, {
body: as_statement_array(stat.alternative).concat(extract_functions())
});
stat.alternative = make_node(AST.BlockStatement, stat, {
body: body
});
statements[i] = stat.transform(compressor);
continue;
}
var ab = aborts(stat.alternative);
if (can_merge_flow(ab)) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
stat = stat.clone();
stat.body = make_node(AST.BlockStatement, stat.body, {
body: as_statement_array(stat.body).concat(extract_functions())
});
var body = as_statement_array_with_return(stat.alternative, ab);
stat.alternative = make_node(AST.BlockStatement, stat.alternative, {
body: body
});
statements[i] = stat.transform(compressor);
continue;
}
}
if (stat instanceof AST.If && stat.body instanceof AST.Return) {
var value = stat.body.value;
//---
// pretty silly case, but:
// if (foo()) return; return; ==> foo(); return;
if (!value && !stat.alternative
&& (in_lambda && !next || next instanceof AST.Return && !next.value)) {
CHANGED = true;
statements[i] = make_node(AST.SimpleStatement, stat.condition, {
body: stat.condition
});
continue;
}
//---
// if (foo()) return x; return y; ==> return foo() ? x : y;
if (value && !stat.alternative && next instanceof AST.Return && next.value) {
CHANGED = true;
stat = stat.clone();
stat.alternative = next;
statements.splice(i, 1, stat.transform(compressor));
statements.splice(j, 1);
continue;
}
//---
// if (foo()) return x; [ return ; ] ==> return foo() ? x : undefined;
if (value && !stat.alternative
&& (!next && in_lambda && multiple_if_returns
|| next instanceof AST.Return)) {
CHANGED = true;
stat = stat.clone();
stat.alternative = next || make_node(AST.Return, stat, {
value: null
});
statements.splice(i, 1, stat.transform(compressor));
if (next) statements.splice(j, 1);
continue;
}
//---
// if (a) return b; if (c) return d; e; ==> return a ? b : c ? d : void e;
//
// if sequences is not enabled, this can lead to an endless loop (issue #866).
// however, with sequences on this helps producing slightly better output for
// the example code.
var prev = statements[prev_index(i)];
if (compressor.option("sequences") && in_lambda && !stat.alternative
&& prev instanceof AST.If && prev.body instanceof AST.Return
&& next_index(j) == statements.length && next instanceof AST.SimpleStatement) {
CHANGED = true;
stat = stat.clone();
stat.alternative = make_node(AST.BlockStatement, next, {
body: [
next,
make_node(AST.Return, next, {
value: null
})
]
});
statements.splice(i, 1, stat.transform(compressor));
statements.splice(j, 1);
continue;
}
}
}
function has_multiple_if_returns(statements) {
var n = 0;
for (var i = statements.length; --i >= 0;) {
var stat = statements[i];
if (stat instanceof AST.If && stat.body instanceof AST.Return) {
if (++n > 1) return true;
}
}
return false;
}
function is_return_void(value) {
return !value || value instanceof AST.UnaryPrefix && value.operator == "void";
}
function can_merge_flow(ab) {
if (!ab) return false;
var lct = ab instanceof AST.LoopControl ? compressor.loopcontrol_target(ab) : null;
return ab instanceof AST.Return && in_lambda && is_return_void(ab.value)
|| ab instanceof AST.Continue && self === loop_body(lct)
|| ab instanceof AST.Break && lct instanceof AST.BlockStatement && self === lct;
}
function extract_functions() {
var tail = statements.slice(i + 1);
statements.length = i + 1;
return tail.filter(function(stat) {
if (stat instanceof AST.Defun) {
statements.push(stat);
return false;
}
return true;
});
}
function as_statement_array_with_return(node, ab) {
var body = as_statement_array(node).slice(0, -1);
if (ab.value) {
body.push(make_node(AST.SimpleStatement, ab.value, {
body: ab.value.expression
}));
}
return body;
}
function next_index(i) {
for (var j = i + 1, len = statements.length; j < len; j++) {
var stat = statements[j];
if (!(stat instanceof AST.Var && declarations_only(stat))) {
break;
}
}
return j;
}
function prev_index(i) {
for (var j = i; --j >= 0;) {
var stat = statements[j];
if (!(stat instanceof AST.Var && declarations_only(stat))) {
break;
}
}
return j;
}
}
function eliminate_dead_code(statements, compressor) {
var has_quit;
var self = compressor.self();
for (var i = 0, n = 0, len = statements.length; i < len; i++) {
var stat = statements[i];
if (stat instanceof AST.LoopControl) {
var lct = compressor.loopcontrol_target(stat);
if (stat instanceof AST.Break
&& !(lct instanceof AST.IterationStatement)
&& loop_body(lct) === self
|| stat instanceof AST.Continue
&& loop_body(lct) === self) {
if (stat.label) {
remove(stat.label.thedef.references, stat);
}
} else {
statements[n++] = stat;
}
} else {
statements[n++] = stat;
}
if (aborts(stat)) {
has_quit = statements.slice(i + 1);
break;
}
}
statements.length = n;
CHANGED = n != len;
if (has_quit) has_quit.forEach(function(stat) {
extract_declarations_from_unreachable_code(compressor, stat, statements);
});
}
function declarations_only(node) {
return all(node.definitions, function(var_def) {
return !var_def.value;
});
}
function sequencesize(statements, compressor) {
if (statements.length < 2) return;
var seq = [], n = 0;
function push_seq() {
if (!seq.length) return;
var body = make_sequence(seq[0], seq);
statements[n++] = make_node(AST.SimpleStatement, body, { body: body });
seq = [];
}
for (var i = 0, len = statements.length; i < len; i++) {
var stat = statements[i];
if (stat instanceof AST.SimpleStatement) {
if (seq.length >= compressor.sequences_limit) push_seq();
var body = stat.body;
if (seq.length > 0) body = body.drop_side_effect_free(compressor);
if (body) merge_sequence(seq, body);
} else if (stat instanceof AST.Definitions && declarations_only(stat)
|| stat instanceof AST.Defun) {
statements[n++] = stat;
} else {
push_seq();
statements[n++] = stat;
}
}
push_seq();
statements.length = n;
if (n != len) CHANGED = true;
}
function to_simple_statement(block, decls) {
if (!(block instanceof AST.BlockStatement)) return block;
var stat = null;
for (var i = 0, len = block.body.length; i < len; i++) {
var line = block.body[i];
if (line instanceof AST.Var && declarations_only(line)) {
decls.push(line);
} else if (stat) {
return false;
} else {
stat = line;
}
}
return stat;
}
function sequencesize_2(statements, compressor) {
function cons_seq(right) {
n--;
CHANGED = true;
var left = prev.body;
return make_sequence(left, [ left, right ]).transform(compressor);
}
var n = 0, prev;
for (var i = 0; i < statements.length; i++) {
var stat = statements[i];
if (prev) {
if (stat instanceof AST.Exit) {
stat.value = cons_seq(stat.value || make_node(AST.Undefined, stat).transform(compressor));
} else if (stat instanceof AST.For) {
if (!(stat.init instanceof AST.Definitions)) {
var abort = false;
prev.body.walk(new TreeWalker(function(node) {
if (abort || node instanceof AST.Scope) return true;
if (node instanceof AST.Binary && node.operator == "in") {
abort = true;
return true;
}
}));
if (!abort) {
if (stat.init) stat.init = cons_seq(stat.init);
else {
stat.init = prev.body;
n--;
CHANGED = true;
}
}
}
} else if (stat instanceof AST.ForIn) {
stat.object = cons_seq(stat.object);
} else if (stat instanceof AST.If) {
stat.condition = cons_seq(stat.condition);
} else if (stat instanceof AST.Switch) {
stat.expression = cons_seq(stat.expression);
} else if (stat instanceof AST.With) {
stat.expression = cons_seq(stat.expression);
}
}
if (compressor.option("conditionals") && stat instanceof AST.If) {
var decls = [];
var body = to_simple_statement(stat.body, decls);
var alt = to_simple_statement(stat.alternative, decls);
if (body !== false && alt !== false && decls.length > 0) {
var len = decls.length;
decls.push(make_node(AST.If, stat, {
condition: stat.condition,
body: body || make_node(AST.EmptyStatement, stat.body),
alternative: alt
}));
decls.unshift(n, 1);
[].splice.apply(statements, decls);
i += len;
n += len + 1;
prev = null;
CHANGED = true;
continue;
}
}
statements[n++] = stat;
prev = stat instanceof AST.SimpleStatement ? stat : null;
}
statements.length = n;
}
function join_object_assignments(defn, body) {
var exprs;
if (body instanceof AST.Assign) {
exprs = [ body ];
} else if (body instanceof AST.Sequence) {
exprs = body.expressions.slice();
}
if (!exprs) return;
if (defn instanceof AST.Definitions) {
var def = defn.definitions[defn.definitions.length - 1];
if (trim_object_assignments(def.name, def.value, exprs)) return exprs;
}
for (var i = exprs.length - 1; --i >= 0;) {
var expr = exprs[i];
if (!(expr instanceof AST.Assign)) continue;
if (expr.operator != "=") continue;
if (!(expr.left instanceof AST.SymbolRef)) continue;
var tail = exprs.slice(i + 1);
if (!trim_object_assignments(expr.left, expr.right, tail)) continue;
return exprs.slice(0, i + 1).concat(tail);
}
}
function trim_object_assignments(name, value, exprs) {
if (!(value instanceof AST.Object)) return;
var trimmed = false;
do {
var node = exprs[0];
if (!(node instanceof AST.Assign)) break;
if (node.operator != "=") break;
if (!(node.left instanceof AST.PropAccess)) break;
var sym = node.left.expression;
if (!(sym instanceof AST.SymbolRef)) break;
if (name.name != sym.name) break;
if (!node.right.is_constant_expression(scope)) break;
var prop = node.left.property;
if (prop instanceof AST.Node) {
prop = prop.evaluate(compressor);
}
if (prop instanceof AST.Node) break;
prop = "" + prop;
var diff = compressor.has_directive("use strict") ? function(node) {
return node.key != prop && node.key.name != prop;
} : function(node) {
return node.key.name != prop;
};
if (!all(value.properties, diff)) break;
value.properties.push(make_node(AST.ObjectKeyVal, node, {
key: prop,
value: node.right
}));
exprs.shift();
trimmed = true;
} while (exprs.length);
return trimmed;
}
function join_consecutive_vars(statements) {
var defs;
for (var i = 0, j = -1, len = statements.length; i < len; i++) {
var stat = statements[i];
var prev = statements[j];
if (stat instanceof AST.Definitions) {
if (prev && prev.TYPE == stat.TYPE) {
prev.definitions = prev.definitions.concat(stat.definitions);
CHANGED = true;
} else if (defs && defs.TYPE == stat.TYPE && declarations_only(stat)) {
defs.definitions = defs.definitions.concat(stat.definitions);
CHANGED = true;
} else {
statements[++j] = stat;
defs = stat;
}
} else if (stat instanceof AST.Exit) {
stat.value = extract_object_assignments(stat.value);
} else if (stat instanceof AST.For) {
var exprs = join_object_assignments(prev, stat.init);
if (exprs) {
CHANGED = true;
stat.init = exprs.length ? make_sequence(stat.init, exprs) : null;
statements[++j] = stat;
} else if (prev instanceof AST.Var && (!stat.init || stat.init.TYPE == prev.TYPE)) {
if (stat.init) {
prev.definitions = prev.definitions.concat(stat.init.definitions);
}
stat.init = prev;
statements[j] = stat;
CHANGED = true;
} else if (defs && stat.init && defs.TYPE == stat.init.TYPE && declarations_only(stat.init)) {
defs.definitions = defs.definitions.concat(stat.init.definitions);
stat.init = null;
statements[++j] = stat;
CHANGED = true;
} else {
statements[++j] = stat;
}
} else if (stat instanceof AST.ForIn) {
stat.object = extract_object_assignments(stat.object);
} else if (stat instanceof AST.If) {
stat.condition = extract_object_assignments(stat.condition);
} else if (stat instanceof AST.SimpleStatement) {
var exprs = join_object_assignments(prev, stat.body);
if (exprs) {
CHANGED = true;
if (!exprs.length) continue;
stat.body = make_sequence(stat.body, exprs);
}
statements[++j] = stat;
} else if (stat instanceof AST.Switch) {
stat.expression = extract_object_assignments(stat.expression);
} else if (stat instanceof AST.With) {
stat.expression = extract_object_assignments(stat.expression);
} else {
statements[++j] = stat;
}
}
statements.length = j + 1;
function extract_object_assignments(value) {
statements[++j] = stat;
var exprs = join_object_assignments(prev, value);
if (exprs) {
CHANGED = true;
if (exprs.length) {
return make_sequence(value, exprs);
} else if (value instanceof AST.Sequence) {
return value.tail_node().left;
} else {
return value.left;
}
}
return value;
}
}
}
function extract_declarations_from_unreachable_code(compressor, stat, target) {
if (!(stat instanceof AST.Defun)) {
compressor.warn("Dropping unreachable code [{file}:{line},{col}]", stat.start);
}
stat.walk(new TreeWalker(function(node) {
if (node instanceof AST.Definitions) {
compressor.warn("Declarations in unreachable code! [{file}:{line},{col}]", node.start);
node.remove_initializers();
target.push(node);
return true;
}
if (node instanceof AST.Defun) {
target.push(node);
return true;
}
if (node instanceof AST.Scope) {
return true;
}
}));
}
function get_value(key) {
if (key instanceof AST.Constant) {
return key.getValue();
}
if (key instanceof AST.UnaryPrefix
&& key.operator == "void"
&& key.expression instanceof AST.Constant) {
return;
}
return key;
}
function is_undefined(node, compressor) {
return node.is_undefined
|| node instanceof AST.Undefined
|| node instanceof AST.UnaryPrefix
&& node.operator == "void"
&& !node.expression.has_side_effects(compressor);
}
// is_truthy()
// return true if `!!node === true`
(function(def) {
def(AST.Node, return_false);
def(AST.Array, return_true);
def(AST.Assign, function() {
return this.operator == "=" && this.right.is_truthy();
});
def(AST.Lambda, return_true);
def(AST.Object, return_true);
def(AST.RegExp, return_true);
def(AST.Sequence, function() {
return this.tail_node().is_truthy();
});
def(AST.SymbolRef, function() {
var fixed = this.fixed_value();
return fixed && fixed.is_truthy();
});
})(function(node, func) {
node.DEFMETHOD("is_truthy", func);
});
// may_throw_on_access()
// returns true if this node may be null, undefined or contain `AST.Accessor`
(function(def) {
AST.Node.DEFMETHOD("may_throw_on_access", function(compressor) {
return !compressor.option("pure_getters")
|| this._dot_throw(compressor);
});
function is_strict(compressor) {
return /strict/.test(compressor.option("pure_getters"));
}
def(AST.Node, is_strict);
def(AST.Null, return_true);
def(AST.Undefined, return_true);
def(AST.Constant, return_false);
def(AST.Array, return_false);
def(AST.Object, function(compressor) {
if (!is_strict(compressor)) return false;
for (var i = this.properties.length; --i >=0;)
if (this.properties[i].value instanceof AST.Accessor) return true;
return false;
});
def(AST.Lambda, return_false);
def(AST.UnaryPostfix, return_false);
def(AST.UnaryPrefix, function() {
return this.operator == "void";
});
def(AST.Binary, function(compressor) {
return (this.operator == "&&" || this.operator == "||")
&& (this.left._dot_throw(compressor) || this.right._dot_throw(compressor));
})
def(AST.Assign, function(compressor) {
return this.operator == "="
&& this.right._dot_throw(compressor);
})
def(AST.Conditional, function(compressor) {
return this.consequent._dot_throw(compressor)
|| this.alternative._dot_throw(compressor);
})
def(AST.Dot, function(compressor) {
if (!is_strict(compressor)) return false;
var exp = this.expression;
if (exp instanceof AST.SymbolRef) exp = exp.fixed_value();
return !(exp instanceof AST.Lambda && this.property == "prototype");
});
def(AST.Sequence, function(compressor) {
return this.tail_node()._dot_throw(compressor);
});
def(AST.SymbolRef, function(compressor) {
if (this.is_undefined) return true;
if (!is_strict(compressor)) return false;
if (is_undeclared_ref(this) && this.is_declared(compressor)) return false;
if (this.is_immutable()) return false;
var fixed = this.fixed_value();
return !fixed || fixed._dot_throw(compressor);
});
})(function(node, func) {
node.DEFMETHOD("_dot_throw", func);
});
/* -----[ boolean/negation helpers ]----- */
// methods to determine whether an expression has a boolean result type
(function(def) {
var unary_bool = makePredicate("! delete");
var binary_bool = makePredicate("in instanceof == != === !== < <= >= >");
def(AST.Node, return_false);
def(AST.UnaryPrefix, function() {
return unary_bool[this.operator];
});
def(AST.Binary, function() {
return binary_bool[this.operator]
|| lazy_op[this.operator]
&& this.left.is_boolean()
&& this.right.is_boolean();
});
def(AST.Conditional, function() {
return this.consequent.is_boolean() && this.alternative.is_boolean();
});
def(AST.Assign, function() {
return this.operator == "=" && this.right.is_boolean();
});
def(AST.Sequence, function() {
return this.tail_node().is_boolean();
});
def(AST.True, return_true);
def(AST.False, return_true);
})(function(node, func) {
node.DEFMETHOD("is_boolean", func);
});
// methods to determine if an expression has a numeric result type
(function(def) {
def(AST.Node, return_false);
def(AST.Number, return_true);
var unary = makePredicate("+ - ~ ++ --");
def(AST.Unary, function() {
return unary[this.operator];
});
var binary = makePredicate("- * / % & | ^ << >> >>>");
def(AST.Binary, function(compressor) {
return binary[this.operator] || this.operator == "+"
&& this.left.is_number(compressor)
&& this.right.is_number(compressor);
});
def(AST.Assign, function(compressor) {
return binary[this.operator.slice(0, -1)]
|| this.operator == "=" && this.right.is_number(compressor);
});
def(AST.Sequence, function(compressor) {
return this.tail_node().is_number(compressor);
});
def(AST.Conditional, function(compressor) {
return this.consequent.is_number(compressor) && this.alternative.is_number(compressor);
});
})(function(node, func) {
node.DEFMETHOD("is_number", func);
});
// methods to determine if an expression has a string result type
(function(def) {
def(AST.Node, return_false);
def(AST.String, return_true);
def(AST.UnaryPrefix, function() {
return this.operator == "typeof";
});
def(AST.Binary, function(compressor) {
return this.operator == "+" &&
(this.left.is_string(compressor) || this.right.is_string(compressor));
});
def(AST.Assign, function(compressor) {
return (this.operator == "=" || this.operator == "+=") && this.right.is_string(compressor);
});
def(AST.Sequence, function(compressor) {
return this.tail_node().is_string(compressor);
});
def(AST.Conditional, function(compressor) {
return this.consequent.is_string(compressor) && this.alternative.is_string(compressor);
});
})(function(node, func) {
node.DEFMETHOD("is_string", func);
});
var lazy_op = makePredicate("&& ||");
var unary_side_effects = makePredicate("delete ++ --");
function is_lhs(node, parent) {
if (parent instanceof AST.Unary && unary_side_effects[parent.operator]) return parent.expression;
if (parent instanceof AST.Assign && parent.left === node) return node;
}
(function(def) {
AST.Node.DEFMETHOD("resolve_defines", function(compressor) {
if (!compressor.option("global_defs")) return;
var def = this._find_defs(compressor, "");
if (def) {
var node, parent = this, level = 0;
do {
node = parent;
parent = compressor.parent(level++);
} while (parent instanceof AST.PropAccess && parent.expression === node);
if (is_lhs(node, parent)) {
compressor.warn('global_defs ' + this.print_to_string() + ' redefined [{file}:{line},{col}]', this.start);
} else {
return def;
}
}
});
function to_node(value, orig) {
if (value instanceof AST.Node) return make_node(value.CTOR, orig, value);
if (Array.isArray(value)) return make_node(AST.Array, orig, {
elements: value.map(function(value) {
return to_node(value, orig);
})
});
if (value && typeof value == "object") {
var props = [];
for (var key in value) if (HOP(value, key)) {
props.push(make_node(AST.ObjectKeyVal, orig, {
key: key,
value: to_node(value[key], orig)
}));
}
return make_node(AST.Object, orig, {
properties: props
});
}
return make_node_from_constant(value, orig);
}
def(AST.Node, noop);
def(AST.Dot, function(compressor, suffix) {
return this.expression._find_defs(compressor, "." + this.property + suffix);
});
def(AST.SymbolRef, function(compressor, suffix) {
if (!this.global()) return;
var name;
var defines = compressor.option("global_defs");
if (defines && HOP(defines, (name = this.name + suffix))) {
var node = to_node(defines[name], this);
var top = compressor.find_parent(AST.Toplevel);
node.walk(new TreeWalker(function(node) {
if (node instanceof AST.SymbolRef) {
node.scope = top;
node.thedef = top.def_global(node);
}
}));
return node;
}
});
})(function(node, func) {
node.DEFMETHOD("_find_defs", func);
});
function best_of_expression(ast1, ast2) {
return ast1.print_to_string().length >
ast2.print_to_string().length
? ast2 : ast1;
}
function best_of_statement(ast1, ast2) {
return best_of_expression(make_node(AST.SimpleStatement, ast1, {
body: ast1
}), make_node(AST.SimpleStatement, ast2, {
body: ast2
})).body;
}
function best_of(compressor, ast1, ast2) {
return (first_in_statement(compressor) ? best_of_statement : best_of_expression)(ast1, ast2);
}
function convert_to_predicate(obj) {
for (var key in obj) {
obj[key] = makePredicate(obj[key]);
}
}
var object_fns = [
"constructor",
"toString",
"valueOf",
];
var native_fns = {
Array: [
"indexOf",
"join",
"lastIndexOf",
"slice",
].concat(object_fns),
Boolean: object_fns,
Function: object_fns,
Number: [
"toExponential",
"toFixed",
"toPrecision",
].concat(object_fns),
Object: object_fns,
RegExp: [
"test",
].concat(object_fns),
String: [
"charAt",
"charCodeAt",
"concat",
"indexOf",
"italics",
"lastIndexOf",
"match",
"replace",
"search",
"slice",
"split",
"substr",
"substring",
"toLowerCase",
"toUpperCase",
"trim",
].concat(object_fns),
};
convert_to_predicate(native_fns);
var static_fns = {
Array: [
"isArray",
],
Math: [
"abs",
"acos",
"asin",
"atan",
"ceil",
"cos",
"exp",
"floor",
"log",
"round",
"sin",
"sqrt",
"tan",
"atan2",
"pow",
"max",
"min",
],
Number: [
"isFinite",
"isNaN",
],
Object: [
"create",
"getOwnPropertyDescriptor",
"getOwnPropertyNames",
"getPrototypeOf",
"isExtensible",
"isFrozen",
"isSealed",
"keys",
],
String: [
"fromCharCode",
],
};
convert_to_predicate(static_fns);
// methods to evaluate a constant expression
(function(def) {
// If the node has been successfully reduced to a constant,
// then its value is returned; otherwise the element itself
// is returned.
// They can be distinguished as constant value is never a
// descendant of AST.Node.
AST.Node.DEFMETHOD("evaluate", function(compressor) {
if (!compressor.option("evaluate")) return this;
var cached = [];
var val = this._eval(compressor, cached, 1);
cached.forEach(function(node) {
delete node._eval;
});
if (!val || val instanceof RegExp) return val;
if (typeof val == "function" || typeof val == "object") return this;
return val;
});
var unaryPrefix = makePredicate("! ~ - + void");
AST.Node.DEFMETHOD("is_constant", function() {
// Accomodate when compress option evaluate=false
// as well as the common constant expressions !0 and -1
if (this instanceof AST.Constant) {
return !(this instanceof AST.RegExp);
} else {
return this instanceof AST.UnaryPrefix
&& this.expression instanceof AST.Constant
&& unaryPrefix[this.operator];
}
});
def(AST.Statement, function() {
throw new Error(string_template("Cannot evaluate a statement [{file}:{line},{col}]", this.start));
});
def(AST.Lambda, return_this);
def(AST.Node, return_this);
def(AST.Constant, function() {
return this.getValue();
});
def(AST.Function, function(compressor) {
if (compressor.option("unsafe")) {
var fn = function() {};
fn.node = this;
fn.toString = function() {
return "function(){}";
};
return fn;
}
return this;
});
def(AST.Array, function(compressor, cached, depth) {
if (compressor.option("unsafe")) {
var elements = [];
for (var i = 0, len = this.elements.length; i < len; i++) {
var element = this.elements[i];
var value = element._eval(compressor, cached, depth);
if (element === value) return this;
elements.push(value);
}
return elements;
}
return this;
});
def(AST.Object, function(compressor, cached, depth) {
if (compressor.option("unsafe")) {
var val = {};
for (var i = 0, len = this.properties.length; i < len; i++) {
var prop = this.properties[i];
var key = prop.key;
if (key instanceof AST.Symbol) {
key = key.name;
} else if (key instanceof AST.Node) {
key = key._eval(compressor, cached, depth);
if (key === prop.key) return this;
}
if (typeof Object.prototype[key] === 'function') {
return this;
}
if (prop.value instanceof AST.Function) continue;
val[key] = prop.value._eval(compressor, cached, depth);
if (val[key] === prop.value) return this;
}
return val;
}
return this;
});
var non_converting_unary = makePredicate("! typeof void");
def(AST.UnaryPrefix, function(compressor, cached, depth) {
var e = this.expression;
// Function would be evaluated to an array and so typeof would
// incorrectly return 'object'. Hence making is a special case.
if (compressor.option("typeofs")
&& this.operator == "typeof"
&& (e instanceof AST.Lambda
|| e instanceof AST.SymbolRef
&& e.fixed_value() instanceof AST.Lambda)) {
return typeof function(){};
}
if (!non_converting_unary[this.operator]) depth++;
e = e._eval(compressor, cached, depth);
if (e === this.expression) return this;
switch (this.operator) {
case "!": return !e;
case "typeof":
// typeof <RegExp> returns "object" or "function" on different platforms
// so cannot evaluate reliably
if (e instanceof RegExp) return this;
return typeof e;
case "void": return void e;
case "~": return ~e;
case "-": return -e;
case "+": return +e;
}
return this;
});
var non_converting_binary = makePredicate("&& || === !==");
def(AST.Binary, function(compressor, cached, depth) {
if (!non_converting_binary[this.operator]) depth++;
var left = this.left._eval(compressor, cached, depth);
if (left === this.left) return this;
var right = this.right._eval(compressor, cached, depth);
if (right === this.right) return this;
var result;
switch (this.operator) {
case "&&" : result = left && right; break;
case "||" : result = left || right; break;
case "|" : result = left | right; break;
case "&" : result = left & right; break;
case "^" : result = left ^ right; break;
case "+" : result = left + right; break;
case "*" : result = left * right; break;
case "/" : result = left / right; break;
case "%" : result = left % right; break;
case "-" : result = left - right; break;
case "<<" : result = left << right; break;
case ">>" : result = left >> right; break;
case ">>>" : result = left >>> right; break;
case "==" : result = left == right; break;
case "===" : result = left === right; break;
case "!=" : result = left != right; break;
case "!==" : result = left !== right; break;
case "<" : result = left < right; break;
case "<=" : result = left <= right; break;
case ">" : result = left > right; break;
case ">=" : result = left >= right; break;
default:
return this;
}
if (isNaN(result) && compressor.find_parent(AST.With)) {
// leave original expression as is
return this;
}
return result;
});
def(AST.Conditional, function(compressor, cached, depth) {
var condition = this.condition._eval(compressor, cached, depth);
if (condition === this.condition) return this;
var node = condition ? this.consequent : this.alternative;
var value = node._eval(compressor, cached, depth);
return value === node ? this : value;
});
def(AST.SymbolRef, function(compressor, cached, depth) {
var fixed = this.fixed_value();
if (!fixed) return this;
var value;
if (cached.indexOf(fixed) >= 0) {
value = fixed._eval();
} else {
this._eval = return_this;
value = fixed._eval(compressor, cached, depth);
delete this._eval;
if (value === fixed) return this;
fixed._eval = function() {
return value;
};
cached.push(fixed);
}
if (value && typeof value == "object") {
var escaped = this.definition().escaped;
if (escaped && depth > escaped) return this;
}
return value;
});
var global_objs = {
Array: Array,
Math: Math,
Number: Number,
Object: Object,
String: String,
};
var static_values = {
Math: [
"E",
"LN10",
"LN2",
"LOG2E",
"LOG10E",
"PI",
"SQRT1_2",
"SQRT2",
],
Number: [
"MAX_VALUE",
"MIN_VALUE",
"NaN",
"NEGATIVE_INFINITY",
"POSITIVE_INFINITY",
],
};
convert_to_predicate(static_values);
def(AST.PropAccess, function(compressor, cached, depth) {
if (compressor.option("unsafe")) {
var key = this.property;
if (key instanceof AST.Node) {
key = key._eval(compressor, cached, depth);
if (key === this.property) return this;
}
var exp = this.expression;
var val;
if (is_undeclared_ref(exp)) {
var static_value = static_values[exp.name];
if (!static_value || !static_value[key]) return this;
val = global_objs[exp.name];
} else {
val = exp._eval(compressor, cached, depth + 1);
if (!val || val === exp || !HOP(val, key)) return this;
if (typeof val == "function") switch (key) {
case "name":
return val.node.name ? val.node.name.name : "";
case "length":
return val.node.argnames.length;
default:
return this;
}
}
return val[key];
}
return this;
});
def(AST.Call, function(compressor, cached, depth) {
var exp = this.expression;
if (compressor.option("unsafe") && exp instanceof AST.PropAccess) {
var key = exp.property;
if (key instanceof AST.Node) {
key = key._eval(compressor, cached, depth);
if (key === exp.property) return this;
}
var val;
var e = exp.expression;
if (is_undeclared_ref(e)) {
var static_fn = static_fns[e.name];
if (!static_fn || !static_fn[key]) return this;
val = global_objs[e.name];
} else {
val = e._eval(compressor, cached, depth + 1);
if (val === e || !val) return this;
var native_fn = native_fns[val.constructor.name];
if (!native_fn || !native_fn[key]) return this;
}
var args = [];
for (var i = 0, len = this.args.length; i < len; i++) {
var arg = this.args[i];
var value = arg._eval(compressor, cached, depth);
if (arg === value) return this;
args.push(value);
}
try {
return val[key].apply(val, args);
} catch (ex) {
compressor.warn("Error evaluating {code} [{file}:{line},{col}]", {
code: this.print_to_string(),
file: this.start.file,
line: this.start.line,
col: this.start.col
});
}
}
return this;
});
def(AST.New, return_this);
})(function(node, func) {
node.DEFMETHOD("_eval", func);
});
// method to negate an expression
(function(def) {
function basic_negation(exp) {
return make_node(AST.UnaryPrefix, exp, {
operator: "!",
expression: exp
});
}
function best(orig, alt, first_in_statement) {
var negated = basic_negation(orig);
if (first_in_statement) {
var stat = make_node(AST.SimpleStatement, alt, {
body: alt
});
return best_of_expression(negated, stat) === stat ? alt : negated;
}
return best_of_expression(negated, alt);
}
def(AST.Node, function() {
return basic_negation(this);
});
def(AST.Statement, function() {
throw new Error("Cannot negate a statement");
});
def(AST.Function, function() {
return basic_negation(this);
});
def(AST.UnaryPrefix, function() {
if (this.operator == "!")
return this.expression;
return basic_negation(this);
});
def(AST.Sequence, function(compressor) {
var expressions = this.expressions.slice();
expressions.push(expressions.pop().negate(compressor));
return make_sequence(this, expressions);
});
def(AST.Conditional, function(compressor, first_in_statement) {
var self = this.clone();
self.consequent = self.consequent.negate(compressor);
self.alternative = self.alternative.negate(compressor);
return best(this, self, first_in_statement);
});
def(AST.Binary, function(compressor, first_in_statement) {
var self = this.clone(), op = this.operator;
if (compressor.option("unsafe_comps")) {
switch (op) {
case "<=" : self.operator = ">" ; return self;
case "<" : self.operator = ">=" ; return self;
case ">=" : self.operator = "<" ; return self;
case ">" : self.operator = "<=" ; return self;
}
}
switch (op) {
case "==" : self.operator = "!="; return self;
case "!=" : self.operator = "=="; return self;
case "===": self.operator = "!=="; return self;
case "!==": self.operator = "==="; return self;
case "&&":
self.operator = "||";
self.left = self.left.negate(compressor, first_in_statement);
self.right = self.right.negate(compressor);
return best(this, self, first_in_statement);
case "||":
self.operator = "&&";
self.left = self.left.negate(compressor, first_in_statement);
self.right = self.right.negate(compressor);
return best(this, self, first_in_statement);
}
return basic_negation(this);
});
})(function(node, func) {
node.DEFMETHOD("negate", function(compressor, first_in_statement) {
return func.call(this, compressor, first_in_statement);
});
});
var global_pure_fns = makePredicate("Boolean decodeURI decodeURIComponent Date encodeURI encodeURIComponent Error escape EvalError isFinite isNaN Number Object parseFloat parseInt RangeError ReferenceError String SyntaxError TypeError unescape URIError");
AST.Call.DEFMETHOD("is_expr_pure", function(compressor) {
if (compressor.option("unsafe")) {
var expr = this.expression;
if (is_undeclared_ref(expr) && global_pure_fns[expr.name]) return true;
if (expr instanceof AST.Dot && is_undeclared_ref(expr.expression)) {
var static_fn = static_fns[expr.expression.name];
return static_fn && static_fn[expr.property];
}
}
return this.pure || !compressor.pure_funcs(this);
});
AST.Node.DEFMETHOD("is_call_pure", return_false);
AST.Dot.DEFMETHOD("is_call_pure", function(compressor) {
if (!compressor.option("unsafe")) return;
var expr = this.expression;
var map;
if (expr instanceof AST.Array) {
map = native_fns.Array;
} else if (expr.is_boolean()) {
map = native_fns.Boolean;
} else if (expr.is_number(compressor)) {
map = native_fns.Number;
} else if (expr instanceof AST.RegExp) {
map = native_fns.RegExp;
} else if (expr.is_string(compressor)) {
map = native_fns.String;
} else if (!this.may_throw_on_access(compressor)) {
map = native_fns.Object;
}
return map && map[this.property];
});
// determine if expression has side effects
(function(def) {
def(AST.Node, return_true);
def(AST.EmptyStatement, return_false);
def(AST.Constant, return_false);
def(AST.This, return_false);
function any(list, compressor) {
for (var i = list.length; --i >= 0;)
if (list[i].has_side_effects(compressor))
return true;
return false;
}
def(AST.Block, function(compressor) {
return any(this.body, compressor);
});
def(AST.Call, function(compressor) {
if (!this.is_expr_pure(compressor)
&& (!this.expression.is_call_pure(compressor)
|| this.expression.has_side_effects(compressor))) {
return true;
}
return any(this.args, compressor);
});
def(AST.Switch, function(compressor) {
return this.expression.has_side_effects(compressor)
|| any(this.body, compressor);
});
def(AST.Case, function(compressor) {
return this.expression.has_side_effects(compressor)
|| any(this.body, compressor);
});
def(AST.Try, function(compressor) {
return any(this.body, compressor)
|| this.bcatch && this.bcatch.has_side_effects(compressor)
|| this.bfinally && this.bfinally.has_side_effects(compressor);
});
def(AST.If, function(compressor) {
return this.condition.has_side_effects(compressor)
|| this.body && this.body.has_side_effects(compressor)
|| this.alternative && this.alternative.has_side_effects(compressor);
});
def(AST.LabeledStatement, function(compressor) {
return this.body.has_side_effects(compressor);
});
def(AST.SimpleStatement, function(compressor) {
return this.body.has_side_effects(compressor);
});
def(AST.Lambda, return_false);
def(AST.Binary, function(compressor) {
return this.left.has_side_effects(compressor)
|| this.right.has_side_effects(compressor);
});
def(AST.Assign, return_true);
def(AST.Conditional, function(compressor) {
return this.condition.has_side_effects(compressor)
|| this.consequent.has_side_effects(compressor)
|| this.alternative.has_side_effects(compressor);
});
def(AST.Unary, function(compressor) {
return unary_side_effects[this.operator]
|| this.expression.has_side_effects(compressor);
});
def(AST.SymbolRef, function(compressor) {
return !this.is_declared(compressor);
});
def(AST.SymbolDeclaration, return_false);
def(AST.Object, function(compressor) {
return any(this.properties, compressor);
});
def(AST.ObjectProperty, function(compressor) {
return this.value.has_side_effects(compressor);
});
def(AST.Array, function(compressor) {
return any(this.elements, compressor);
});
def(AST.Dot, function(compressor) {
return this.expression.may_throw_on_access(compressor)
|| this.expression.has_side_effects(compressor);
});
def(AST.Sub, function(compressor) {
return this.expression.may_throw_on_access(compressor)
|| this.expression.has_side_effects(compressor)
|| this.property.has_side_effects(compressor);
});
def(AST.Sequence, function(compressor) {
return any(this.expressions, compressor);
});
def(AST.Definitions, function(compressor) {
return any(this.definitions, compressor);
});
def(AST.VarDef, function(compressor) {
return this.value;
});
})(function(node, func) {
node.DEFMETHOD("has_side_effects", func);
});
// determine if expression may throw
(function(def) {
def(AST.Node, return_true);
def(AST.Constant, return_false);
def(AST.EmptyStatement, return_false);
def(AST.Lambda, return_false);
def(AST.SymbolDeclaration, return_false);
def(AST.This, return_false);
function any(list, compressor) {
for (var i = list.length; --i >= 0;)
if (list[i].may_throw(compressor))
return true;
return false;
}
def(AST.Array, function(compressor) {
return any(this.elements, compressor);
});
def(AST.Assign, function(compressor) {
if (this.right.may_throw(compressor)) return true;
if (!compressor.has_directive("use strict")
&& this.operator == "="
&& this.left instanceof AST.SymbolRef) {
return false;
}
return this.left.may_throw(compressor);
});
def(AST.Binary, function(compressor) {
return this.left.may_throw(compressor)
|| this.right.may_throw(compressor);
});
def(AST.Block, function(compressor) {
return any(this.body, compressor);
});
def(AST.Call, function(compressor) {
if (any(this.args, compressor)) return true;
if (this.is_expr_pure(compressor)) return false;
if (this.expression.may_throw(compressor)) return true;
return !(this.expression instanceof AST.Lambda)
|| any(this.expression.body, compressor);
});
def(AST.Case, function(compressor) {
return this.expression.may_throw(compressor)
|| any(this.body, compressor);
});
def(AST.Conditional, function(compressor) {
return this.condition.may_throw(compressor)
|| this.consequent.may_throw(compressor)
|| this.alternative.may_throw(compressor);
});
def(AST.Definitions, function(compressor) {
return any(this.definitions, compressor);
});
def(AST.Dot, function(compressor) {
return this.expression.may_throw_on_access(compressor)
|| this.expression.may_throw(compressor);
});
def(AST.If, function(compressor) {
return this.condition.may_throw(compressor)
|| this.body && this.body.may_throw(compressor)
|| this.alternative && this.alternative.may_throw(compressor);
});
def(AST.LabeledStatement, function(compressor) {
return this.body.may_throw(compressor);
});
def(AST.Object, function(compressor) {
return any(this.properties, compressor);
});
def(AST.ObjectProperty, function(compressor) {
return this.value.may_throw(compressor);
});
def(AST.Return, function(compressor) {
return this.value && this.value.may_throw(compressor);
});
def(AST.Sequence, function(compressor) {
return any(this.expressions, compressor);
});
def(AST.SimpleStatement, function(compressor) {
return this.body.may_throw(compressor);
});
def(AST.Sub, function(compressor) {
return this.expression.may_throw_on_access(compressor)
|| this.expression.may_throw(compressor)
|| this.property.may_throw(compressor);
});
def(AST.Switch, function(compressor) {
return this.expression.may_throw(compressor)
|| any(this.body, compressor);
});
def(AST.SymbolRef, function(compressor) {
return !this.is_declared(compressor);
});
def(AST.Try, function(compressor) {
return this.bcatch ? this.bcatch.may_throw(compressor) : any(this.body, compressor)
|| this.bfinally && this.bfinally.may_throw(compressor);
});
def(AST.Unary, function(compressor) {
if (this.operator == "typeof" && this.expression instanceof AST.SymbolRef)
return false;
return this.expression.may_throw(compressor);
});
def(AST.VarDef, function(compressor) {
if (!this.value) return false;
return this.value.may_throw(compressor);
});
})(function(node, func) {
node.DEFMETHOD("may_throw", func);
});
// determine if expression is constant
(function(def) {
function all(list) {
for (var i = list.length; --i >= 0;)
if (!list[i].is_constant_expression())
return false;
return true;
}
def(AST.Node, return_false);
def(AST.Constant, return_true);
def(AST.Lambda, function(scope) {
var self = this;
var result = true;
self.walk(new TreeWalker(function(node) {
if (!result) return true;
if (node instanceof AST.SymbolRef) {
if (self.inlined) {
result = false;
return true;
}
var def = node.definition();
if (member(def, self.enclosed)
&& !self.variables.has(def.name)) {
if (scope) {
var scope_def = scope.find_variable(node);
if (def.undeclared ? !scope_def : scope_def === def) {
result = "f";
return true;
}
}
result = false;
}
return true;
}
}));
return result;
});
def(AST.Unary, function() {
return this.expression.is_constant_expression();
});
def(AST.Binary, function() {
return this.left.is_constant_expression() && this.right.is_constant_expression();
});
def(AST.Array, function() {
return all(this.elements);
});
def(AST.Object, function() {
return all(this.properties);
});
def(AST.ObjectProperty, function() {
return this.value.is_constant_expression();
});
})(function(node, func) {
node.DEFMETHOD("is_constant_expression", func);
});
// tell me if a statement aborts
function aborts(thing) {
return thing && thing.aborts();
}
(function(def) {
def(AST.Statement, return_null);
def(AST.Jump, return_this);
function block_aborts() {
var n = this.body.length;
return n > 0 && aborts(this.body[n - 1]);
}
def(AST.BlockStatement, block_aborts);
def(AST.SwitchBranch, block_aborts);
def(AST.If, function() {
return this.alternative && aborts(this.body) && aborts(this.alternative) && this;
});
})(function(node, func) {
node.DEFMETHOD("aborts", func);
});
/* -----[ optimizers ]----- */
OPT(AST.Directive, function(self, compressor) {
if (compressor.has_directive(self.value) !== self) {
return make_node(AST.EmptyStatement, self);
}
return self;
});
OPT(AST.Debugger, function(self, compressor) {
if (compressor.option("drop_debugger"))
return make_node(AST.EmptyStatement, self);
return self;
});
OPT(AST.LabeledStatement, function(self, compressor) {
if (self.body instanceof AST.Break
&& compressor.loopcontrol_target(self.body) === self.body) {
return make_node(AST.EmptyStatement, self);
}
return self.label.references.length == 0 ? self.body : self;
});
OPT(AST.Block, function(self, compressor) {
tighten_body(self.body, compressor);
return self;
});
OPT(AST.BlockStatement, function(self, compressor) {
tighten_body(self.body, compressor);
switch (self.body.length) {
case 1: return self.body[0];
case 0: return make_node(AST.EmptyStatement, self);
}
return self;
});
OPT(AST.Lambda, function(self, compressor) {
tighten_body(self.body, compressor);
if (compressor.option("side_effects")
&& self.body.length == 1
&& self.body[0] === compressor.has_directive("use strict")) {
self.body.length = 0;
}
return self;
});
AST.Scope.DEFMETHOD("drop_unused", function(compressor) {
if (!compressor.option("unused")) return;
if (compressor.has_directive("use asm")) return;
var self = this;
if (self.pinned()) return;
var drop_funcs = !(self instanceof AST.Toplevel) || compressor.toplevel.funcs;
var drop_vars = !(self instanceof AST.Toplevel) || compressor.toplevel.vars;
var assign_as_unused = /keep_assign/.test(compressor.option("unused")) ? return_false : function(node, props) {
var sym;
if (node instanceof AST.Assign && (node.write_only || node.operator == "=")) {
sym = node.left;
} else if (node instanceof AST.Unary && node.write_only) {
sym = node.expression;
}
if (/strict/.test(compressor.option("pure_getters"))) {
while (sym instanceof AST.PropAccess && !sym.expression.may_throw_on_access(compressor)) {
if (sym instanceof AST.Sub) props.unshift(sym.property);
sym = sym.expression;
}
}
return sym;
};
var in_use = [];
var in_use_ids = Object.create(null); // avoid expensive linear scans of in_use
var fixed_ids = Object.create(null);
var value_read = Object.create(null);
var value_modified = Object.create(null);
if (self instanceof AST.Toplevel && compressor.top_retain) {
self.variables.each(function(def) {
if (compressor.top_retain(def) && !(def.id in in_use_ids)) {
in_use_ids[def.id] = true;
in_use.push(def);
}
});
}
var var_defs_by_id = new Dictionary();
var initializations = new Dictionary();
// pass 1: find out which symbols are directly used in
// this scope (not in nested scopes).
var scope = this;
var tw = new TreeWalker(function(node, descend) {
if (node === self) return;
if (node instanceof AST.Defun) {
var node_def = node.name.definition();
if (!drop_funcs && scope === self) {
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
}
initializations.add(node_def.id, node);
return true; // don't go in nested scopes
}
if (node instanceof AST.SymbolFunarg && scope === self) {
var_defs_by_id.add(node.definition().id, node);
}
if (node instanceof AST.Definitions && scope === self) {
node.definitions.forEach(function(def) {
var node_def = def.name.definition();
if (def.name instanceof AST.SymbolVar) {
var_defs_by_id.add(node_def.id, def);
}
if (!drop_vars) {
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
}
if (def.value) {
initializations.add(node_def.id, def.value);
if (def.value.has_side_effects(compressor)) {
def.value.walk(tw);
}
if (!node_def.chained && def.name.fixed_value() === def.value) {
fixed_ids[node_def.id] = def;
}
}
});
return true;
}
return scan_ref_scoped(node, descend);
});
self.walk(tw);
// pass 2: for every used symbol we need to walk its
// initialization code to figure out if it uses other
// symbols (that may not be in_use).
tw = new TreeWalker(scan_ref_scoped);
for (var i = 0; i < in_use.length; i++) {
var init = initializations.get(in_use[i].id);
if (init) init.forEach(function(init) {
init.walk(tw);
});
}
// pass 3: we should drop declarations not in_use
var tt = new TreeTransformer(
function before(node, descend, in_list) {
var parent = tt.parent();
if (drop_vars) {
var props = [], sym = assign_as_unused(node, props);
if (sym instanceof AST.SymbolRef) {
var def = sym.definition();
var in_use = def.id in in_use_ids;
var value = null;
if (node instanceof AST.Assign) {
if (!in_use || node.left === sym && def.id in fixed_ids && fixed_ids[def.id] !== node) {
value = node.right;
}
} else if (!in_use) {
value = make_node(AST.Number, node, {
value: 0
});
}
if (value) {
props.push(value);
return maintain_this_binding(compressor, parent, node, make_sequence(node, props.map(function(prop) {
return prop.transform(tt);
})));
}
}
}
if (scope !== self) return;
if (node instanceof AST.Function
&& node.name
&& !compressor.option("keep_fnames")) {
var def = node.name.definition();
// any declarations with same name will overshadow
// name of this anonymous function and can therefore
// never be used anywhere
if (!(def.id in in_use_ids) || def.orig.length > 1)
node.name = null;
}
if (node instanceof AST.Lambda && !(node instanceof AST.Accessor)) {
var trim = !compressor.option("keep_fargs");
for (var a = node.argnames, i = a.length; --i >= 0;) {
var sym = a[i];
if (!(sym.definition().id in in_use_ids)) {
sym.__unused = true;
if (trim) {
a.pop();
compressor[sym.unreferenced() ? "warn" : "info"]("Dropping unused function argument {name} [{file}:{line},{col}]", template(sym));
}
}
else {
trim = false;
}
}
}
if (drop_funcs && node instanceof AST.Defun && node !== self) {
var def = node.name.definition();
if (!(def.id in in_use_ids)) {
compressor[node.name.unreferenced() ? "warn" : "info"]("Dropping unused function {name} [{file}:{line},{col}]", template(node.name));
def.eliminated++;
return make_node(AST.EmptyStatement, node);
}
}
if (node instanceof AST.Definitions && !(parent instanceof AST.ForIn && parent.init === node)) {
// place uninitialized names at the start
var body = [], head = [], tail = [];
// for unused names whose initialization has
// side effects, we can cascade the init. code
// into the next one, or next statement.
var side_effects = [];
node.definitions.forEach(function(def) {
if (def.value) def.value = def.value.transform(tt);
var sym = def.name.definition();
if (!drop_vars || sym.id in in_use_ids) {
if (def.value && sym.id in fixed_ids && fixed_ids[sym.id] !== def) {
def.value = def.value.drop_side_effect_free(compressor);
}
if (def.name instanceof AST.SymbolVar) {
var var_defs = var_defs_by_id.get(sym.id);
if (var_defs.length > 1 && (!def.value || sym.orig.indexOf(def.name) > sym.eliminated)) {
compressor.warn("Dropping duplicated definition of variable {name} [{file}:{line},{col}]", template(def.name));
if (def.value) {
var ref = make_node(AST.SymbolRef, def.name, def.name);
sym.references.push(ref);
var assign = make_node(AST.Assign, def, {
operator: "=",
left: ref,
right: def.value
});
if (fixed_ids[sym.id] === def) {
fixed_ids[sym.id] = assign;
}
side_effects.push(assign.transform(tt));
}
remove(var_defs, def);
sym.eliminated++;
return;
}
}
if (def.value) {
if (side_effects.length > 0) {
if (tail.length > 0) {
side_effects.push(def.value);
def.value = make_sequence(def.value, side_effects);
} else {
body.push(make_node(AST.SimpleStatement, node, {
body: make_sequence(node, side_effects)
}));
}
side_effects = [];
}
tail.push(def);
} else {
head.push(def);
}
} else if (sym.orig[0] instanceof AST.SymbolCatch) {
var value = def.value && def.value.drop_side_effect_free(compressor);
if (value) side_effects.push(value);
def.value = null;
head.push(def);
} else {
var value = def.value && def.value.drop_side_effect_free(compressor);
if (value) {
compressor.warn("Side effects in initialization of unused variable {name} [{file}:{line},{col}]", template(def.name));
side_effects.push(value);
} else {
compressor[def.name.unreferenced() ? "warn" : "info"]("Dropping unused variable {name} [{file}:{line},{col}]", template(def.name));
}
sym.eliminated++;
}
});
if (head.length > 0 || tail.length > 0) {
node.definitions = head.concat(tail);
body.push(node);
}
if (side_effects.length > 0) {
body.push(make_node(AST.SimpleStatement, node, {
body: make_sequence(node, side_effects)
}));
}
switch (body.length) {
case 0:
return in_list ? MAP.skip : make_node(AST.EmptyStatement, node);
case 1:
return body[0];
default:
return in_list ? MAP.splice(body) : make_node(AST.BlockStatement, node, {
body: body
});
}
}
// certain combination of unused name + side effect leads to:
// https://github.com/mishoo/UglifyJS2/issues/44
// https://github.com/mishoo/UglifyJS2/issues/1830
// https://github.com/mishoo/UglifyJS2/issues/1838
// that's an invalid AST.
// We fix it at this stage by moving the `var` outside the `for`.
if (node instanceof AST.For) {
descend(node, this);
var block;
if (node.init instanceof AST.BlockStatement) {
block = node.init;
node.init = block.body.pop();
block.body.push(node);
}
if (node.init instanceof AST.SimpleStatement) {
node.init = node.init.body;
} else if (is_empty(node.init)) {
node.init = null;
}
return !block ? node : in_list ? MAP.splice(block.body) : block;
}
if (node instanceof AST.LabeledStatement && node.body instanceof AST.For) {
descend(node, this);
if (node.body instanceof AST.BlockStatement) {
var block = node.body;
node.body = block.body.pop();
block.body.push(node);
return in_list ? MAP.splice(block.body) : block;
}
return node;
}
if (node instanceof AST.Scope) {
var save_scope = scope;
scope = node;
descend(node, this);
scope = save_scope;
return node;
}
function template(sym) {
return {
name : sym.name,
file : sym.start.file,
line : sym.start.line,
col : sym.start.col
};
}
}
);
self.transform(tt);
function verify_safe_usage(def, read, modified) {
if (def.id in in_use_ids) return;
if (read && modified) {
in_use_ids[def.id] = true;
in_use.push(def);
} else {
value_read[def.id] = read;
value_modified[def.id] = modified;
}
}
function scan_ref_scoped(node, descend) {
var node_def, props = [], sym = assign_as_unused(node, props);
if (sym instanceof AST.SymbolRef
&& self.variables.get(sym.name) === (node_def = sym.definition())) {
props.forEach(function(prop) {
prop.walk(tw);
});
if (node instanceof AST.Assign) {
node.right.walk(tw);
if (node.left === sym) {
if (!node_def.chained && sym.fixed_value() === node.right) {
fixed_ids[node_def.id] = node;
}
if (!node.write_only) {
verify_safe_usage(node_def, true, value_modified[node_def.id]);
}
} else {
var fixed = sym.fixed_value();
if (!fixed || !fixed.is_constant()) {
verify_safe_usage(node_def, value_read[node_def.id], true);
}
}
}
return true;
}
if (node instanceof AST.SymbolRef) {
node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
return true;
}
if (node instanceof AST.Scope) {
var save_scope = scope;
scope = node;
descend();
scope = save_scope;
return true;
}
}
});
AST.Scope.DEFMETHOD("hoist_declarations", function(compressor) {
if (compressor.has_directive("use asm")) return;
var hoist_funs = compressor.option("hoist_funs");
var hoist_vars = compressor.option("hoist_vars");
var self = this;
if (hoist_vars) {
// let's count var_decl first, we seem to waste a lot of
// space if we hoist `var` when there's only one.
var var_decl = 0;
self.walk(new TreeWalker(function(node) {
if (var_decl > 1) return true;
if (node instanceof AST.Scope && node !== self) return true;
if (node instanceof AST.Var) {
var_decl++;
return true;
}
}));
if (var_decl <= 1) hoist_vars = false;
}
if (!hoist_funs && !hoist_vars) return;
var dirs = [];
var hoisted = [];
var vars = new Dictionary(), vars_found = 0;
var tt = new TreeTransformer(function(node) {
if (node === self) return;
if (node instanceof AST.Directive) {
dirs.push(node);
return make_node(AST.EmptyStatement, node);
}
if (hoist_funs && node instanceof AST.Defun
&& (tt.parent() === self || !compressor.has_directive("use strict"))) {
hoisted.push(node);
return make_node(AST.EmptyStatement, node);
}
if (hoist_vars && node instanceof AST.Var) {
node.definitions.forEach(function(def) {
vars.set(def.name.name, def);
++vars_found;
});
var seq = node.to_assignments(compressor);
var p = tt.parent();
if (p instanceof AST.ForIn && p.init === node) {
if (seq) return seq;
var def = node.definitions[0].name;
return make_node(AST.SymbolRef, def, def);
}
if (p instanceof AST.For && p.init === node) return seq;
if (!seq) return make_node(AST.EmptyStatement, node);
return make_node(AST.SimpleStatement, node, {
body: seq
});
}
if (node instanceof AST.Scope) return node;
});
self.transform(tt);
if (vars_found > 0) {
// collect only vars which don't show up in self's arguments list
var defs = [];
vars.each(function(def, name) {
if (self instanceof AST.Lambda
&& !all(self.argnames, function(argname) {
return argname.name != name;
})) {
vars.del(name);
} else {
def = def.clone();
def.value = null;
defs.push(def);
vars.set(name, def);
}
});
if (defs.length > 0) {
// try to merge in assignments
for (var i = 0; i < self.body.length;) {
if (self.body[i] instanceof AST.SimpleStatement) {
var expr = self.body[i].body, sym, assign;
if (expr instanceof AST.Assign
&& expr.operator == "="
&& (sym = expr.left) instanceof AST.Symbol
&& vars.has(sym.name))
{
var def = vars.get(sym.name);
if (def.value) break;
def.value = expr.right;
remove(defs, def);
defs.push(def);
self.body.splice(i, 1);
continue;
}
if (expr instanceof AST.Sequence
&& (assign = expr.expressions[0]) instanceof AST.Assign
&& assign.operator == "="
&& (sym = assign.left) instanceof AST.Symbol
&& vars.has(sym.name))
{
var def = vars.get(sym.name);
if (def.value) break;
def.value = assign.right;
remove(defs, def);
defs.push(def);
self.body[i].body = make_sequence(expr, expr.expressions.slice(1));
continue;
}
}
if (self.body[i] instanceof AST.EmptyStatement) {
self.body.splice(i, 1);
continue;
}
if (self.body[i] instanceof AST.BlockStatement) {
var tmp = [ i, 1 ].concat(self.body[i].body);
self.body.splice.apply(self.body, tmp);
continue;
}
break;
}
defs = make_node(AST.Var, self, {
definitions: defs
});
hoisted.push(defs);
}
}
self.body = dirs.concat(hoisted, self.body);
});
AST.Scope.DEFMETHOD("var_names", function() {
var var_names = this._var_names;
if (!var_names) {
this._var_names = var_names = Object.create(null);
this.enclosed.forEach(function(def) {
var_names[def.name] = true;
});
this.variables.each(function(def, name) {
var_names[name] = true;
});
}
return var_names;
});
AST.Scope.DEFMETHOD("make_var_name", function(prefix) {
var var_names = this.var_names();
prefix = prefix.replace(/(?:^[^a-z_$]|[^a-z0-9_$])/ig, "_");
var name = prefix;
for (var i = 0; var_names[name]; i++) name = prefix + "$" + i;
var_names[name] = true;
return name;
});
AST.Scope.DEFMETHOD("hoist_properties", function(compressor) {
if (!compressor.option("hoist_props") || compressor.has_directive("use asm")) return;
var self = this;
var top_retain = self instanceof AST.Toplevel && compressor.top_retain || return_false;
var defs_by_id = Object.create(null);
self.transform(new TreeTransformer(function(node, descend) {
if (node instanceof AST.Assign
&& node.operator == "="
&& node.write_only
&& can_hoist(node.left, node.right, 1)) {
descend(node, this);
var defs = new Dictionary();
var assignments = [];
var decls = [];
node.right.properties.forEach(function(prop) {
var decl = make_sym(node.left, prop.key);
decls.push(make_node(AST.VarDef, node, {
name: decl,
value: null
}));
var sym = make_node(AST.SymbolRef, node, {
name: decl.name,
scope: self,
thedef: decl.definition()
});
sym.reference({});
assignments.push(make_node(AST.Assign, node, {
operator: "=",
left: sym,
right: prop.value
}));
});
defs_by_id[node.left.definition().id] = defs;
self.body.splice(self.body.indexOf(this.stack[1]) + 1, 0, make_node(AST.Var, node, {
definitions: decls
}));
return make_sequence(node, assignments);
}
if (node instanceof AST.VarDef && can_hoist(node.name, node.value, 0)) {
descend(node, this);
var defs = new Dictionary();
var var_defs = [];
node.value.properties.forEach(function(prop) {
var_defs.push(make_node(AST.VarDef, node, {
name: make_sym(node.name, prop.key),
value: prop.value
}));
});
defs_by_id[node.name.definition().id] = defs;
return MAP.splice(var_defs);
}
if (node instanceof AST.PropAccess && node.expression instanceof AST.SymbolRef) {
var defs = defs_by_id[node.expression.definition().id];
if (defs) {
var def = defs.get(get_value(node.property));
var sym = make_node(AST.SymbolRef, node, {
name: def.name,
scope: node.expression.scope,
thedef: def
});
sym.reference({});
return sym;
}
}
function can_hoist(sym, right, count) {
if (sym.scope !== self) return;
var def = sym.definition();
if (def.assignments != count) return;
if (def.direct_access) return;
if (def.escaped == 1) return;
if (def.references.length == count) return;
if (def.single_use) return;
if (top_retain(def)) return;
if (sym.fixed_value() !== right) return;
return right instanceof AST.Object;
}
function make_sym(sym, key) {
var new_var = make_node(AST.SymbolVar, sym, {
name: self.make_var_name(sym.name + "_" + key),
scope: self
});
var def = self.def_variable(new_var);
defs.set(key, def);
self.enclosed.push(def);
return new_var;
}
}));
});
// drop_side_effect_free()
// remove side-effect-free parts which only affects return value
(function(def) {
// Drop side-effect-free elements from an array of expressions.
// Returns an array of expressions with side-effects or null
// if all elements were dropped. Note: original array may be
// returned if nothing changed.
function trim(nodes, compressor, first_in_statement) {
var len = nodes.length;
if (!len) return null;
var ret = [], changed = false;
for (var i = 0; i < len; i++) {
var node = nodes[i].drop_side_effect_free(compressor, first_in_statement);
changed |= node !== nodes[i];
if (node) {
ret.push(node);
first_in_statement = false;
}
}
return changed ? ret.length ? ret : null : nodes;
}
def(AST.Node, return_this);
def(AST.Constant, return_null);
def(AST.This, return_null);
def(AST.Call, function(compressor, first_in_statement) {
if (!this.is_expr_pure(compressor)) {
if (this.expression.is_call_pure(compressor)) {
var exprs = this.args.slice();
exprs.unshift(this.expression.expression);
exprs = trim(exprs, compressor, first_in_statement);
return exprs && make_sequence(this, exprs);
}
if (this.expression instanceof AST.Function
&& (!this.expression.name || !this.expression.name.definition().references.length)) {
var node = this.clone();
var exp = node.expression;
exp.process_expression(false, compressor);
exp.walk(new TreeWalker(function(node) {
if (node instanceof AST.Return && node.value) {
node.value = node.value.drop_side_effect_free(compressor);
return true;
}
if (node instanceof AST.Scope && node !== exp) return true;
}));
return node;
}
return this;
}
if (this.pure) {
compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start);
}
var args = trim(this.args, compressor, first_in_statement);
return args && make_sequence(this, args);
});
def(AST.Accessor, return_null);
def(AST.Function, return_null);
def(AST.Binary, function(compressor, first_in_statement) {
var right = this.right.drop_side_effect_free(compressor);
if (!right) return this.left.drop_side_effect_free(compressor, first_in_statement);
if (lazy_op[this.operator]) {
if (right === this.right) return this;
var node = this.clone();
node.right = right;
return node;
} else {
var left = this.left.drop_side_effect_free(compressor, first_in_statement);
if (!left) return this.right.drop_side_effect_free(compressor, first_in_statement);
return make_sequence(this, [ left, right ]);
}
});
def(AST.Assign, function(compressor) {
var left = this.left;
if (left.has_side_effects(compressor)
|| compressor.has_directive("use strict")
&& left instanceof AST.PropAccess
&& left.expression.is_constant()) {
return this;
}
this.write_only = true;
if (root_expr(left).is_constant_expression(compressor.find_parent(AST.Scope))) {
return this.right.drop_side_effect_free(compressor);
}
return this;
});
def(AST.Conditional, function(compressor) {
var consequent = this.consequent.drop_side_effect_free(compressor);
var alternative = this.alternative.drop_side_effect_free(compressor);
if (consequent === this.consequent && alternative === this.alternative) return this;
if (!consequent) return alternative ? make_node(AST.Binary, this, {
operator: "||",
left: this.condition,
right: alternative
}) : this.condition.drop_side_effect_free(compressor);
if (!alternative) return make_node(AST.Binary, this, {
operator: "&&",
left: this.condition,
right: consequent
});
var node = this.clone();
node.consequent = consequent;
node.alternative = alternative;
return node;
});
def(AST.Unary, function(compressor, first_in_statement) {
if (unary_side_effects[this.operator]) {
this.write_only = !this.expression.has_side_effects(compressor);
return this;
}
if (this.operator == "typeof" && this.expression instanceof AST.SymbolRef) return null;
var expression = this.expression.drop_side_effect_free(compressor, first_in_statement);
if (first_in_statement && expression && is_iife_call(expression)) {
if (expression === this.expression && this.operator == "!") return this;
return expression.negate(compressor, first_in_statement);
}
return expression;
});
def(AST.SymbolRef, function(compressor) {
return this.is_declared(compressor) ? null : this;
});
def(AST.Object, function(compressor, first_in_statement) {
var values = trim(this.properties, compressor, first_in_statement);
return values && make_sequence(this, values);
});
def(AST.ObjectProperty, function(compressor, first_in_statement) {
return this.value.drop_side_effect_free(compressor, first_in_statement);
});
def(AST.Array, function(compressor, first_in_statement) {
var values = trim(this.elements, compressor, first_in_statement);
return values && make_sequence(this, values);
});
def(AST.Dot, function(compressor, first_in_statement) {
if (this.expression.may_throw_on_access(compressor)) return this;
return this.expression.drop_side_effect_free(compressor, first_in_statement);
});
def(AST.Sub, function(compressor, first_in_statement) {
if (this.expression.may_throw_on_access(compressor)) return this;
var expression = this.expression.drop_side_effect_free(compressor, first_in_statement);
if (!expression) return this.property.drop_side_effect_free(compressor, first_in_statement);
var property = this.property.drop_side_effect_free(compressor);
if (!property) return expression;
return make_sequence(this, [ expression, property ]);
});
def(AST.Sequence, function(compressor) {
var last = this.tail_node();
var expr = last.drop_side_effect_free(compressor);
if (expr === last) return this;
var expressions = this.expressions.slice(0, -1);
if (expr) expressions.push(expr);
return make_sequence(this, expressions);
});
})(function(node, func) {
node.DEFMETHOD("drop_side_effect_free", func);
});
OPT(AST.SimpleStatement, function(self, compressor) {
if (compressor.option("side_effects")) {
var body = self.body;
var node = body.drop_side_effect_free(compressor, true);
if (!node) {
compressor.warn("Dropping side-effect-free statement [{file}:{line},{col}]", self.start);
return make_node(AST.EmptyStatement, self);
}
if (node !== body) {
return make_node(AST.SimpleStatement, self, { body: node });
}
}
return self;
});
OPT(AST.While, function(self, compressor) {
return compressor.option("loops") ? make_node(AST.For, self, self).optimize(compressor) : self;
});
function has_break_or_continue(loop, parent) {
var found = false;
var tw = new TreeWalker(function(node) {
if (found || node instanceof AST.Scope) return true;
if (node instanceof AST.LoopControl && tw.loopcontrol_target(node) === loop) {
return found = true;
}
});
if (parent instanceof AST.LabeledStatement) tw.push(parent);
tw.push(loop);
loop.body.walk(tw);
return found;
}
OPT(AST.Do, function(self, compressor) {
if (!compressor.option("loops")) return self;
var cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
if (!(cond instanceof AST.Node)) {
if (cond) return make_node(AST.For, self, {
body: make_node(AST.BlockStatement, self.body, {
body: [
self.body,
make_node(AST.SimpleStatement, self.condition, {
body: self.condition
})
]
})
}).optimize(compressor);
if (!has_break_or_continue(self, compressor.parent())) {
return make_node(AST.BlockStatement, self.body, {
body: [
self.body,
make_node(AST.SimpleStatement, self.condition, {
body: self.condition
})
]
}).optimize(compressor);
}
}
if (self.body instanceof AST.SimpleStatement) return make_node(AST.For, self, {
condition: make_sequence(self.condition, [
self.body.body,
self.condition
]),
body: make_node(AST.EmptyStatement, self)
}).optimize(compressor);
return self;
});
function if_break_in_loop(self, compressor) {
var first = self.body instanceof AST.BlockStatement ? self.body.body[0] : self.body;
if (compressor.option("dead_code") && is_break(first)) {
var body = [];
if (self.init instanceof AST.Statement) {
body.push(self.init);
} else if (self.init) {
body.push(make_node(AST.SimpleStatement, self.init, {
body: self.init
}));
}
if (self.condition) {
body.push(make_node(AST.SimpleStatement, self.condition, {
body: self.condition
}));
}
extract_declarations_from_unreachable_code(compressor, self.body, body);
return make_node(AST.BlockStatement, self, {
body: body
});
}
if (first instanceof AST.If) {
if (is_break(first.body)) {
if (self.condition) {
self.condition = make_node(AST.Binary, self.condition, {
left: self.condition,
operator: "&&",
right: first.condition.negate(compressor),
});
} else {
self.condition = first.condition.negate(compressor);
}
drop_it(first.alternative);
} else if (is_break(first.alternative)) {
if (self.condition) {
self.condition = make_node(AST.Binary, self.condition, {
left: self.condition,
operator: "&&",
right: first.condition,
});
} else {
self.condition = first.condition;
}
drop_it(first.body);
}
}
return self;
function is_break(node) {
return node instanceof AST.Break
&& compressor.loopcontrol_target(node) === compressor.self();
}
function drop_it(rest) {
rest = as_statement_array(rest);
if (self.body instanceof AST.BlockStatement) {
self.body = self.body.clone();
self.body.body = rest.concat(self.body.body.slice(1));
self.body = self.body.transform(compressor);
} else {
self.body = make_node(AST.BlockStatement, self.body, {
body: rest
}).transform(compressor);
}
self = if_break_in_loop(self, compressor);
}
}
OPT(AST.For, function(self, compressor) {
if (!compressor.option("loops")) return self;
if (compressor.option("side_effects") && self.init) {
self.init = self.init.drop_side_effect_free(compressor);
}
if (self.condition) {
var cond = self.condition.evaluate(compressor);
if (!(cond instanceof AST.Node)) {
if (cond) self.condition = null;
else if (!compressor.option("dead_code")) {
var orig = self.condition;
self.condition = make_node_from_constant(cond, self.condition);
self.condition = best_of_expression(self.condition.transform(compressor), orig);
}
}
if (cond instanceof AST.Node) {
cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
}
if (!cond) {
if (compressor.option("dead_code")) {
var body = [];
extract_declarations_from_unreachable_code(compressor, self.body, body);
if (self.init instanceof AST.Statement) {
body.push(self.init);
} else if (self.init) {
body.push(make_node(AST.SimpleStatement, self.init, {
body: self.init
}));
}
body.push(make_node(AST.SimpleStatement, self.condition, {
body: self.condition
}));
return make_node(AST.BlockStatement, self, { body: body }).optimize(compressor);
}
} else if (self.condition && !(cond instanceof AST.Node)) {
self.body = make_node(AST.BlockStatement, self.body, {
body: [
make_node(AST.SimpleStatement, self.condition, {
body: self.condition
}),
self.body
]
});
self.condition = null;
}
}
return if_break_in_loop(self, compressor);
});
OPT(AST.If, function(self, compressor) {
if (is_empty(self.alternative)) self.alternative = null;
if (!compressor.option("conditionals")) return self;
// if condition can be statically determined, warn and drop
// one of the blocks. note, statically determined implies
// “has no side effects”; also it doesn't work for cases like
// `x && true`, though it probably should.
var cond = self.condition.evaluate(compressor);
if (!compressor.option("dead_code") && !(cond instanceof AST.Node)) {
var orig = self.condition;
self.condition = make_node_from_constant(cond, orig);
self.condition = best_of_expression(self.condition.transform(compressor), orig);
}
if (compressor.option("dead_code")) {
if (cond instanceof AST.Node) {
cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
}
if (!cond) {
compressor.warn("Condition always false [{file}:{line},{col}]", self.condition.start);
var body = [];
extract_declarations_from_unreachable_code(compressor, self.body, body);
body.push(make_node(AST.SimpleStatement, self.condition, {
body: self.condition
}));
if (self.alternative) body.push(self.alternative);
return make_node(AST.BlockStatement, self, { body: body }).optimize(compressor);
} else if (!(cond instanceof AST.Node)) {
compressor.warn("Condition always true [{file}:{line},{col}]", self.condition.start);
var body = [];
if (self.alternative) {
extract_declarations_from_unreachable_code(compressor, self.alternative, body);
}
body.push(make_node(AST.SimpleStatement, self.condition, {
body: self.condition
}));
body.push(self.body);
return make_node(AST.BlockStatement, self, { body: body }).optimize(compressor);
}
}
var negated = self.condition.negate(compressor);
var self_condition_length = self.condition.print_to_string().length;
var negated_length = negated.print_to_string().length;
var negated_is_best = negated_length < self_condition_length;
if (self.alternative && negated_is_best) {
negated_is_best = false; // because we already do the switch here.
// no need to swap values of self_condition_length and negated_length
// here because they are only used in an equality comparison later on.
self.condition = negated;
var tmp = self.body;
self.body = self.alternative || make_node(AST.EmptyStatement, self);
self.alternative = tmp;
}
if (is_empty(self.body) && is_empty(self.alternative)) {
return make_node(AST.SimpleStatement, self.condition, {
body: self.condition.clone()
}).optimize(compressor);
}
if (self.body instanceof AST.SimpleStatement
&& self.alternative instanceof AST.SimpleStatement) {
return make_node(AST.SimpleStatement, self, {
body: make_node(AST.Conditional, self, {
condition : self.condition,
consequent : self.body.body,
alternative : self.alternative.body
})
}).optimize(compressor);
}
if (is_empty(self.alternative) && self.body instanceof AST.SimpleStatement) {
if (self_condition_length === negated_length && !negated_is_best
&& self.condition instanceof AST.Binary && self.condition.operator == "||") {
// although the code length of self.condition and negated are the same,
// negated does not require additional surrounding parentheses.
// see https://github.com/mishoo/UglifyJS2/issues/979
negated_is_best = true;
}
if (negated_is_best) return make_node(AST.SimpleStatement, self, {
body: make_node(AST.Binary, self, {
operator : "||",
left : negated,
right : self.body.body
})
}).optimize(compressor);
return make_node(AST.SimpleStatement, self, {
body: make_node(AST.Binary, self, {
operator : "&&",
left : self.condition,
right : self.body.body
})
}).optimize(compressor);
}
if (self.body instanceof AST.EmptyStatement
&& self.alternative instanceof AST.SimpleStatement) {
return make_node(AST.SimpleStatement, self, {
body: make_node(AST.Binary, self, {
operator : "||",
left : self.condition,
right : self.alternative.body
})
}).optimize(compressor);
}
if (self.body instanceof AST.Exit
&& self.alternative instanceof AST.Exit
&& self.body.TYPE == self.alternative.TYPE) {
return make_node(self.body.CTOR, self, {
value: make_node(AST.Conditional, self, {
condition : self.condition,
consequent : self.body.value || make_node(AST.Undefined, self.body),
alternative : self.alternative.value || make_node(AST.Undefined, self.alternative)
}).transform(compressor)
}).optimize(compressor);
}
if (self.body instanceof AST.If
&& !self.body.alternative
&& !self.alternative) {
self = make_node(AST.If, self, {
condition: make_node(AST.Binary, self.condition, {
operator: "&&",
left: self.condition,
right: self.body.condition
}),
body: self.body.body,
alternative: null
});
}
if (aborts(self.body)) {
if (self.alternative) {
var alt = self.alternative;
self.alternative = null;
return make_node(AST.BlockStatement, self, {
body: [ self, alt ]
}).optimize(compressor);
}
}
if (aborts(self.alternative)) {
var body = self.body;
self.body = self.alternative;
self.condition = negated_is_best ? negated : self.condition.negate(compressor);
self.alternative = null;
return make_node(AST.BlockStatement, self, {
body: [ self, body ]
}).optimize(compressor);
}
return self;
});
OPT(AST.Switch, function(self, compressor) {
if (!compressor.option("switches")) return self;
var branch;
var value = self.expression.evaluate(compressor);
if (!(value instanceof AST.Node)) {
var orig = self.expression;
self.expression = make_node_from_constant(value, orig);
self.expression = best_of_expression(self.expression.transform(compressor), orig);
}
if (!compressor.option("dead_code")) return self;
if (value instanceof AST.Node) {
value = self.expression.tail_node().evaluate(compressor);
}
var decl = [];
var body = [];
var default_branch;
var exact_match;
for (var i = 0, len = self.body.length; i < len && !exact_match; i++) {
branch = self.body[i];
if (branch instanceof AST.Default) {
if (!default_branch) {
default_branch = branch;
} else {
eliminate_branch(branch, body[body.length - 1]);
}
} else if (!(value instanceof AST.Node)) {
var exp = branch.expression.evaluate(compressor);
if (!(exp instanceof AST.Node) && exp !== value) {
eliminate_branch(branch, body[body.length - 1]);
continue;
}
if (exp instanceof AST.Node) exp = branch.expression.tail_node().evaluate(compressor);
if (exp === value) {
exact_match = branch;
if (default_branch) {
var default_index = body.indexOf(default_branch);
body.splice(default_index, 1);
eliminate_branch(default_branch, body[default_index - 1]);
default_branch = null;
}
}
}
if (aborts(branch)) {
var prev = body[body.length - 1];
if (aborts(prev) && prev.body.length == branch.body.length
&& make_node(AST.BlockStatement, prev, prev).equivalent_to(make_node(AST.BlockStatement, branch, branch))) {
prev.body = [];
}
}
body.push(branch);
}
while (i < len) eliminate_branch(self.body[i++], body[body.length - 1]);
if (body.length > 0) {
body[0].body = decl.concat(body[0].body);
}
self.body = body;
while (branch = body[body.length - 1]) {
var stat = branch.body[branch.body.length - 1];
if (stat instanceof AST.Break && compressor.loopcontrol_target(stat) === self)
branch.body.pop();
if (branch.body.length || branch instanceof AST.Case
&& (default_branch || branch.expression.has_side_effects(compressor))) break;
if (body.pop() === default_branch) default_branch = null;
}
if (body.length == 0) {
return make_node(AST.BlockStatement, self, {
body: decl.concat(make_node(AST.SimpleStatement, self.expression, {
body: self.expression
}))
}).optimize(compressor);
}
if (body.length == 1 && (body[0] === exact_match || body[0] === default_branch)) {
var has_break = false;
var tw = new TreeWalker(function(node) {
if (has_break
|| node instanceof AST.Lambda
|| node instanceof AST.SimpleStatement) return true;
if (node instanceof AST.Break && tw.loopcontrol_target(node) === self)
has_break = true;
});
self.walk(tw);
if (!has_break) {
var statements = body[0].body.slice();
var exp = body[0].expression;
if (exp) statements.unshift(make_node(AST.SimpleStatement, exp, {
body: exp
}));
statements.unshift(make_node(AST.SimpleStatement, self.expression, {
body:self.expression
}));
return make_node(AST.BlockStatement, self, {
body: statements
}).optimize(compressor);
}
}
return self;
function eliminate_branch(branch, prev) {
if (prev && !aborts(prev)) {
prev.body = prev.body.concat(branch.body);
} else {
extract_declarations_from_unreachable_code(compressor, branch, decl);
}
}
});
OPT(AST.Try, function(self, compressor) {
tighten_body(self.body, compressor);
if (self.bcatch && self.bfinally && all(self.bfinally.body, is_empty)) self.bfinally = null;
if (compressor.option("dead_code") && all(self.body, is_empty)) {
var body = [];
if (self.bcatch) {
extract_declarations_from_unreachable_code(compressor, self.bcatch, body);
body.forEach(function(stat) {
if (!(stat instanceof AST.Definitions)) return;
stat.definitions.forEach(function(var_def) {
var def = var_def.name.definition().redefined();
if (!def) return;
var_def.name = var_def.name.clone();
var_def.name.thedef = def;
});
});
}
if (self.bfinally) body = body.concat(self.bfinally.body);
return make_node(AST.BlockStatement, self, {
body: body
}).optimize(compressor);
}
return self;
});
AST.Definitions.DEFMETHOD("remove_initializers", function() {
this.definitions.forEach(function(def) {
def.value = null;
});
});
AST.Definitions.DEFMETHOD("to_assignments", function(compressor) {
var reduce_vars = compressor.option("reduce_vars");
var assignments = this.definitions.reduce(function(a, def) {
if (def.value) {
var name = make_node(AST.SymbolRef, def.name, def.name);
a.push(make_node(AST.Assign, def, {
operator : "=",
left : name,
right : def.value
}));
if (reduce_vars) name.definition().fixed = false;
}
def = def.name.definition();
def.eliminated++;
def.replaced--;
return a;
}, []);
if (assignments.length == 0) return null;
return make_sequence(this, assignments);
});
OPT(AST.Definitions, function(self, compressor) {
if (self.definitions.length == 0)
return make_node(AST.EmptyStatement, self);
return self;
});
AST.Call.DEFMETHOD("lift_sequences", function(compressor) {
if (!compressor.option("sequences")) return this;
var exp = this.expression;
if (!(exp instanceof AST.Sequence)) return this;
var tail = exp.tail_node();
if (needs_unbinding(compressor, tail) && !(this instanceof AST.New)) return this;
var expressions = exp.expressions.slice(0, -1);
var node = this.clone();
node.expression = tail;
expressions.push(node);
return make_sequence(this, expressions).optimize(compressor);
});
OPT(AST.Call, function(self, compressor) {
var seq = self.lift_sequences(compressor);
if (seq !== self) {
return seq;
}
var exp = self.expression;
var fn = exp;
if (compressor.option("reduce_vars") && fn instanceof AST.SymbolRef) {
fn = fn.fixed_value();
}
var is_func = fn instanceof AST.Lambda;
if (compressor.option("unused")
&& is_func
&& !fn.uses_arguments
&& !fn.pinned()) {
var pos = 0, last = 0;
for (var i = 0, len = self.args.length; i < len; i++) {
var trim = i >= fn.argnames.length;
if (trim || fn.argnames[i].__unused) {
var node = self.args[i].drop_side_effect_free(compressor);
if (node) {
self.args[pos++] = node;
} else if (!trim) {
self.args[pos++] = make_node(AST.Number, self.args[i], {
value: 0
});
continue;
}
} else {
self.args[pos++] = self.args[i];
}
last = pos;
}
self.args.length = last;
}
if (compressor.option("unsafe")) {
if (is_undeclared_ref(exp)) switch (exp.name) {
case "Array":
if (self.args.length != 1) {
return make_node(AST.Array, self, {
elements: self.args
}).optimize(compressor);
}
break;
case "Object":
if (self.args.length == 0) {
return make_node(AST.Object, self, {
properties: []
});
}
break;
case "String":
if (self.args.length == 0) return make_node(AST.String, self, {
value: ""
});
if (self.args.length <= 1) return make_node(AST.Binary, self, {
left: self.args[0],
operator: "+",
right: make_node(AST.String, self, { value: "" })
}).optimize(compressor);
break;
case "Number":
if (self.args.length == 0) return make_node(AST.Number, self, {
value: 0
});
if (self.args.length == 1) return make_node(AST.UnaryPrefix, self, {
expression: self.args[0],
operator: "+"
}).optimize(compressor);
case "Boolean":
if (self.args.length == 0) return make_node(AST.False, self);
if (self.args.length == 1) return make_node(AST.UnaryPrefix, self, {
expression: make_node(AST.UnaryPrefix, self, {
expression: self.args[0],
operator: "!"
}),
operator: "!"
}).optimize(compressor);
break;
case "RegExp":
var params = [];
if (all(self.args, function(arg) {
var value = arg.evaluate(compressor);
params.unshift(value);
return arg !== value;
})) {
try {
return best_of(compressor, self, make_node(AST.RegExp, self, {
value: RegExp.apply(RegExp, params),
}));
} catch (ex) {
compressor.warn("Error converting {expr} [{file}:{line},{col}]", {
expr: self.print_to_string(),
file: self.start.file,
line: self.start.line,
col: self.start.col
});
}
}
break;
} else if (exp instanceof AST.Dot) switch(exp.property) {
case "toString":
if (self.args.length == 0 && !exp.expression.may_throw_on_access(compressor)) {
return make_node(AST.Binary, self, {
left: make_node(AST.String, self, { value: "" }),
operator: "+",
right: exp.expression
}).optimize(compressor);
}
break;
case "join":
if (exp.expression instanceof AST.Array) EXIT: {
var separator;
if (self.args.length > 0) {
separator = self.args[0].evaluate(compressor);
if (separator === self.args[0]) break EXIT; // not a constant
}
var elements = [];
var consts = [];
exp.expression.elements.forEach(function(el) {
var value = el.evaluate(compressor);
if (value !== el) {
consts.push(value);
} else {
if (consts.length > 0) {
elements.push(make_node(AST.String, self, {
value: consts.join(separator)
}));
consts.length = 0;
}
elements.push(el);
}
});
if (consts.length > 0) {
elements.push(make_node(AST.String, self, {
value: consts.join(separator)
}));
}
if (elements.length == 0) return make_node(AST.String, self, { value: "" });
if (elements.length == 1) {
if (elements[0].is_string(compressor)) {
return elements[0];
}
return make_node(AST.Binary, elements[0], {
operator : "+",
left : make_node(AST.String, self, { value: "" }),
right : elements[0]
});
}
if (separator == "") {
var first;
if (elements[0].is_string(compressor)
|| elements[1].is_string(compressor)) {
first = elements.shift();
} else {
first = make_node(AST.String, self, { value: "" });
}
return elements.reduce(function(prev, el) {
return make_node(AST.Binary, el, {
operator : "+",
left : prev,
right : el
});
}, first).optimize(compressor);
}
// need this awkward cloning to not affect original element
// best_of will decide which one to get through.
var node = self.clone();
node.expression = node.expression.clone();
node.expression.expression = node.expression.expression.clone();
node.expression.expression.elements = elements;
return best_of(compressor, self, node);
}
break;
case "charAt":
if (exp.expression.is_string(compressor)) {
var arg = self.args[0];
var index = arg ? arg.evaluate(compressor) : 0;
if (index !== arg) {
return make_node(AST.Sub, exp, {
expression: exp.expression,
property: make_node_from_constant(index | 0, arg || exp)
}).optimize(compressor);
}
}
break;
case "apply":
if (self.args.length == 2 && self.args[1] instanceof AST.Array) {
var args = self.args[1].elements.slice();
args.unshift(self.args[0]);
return make_node(AST.Call, self, {
expression: make_node(AST.Dot, exp, {
expression: exp.expression,
property: "call"
}),
args: args
}).optimize(compressor);
}
break;
case "call":
var func = exp.expression;
if (func instanceof AST.SymbolRef) {
func = func.fixed_value();
}
if (func instanceof AST.Lambda && !func.contains_this()) {
return (self.args.length ? make_sequence(this, [
self.args[0],
make_node(AST.Call, self, {
expression: exp.expression,
args: self.args.slice(1)
})
]) : make_node(AST.Call, self, {
expression: exp.expression,
args: []
})).optimize(compressor);
}
break;
}
}
if (compressor.option("unsafe_Function")
&& is_undeclared_ref(exp)
&& exp.name == "Function") {
// new Function() => function(){}
if (self.args.length == 0) return make_node(AST.Function, self, {
argnames: [],
body: []
});
if (all(self.args, function(x) {
return x instanceof AST.String;
})) {
// quite a corner-case, but we can handle it:
// https://github.com/mishoo/UglifyJS2/issues/203
// if the code argument is a constant, then we can minify it.
try {
var code = "n(function(" + self.args.slice(0, -1).map(function(arg) {
return arg.value;
}).join(",") + "){" + self.args[self.args.length - 1].value + "})";
var ast = parse(code);
var mangle = { ie8: compressor.option("ie8") };
ast.figure_out_scope(mangle);
var comp = new Compressor(compressor.options);
ast = ast.transform(comp);
ast.figure_out_scope(mangle);
ast.compute_char_frequency(mangle);
ast.mangle_names(mangle);
var fun;
ast.walk(new TreeWalker(function(node) {
if (fun) return true;
if (node instanceof AST.Lambda) {
fun = node;
return true;
}
}));
var code = OutputStream();
AST.BlockStatement.prototype._codegen.call(fun, fun, code);
self.args = [
make_node(AST.String, self, {
value: fun.argnames.map(function(arg) {
return arg.print_to_string();
}).join(",")
}),
make_node(AST.String, self.args[self.args.length - 1], {
value: code.get().replace(/^\{|\}$/g, "")
})
];
return self;
} catch (ex) {
if (ex instanceof JS_Parse_Error) {
compressor.warn("Error parsing code passed to new Function [{file}:{line},{col}]", self.args[self.args.length - 1].start);
compressor.warn(ex.toString());
} else {
throw ex;
}
}
}
}
var stat = is_func && fn.body[0];
var can_inline = compressor.option("inline") && !self.is_expr_pure(compressor);
if (can_inline && stat instanceof AST.Return) {
var value = stat.value;
if (!value || value.is_constant_expression()) {
if (value) {
value = value.clone(true);
} else {
value = make_node(AST.Undefined, self);
}
var args = self.args.concat(value);
return make_sequence(self, args).optimize(compressor);
}
}
if (is_func) {
var def, value, scope, in_loop, level = -1;
if (can_inline
&& !fn.uses_arguments
&& !fn.pinned()
&& !(fn.name && fn instanceof AST.Function)
&& (value = can_flatten_body(stat))
&& (exp === fn
|| compressor.option("unused")
&& (def = exp.definition()).references.length == 1
&& !recursive_ref(compressor, def)
&& fn.is_constant_expression(exp.scope))
&& !self.pure
&& !fn.contains_this()
&& can_inject_symbols()) {
fn._squeezed = true;
return make_sequence(self, flatten_fn()).optimize(compressor);
}
if (compressor.option("side_effects") && all(fn.body, is_empty)) {
var args = self.args.concat(make_node(AST.Undefined, self));
return make_sequence(self, args).optimize(compressor);
}
}
if (compressor.option("drop_console")) {
if (exp instanceof AST.PropAccess) {
var name = exp.expression;
while (name.expression) {
name = name.expression;
}
if (is_undeclared_ref(name) && name.name == "console") {
return make_node(AST.Undefined, self).optimize(compressor);
}
}
}
if (compressor.option("negate_iife")
&& compressor.parent() instanceof AST.SimpleStatement
&& is_iife_call(self)) {
return self.negate(compressor, true);
}
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);
return best_of(compressor, ev, self);
}
return self;
function return_value(stat) {
if (!stat) return make_node(AST.Undefined, self);
if (stat instanceof AST.Return) {
if (!stat.value) return make_node(AST.Undefined, self);
return stat.value.clone(true);
}
if (stat instanceof AST.SimpleStatement) {
return make_node(AST.UnaryPrefix, stat, {
operator: "void",
expression: stat.body.clone(true)
});
}
}
function can_flatten_body(stat) {
var len = fn.body.length;
if (compressor.option("inline") < 3) {
return len == 1 && return_value(stat);
}
stat = null;
for (var i = 0; i < len; i++) {
var line = fn.body[i];
if (line instanceof AST.Var) {
if (stat && !all(line.definitions, function(var_def) {
return !var_def.value;
})) {
return false;
}
} else if (line instanceof AST.EmptyStatement) {
continue;
} else if (stat) {
return false;
} else {
stat = line;
}
}
return return_value(stat);
}
function can_inject_args(catches, safe_to_inject) {
for (var i = 0, len = fn.argnames.length; i < len; i++) {
var arg = fn.argnames[i];
if (arg.__unused) continue;
if (!safe_to_inject
|| catches[arg.name]
|| identifier_atom[arg.name]
|| scope.var_names()[arg.name]) {
return false;
}
if (in_loop) in_loop.push(arg.definition());
}
return true;
}
function can_inject_vars(catches, safe_to_inject) {
var len = fn.body.length;
for (var i = 0; i < len; i++) {
var stat = fn.body[i];
if (!(stat instanceof AST.Var)) continue;
if (!safe_to_inject) return false;
for (var j = stat.definitions.length; --j >= 0;) {
var name = stat.definitions[j].name;
if (catches[name.name]
|| identifier_atom[name.name]
|| scope.var_names()[name.name]) {
return false;
}
if (in_loop) in_loop.push(name.definition());
}
}
return true;
}
function can_inject_symbols() {
var catches = Object.create(null);
do {
scope = compressor.parent(++level);
if (scope instanceof AST.Catch) {
catches[scope.argname.name] = true;
} else if (scope instanceof AST.IterationStatement) {
in_loop = [];
} else if (scope instanceof AST.SymbolRef) {
if (scope.fixed_value() instanceof AST.Scope) return false;
}
} while (!(scope instanceof AST.Scope));
var safe_to_inject = !(scope instanceof AST.Toplevel) || compressor.toplevel.vars;
var inline = compressor.option("inline");
if (!can_inject_vars(catches, inline >= 3 && safe_to_inject)) return false;
if (!can_inject_args(catches, inline >= 2 && safe_to_inject)) return false;
return !in_loop || in_loop.length == 0 || !is_reachable(fn, in_loop);
}
function append_var(decls, expressions, name, value) {
var def = name.definition();
scope.variables.set(name.name, def);
scope.enclosed.push(def);
if (!scope.var_names()[name.name]) {
scope.var_names()[name.name] = true;
decls.push(make_node(AST.VarDef, name, {
name: name,
value: null
}));
}
var sym = make_node(AST.SymbolRef, name, name);
def.references.push(sym);
if (value) expressions.push(make_node(AST.Assign, self, {
operator: "=",
left: sym,
right: value
}));
}
function flatten_args(decls, expressions) {
var len = fn.argnames.length;
for (var i = self.args.length; --i >= len;) {
expressions.push(self.args[i]);
}
for (i = len; --i >= 0;) {
var name = fn.argnames[i];
var value = self.args[i];
if (name.__unused || scope.var_names()[name.name]) {
if (value) expressions.push(value);
} else {
var symbol = make_node(AST.SymbolVar, name, name);
name.definition().orig.push(symbol);
if (!value && in_loop) value = make_node(AST.Undefined, self);
append_var(decls, expressions, symbol, value);
}
}
decls.reverse();
expressions.reverse();
}
function flatten_vars(decls, expressions) {
var pos = expressions.length;
for (var i = 0, lines = fn.body.length; i < lines; i++) {
var stat = fn.body[i];
if (!(stat instanceof AST.Var)) continue;
for (var j = 0, defs = stat.definitions.length; j < defs; j++) {
var var_def = stat.definitions[j];
var name = var_def.name;
var redef = name.definition().redefined();
if (redef) {
name = name.clone();
name.thedef = redef;
}
append_var(decls, expressions, name, var_def.value);
if (in_loop && all(fn.argnames, function(argname) {
return argname.name != name.name;
})) {
var def = fn.variables.get(name.name);
var sym = make_node(AST.SymbolRef, name, name);
def.references.push(sym);
expressions.splice(pos++, 0, make_node(AST.Assign, var_def, {
operator: "=",
left: sym,
right: make_node(AST.Undefined, name)
}));
}
}
}
}
function flatten_fn() {
var decls = [];
var expressions = [];
flatten_args(decls, expressions);
flatten_vars(decls, expressions);
expressions.push(value);
if (decls.length) {
i = scope.body.indexOf(compressor.parent(level - 1)) + 1;
scope.body.splice(i, 0, make_node(AST.Var, fn, {
definitions: decls
}));
}
return expressions;
}
});
OPT(AST.New, function(self, compressor) {
var seq = self.lift_sequences(compressor);
if (seq !== self) {
return seq;
}
if (compressor.option("unsafe")) {
var exp = self.expression;
if (is_undeclared_ref(exp)) {
switch (exp.name) {
case "Object":
case "RegExp":
case "Function":
case "Error":
case "Array":
return make_node(AST.Call, self, self).transform(compressor);
}
}
}
return self;
});
OPT(AST.Sequence, function(self, compressor) {
if (!compressor.option("side_effects")) return self;
var expressions = [];
filter_for_side_effects();
var end = expressions.length - 1;
trim_right_for_undefined();
if (end == 0) {
self = maintain_this_binding(compressor, compressor.parent(), compressor.self(), expressions[0]);
if (!(self instanceof AST.Sequence)) self = self.optimize(compressor);
return self;
}
self.expressions = expressions;
return self;
function filter_for_side_effects() {
var first = first_in_statement(compressor);
var last = self.expressions.length - 1;
self.expressions.forEach(function(expr, index) {
if (index < last) expr = expr.drop_side_effect_free(compressor, first);
if (expr) {
merge_sequence(expressions, expr);
first = false;
}
});
}
function trim_right_for_undefined() {
while (end > 0 && is_undefined(expressions[end], compressor)) end--;
if (end < expressions.length - 1) {
expressions[end] = make_node(AST.UnaryPrefix, self, {
operator : "void",
expression : expressions[end]
});
expressions.length = end + 1;
}
}
});
AST.Unary.DEFMETHOD("lift_sequences", function(compressor) {
if (compressor.option("sequences") && this.expression instanceof AST.Sequence) {
var x = this.expression.expressions.slice();
var e = this.clone();
e.expression = x.pop();
x.push(e);
return make_sequence(this, x).optimize(compressor);
}
return this;
});
OPT(AST.UnaryPostfix, function(self, compressor) {
return self.lift_sequences(compressor);
});
OPT(AST.UnaryPrefix, function(self, compressor) {
var e = self.expression;
if (self.operator == "delete"
&& !(e instanceof AST.SymbolRef
|| e instanceof AST.PropAccess
|| is_identifier_atom(e))) {
if (e instanceof AST.Sequence) {
e = e.expressions.slice();
e.push(make_node(AST.True, self));
return make_sequence(self, e).optimize(compressor);
}
return make_sequence(self, [ e, make_node(AST.True, self) ]).optimize(compressor);
}
var seq = self.lift_sequences(compressor);
if (seq !== self) {
return seq;
}
if (compressor.option("side_effects") && self.operator == "void") {
e = e.drop_side_effect_free(compressor);
if (e) {
self.expression = e;
return self;
} else {
return make_node(AST.Undefined, self).optimize(compressor);
}
}
if (compressor.option("booleans")) {
if (self.operator == "!" && e.is_truthy()) {
return make_sequence(self, [ e, make_node(AST.False, self) ]).optimize(compressor);
} else if (compressor.in_boolean_context()) switch (self.operator) {
case "!":
if (e instanceof AST.UnaryPrefix && e.operator == "!") {
// !!foo ==> foo, if we're in boolean context
return e.expression;
}
if (e instanceof AST.Binary) {
self = best_of(compressor, self, e.negate(compressor, first_in_statement(compressor)));
}
break;
case "typeof":
// typeof always returns a non-empty string, thus it's
// always true in booleans
compressor.warn("Boolean expression always true [{file}:{line},{col}]", self.start);
return (e instanceof AST.SymbolRef ? make_node(AST.True, self) : make_sequence(self, [
e,
make_node(AST.True, self)
])).optimize(compressor);
}
}
if (self.operator == "-" && e instanceof AST.Infinity) {
e = e.transform(compressor);
}
if (e instanceof AST.Binary
&& (self.operator == "+" || self.operator == "-")
&& (e.operator == "*" || e.operator == "/" || e.operator == "%")) {
return make_node(AST.Binary, self, {
operator: e.operator,
left: make_node(AST.UnaryPrefix, e.left, {
operator: self.operator,
expression: e.left
}),
right: e.right
});
}
// avoids infinite recursion of numerals
if (self.operator != "-"
|| !(e instanceof AST.Number || e instanceof AST.Infinity)) {
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);
return best_of(compressor, ev, self);
}
}
return self;
});
AST.Binary.DEFMETHOD("lift_sequences", function(compressor) {
if (compressor.option("sequences")) {
if (this.left instanceof AST.Sequence) {
var x = this.left.expressions.slice();
var e = this.clone();
e.left = x.pop();
x.push(e);
return make_sequence(this, x).optimize(compressor);
}
if (this.right instanceof AST.Sequence && !this.left.has_side_effects(compressor)) {
var assign = this.operator == "=" && this.left instanceof AST.SymbolRef;
var x = this.right.expressions;
var last = x.length - 1;
for (var i = 0; i < last; i++) {
if (!assign && x[i].has_side_effects(compressor)) break;
}
if (i == last) {
x = x.slice();
var e = this.clone();
e.right = x.pop();
x.push(e);
return make_sequence(this, x).optimize(compressor);
} else if (i > 0) {
var e = this.clone();
e.right = make_sequence(this.right, x.slice(i));
x = x.slice(0, i);
x.push(e);
return make_sequence(this, x).optimize(compressor);
}
}
}
return this;
});
var commutativeOperators = makePredicate("== === != !== * & | ^");
function is_object(node) {
return node instanceof AST.Array
|| node instanceof AST.Lambda
|| node instanceof AST.Object;
}
OPT(AST.Binary, function(self, compressor) {
function reversible() {
return self.left.is_constant()
|| self.right.is_constant()
|| !self.left.has_side_effects(compressor)
&& !self.right.has_side_effects(compressor);
}
function reverse(op) {
if (reversible()) {
if (op) self.operator = op;
var tmp = self.left;
self.left = self.right;
self.right = tmp;
}
}
if (commutativeOperators[self.operator]) {
if (self.right.is_constant()
&& !self.left.is_constant()) {
// if right is a constant, whatever side effects the
// left side might have could not influence the
// result. hence, force switch.
if (!(self.left instanceof AST.Binary
&& PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
reverse();
}
}
}
self = self.lift_sequences(compressor);
if (compressor.option("comparisons")) switch (self.operator) {
case "===":
case "!==":
var is_strict_comparison = true;
if ((self.left.is_string(compressor) && self.right.is_string(compressor)) ||
(self.left.is_number(compressor) && self.right.is_number(compressor)) ||
(self.left.is_boolean() && self.right.is_boolean()) ||
self.left.equivalent_to(self.right)) {
self.operator = self.operator.substr(0, 2);
}
// XXX: intentionally falling down to the next case
case "==":
case "!=":
// void 0 == x => null == x
if (!is_strict_comparison && is_undefined(self.left, compressor)) {
self.left = make_node(AST.Null, self.left);
}
// "undefined" == typeof x => undefined === x
else if (compressor.option("typeofs")
&& self.left instanceof AST.String
&& self.left.value == "undefined"
&& self.right instanceof AST.UnaryPrefix
&& self.right.operator == "typeof") {
var expr = self.right.expression;
if (expr instanceof AST.SymbolRef ? expr.is_declared(compressor)
: !(expr instanceof AST.PropAccess && compressor.option("ie8"))) {
self.right = expr;
self.left = make_node(AST.Undefined, self.left).optimize(compressor);
if (self.operator.length == 2) self.operator += "=";
}
}
// obj !== obj => false
else if (self.left instanceof AST.SymbolRef
&& self.right instanceof AST.SymbolRef
&& self.left.definition() === self.right.definition()
&& is_object(self.left.fixed_value())) {
return make_node(self.operator[0] == "=" ? AST.True : AST.False, self);
}
break;
case "&&":
case "||":
var lhs = self.left;
if (lhs.operator == self.operator) {
lhs = lhs.right;
}
if (lhs instanceof AST.Binary
&& lhs.operator == (self.operator == "&&" ? "!==" : "===")
&& self.right instanceof AST.Binary
&& lhs.operator == self.right.operator
&& (is_undefined(lhs.left, compressor) && self.right.left instanceof AST.Null
|| lhs.left instanceof AST.Null && is_undefined(self.right.left, compressor))
&& !lhs.right.has_side_effects(compressor)
&& lhs.right.equivalent_to(self.right.right)) {
var combined = make_node(AST.Binary, self, {
operator: lhs.operator.slice(0, -1),
left: make_node(AST.Null, self),
right: lhs.right
});
if (lhs !== self.left) {
combined = make_node(AST.Binary, self, {
operator: self.operator,
left: self.left.left,
right: combined
});
}
return combined;
}
break;
}
if (compressor.option("booleans") && self.operator == "+" && compressor.in_boolean_context()) {
var ll = self.left.evaluate(compressor);
var rr = self.right.evaluate(compressor);
if (ll && typeof ll == "string") {
compressor.warn("+ in boolean context always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.right,
make_node(AST.True, self)
]).optimize(compressor);
}
if (rr && typeof rr == "string") {
compressor.warn("+ in boolean context always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.left,
make_node(AST.True, self)
]).optimize(compressor);
}
}
if (compressor.option("comparisons") && self.is_boolean()) {
if (!(compressor.parent() instanceof AST.Binary)
|| compressor.parent() instanceof AST.Assign) {
var negated = make_node(AST.UnaryPrefix, self, {
operator: "!",
expression: self.negate(compressor, first_in_statement(compressor))
});
self = best_of(compressor, self, negated);
}
switch (self.operator) {
case ">": reverse("<"); break;
case ">=": reverse("<="); break;
}
}
if (self.operator == "+") {
if (self.right instanceof AST.String
&& self.right.getValue() == ""
&& self.left.is_string(compressor)) {
return self.left;
}
if (self.left instanceof AST.String
&& self.left.getValue() == ""
&& self.right.is_string(compressor)) {
return self.right;
}
if (self.left instanceof AST.Binary
&& self.left.operator == "+"
&& self.left.left instanceof AST.String
&& self.left.left.getValue() == ""
&& self.right.is_string(compressor)) {
self.left = self.left.right;
return self.transform(compressor);
}
}
if (compressor.option("evaluate")) {
switch (self.operator) {
case "&&":
var ll = fuzzy_eval(self.left);
if (!ll) {
compressor.warn("Condition left of && always false [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor, compressor.parent(), compressor.self(), self.left).optimize(compressor);
} else if (!(ll instanceof AST.Node)) {
compressor.warn("Condition left of && always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
}
var rr = self.right.evaluate(compressor);
if (!rr) {
if (compressor.option("booleans") && compressor.in_boolean_context()) {
compressor.warn("Boolean && always false [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.left,
make_node(AST.False, self)
]).optimize(compressor);
} else self.falsy = true;
} else if (!(rr instanceof AST.Node)) {
var parent = compressor.parent();
if (parent.operator == "&&" && parent.left === compressor.self()
|| compressor.option("booleans") && compressor.in_boolean_context()) {
compressor.warn("Dropping side-effect-free && [{file}:{line},{col}]", self.start);
return self.left.optimize(compressor);
}
}
// x || false && y ---> x ? y : false
if (self.left.operator == "||") {
var lr = self.left.right.evaluate(compressor);
if (!lr) return make_node(AST.Conditional, self, {
condition: self.left.left,
consequent: self.right,
alternative: self.left.right
}).optimize(compressor);
}
break;
case "||":
var ll = fuzzy_eval(self.left);
if (!ll) {
compressor.warn("Condition left of || always false [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
} else if (!(ll instanceof AST.Node)) {
compressor.warn("Condition left of || always true [{file}:{line},{col}]", self.start);
return maintain_this_binding(compressor, compressor.parent(), compressor.self(), self.left).optimize(compressor);
}
var rr = self.right.evaluate(compressor);
if (!rr) {
var parent = compressor.parent();
if (parent.operator == "||" && parent.left === compressor.self()
|| compressor.option("booleans") && compressor.in_boolean_context()) {
compressor.warn("Dropping side-effect-free || [{file}:{line},{col}]", self.start);
return self.left.optimize(compressor);
}
} else if (!(rr instanceof AST.Node)) {
if (compressor.option("booleans") && compressor.in_boolean_context()) {
compressor.warn("Boolean || always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [
self.left,
make_node(AST.True, self)
]).optimize(compressor);
} else self.truthy = true;
}
if (self.left.operator == "&&") {
var lr = self.left.right.evaluate(compressor);
if (lr && !(lr instanceof AST.Node)) return make_node(AST.Conditional, self, {
condition: self.left.left,
consequent: self.left.right,
alternative: self.right
}).optimize(compressor);
}
break;
}
var associative = true;
switch (self.operator) {
case "+":
// "foo" + ("bar" + x) => "foobar" + x
if (self.left instanceof AST.Constant
&& self.right instanceof AST.Binary
&& self.right.operator == "+"
&& self.right.left instanceof AST.Constant
&& self.right.is_string(compressor)) {
self = make_node(AST.Binary, self, {
operator: "+",
left: make_node(AST.String, self.left, {
value: "" + self.left.getValue() + self.right.left.getValue(),
start: self.left.start,
end: self.right.left.end
}),
right: self.right.right
});
}
// (x + "foo") + "bar" => x + "foobar"
if (self.right instanceof AST.Constant
&& self.left instanceof AST.Binary
&& self.left.operator == "+"
&& self.left.right instanceof AST.Constant
&& self.left.is_string(compressor)) {
self = make_node(AST.Binary, self, {
operator: "+",
left: self.left.left,
right: make_node(AST.String, self.right, {
value: "" + self.left.right.getValue() + self.right.getValue(),
start: self.left.right.start,
end: self.right.end
})
});
}
// (x + "foo") + ("bar" + y) => (x + "foobar") + y
if (self.left instanceof AST.Binary
&& self.left.operator == "+"
&& self.left.is_string(compressor)
&& self.left.right instanceof AST.Constant
&& self.right instanceof AST.Binary
&& self.right.operator == "+"
&& self.right.left instanceof AST.Constant
&& self.right.is_string(compressor)) {
self = make_node(AST.Binary, self, {
operator: "+",
left: make_node(AST.Binary, self.left, {
operator: "+",
left: self.left.left,
right: make_node(AST.String, self.left.right, {
value: "" + self.left.right.getValue() + self.right.left.getValue(),
start: self.left.right.start,
end: self.right.left.end
})
}),
right: self.right.right
});
}
// a + -b => a - b
if (self.right instanceof AST.UnaryPrefix
&& self.right.operator == "-"
&& self.left.is_number(compressor)) {
self = make_node(AST.Binary, self, {
operator: "-",
left: self.left,
right: self.right.expression
});
break;
}
// -a + b => b - a
if (self.left instanceof AST.UnaryPrefix
&& self.left.operator == "-"
&& reversible()
&& self.right.is_number(compressor)) {
self = make_node(AST.Binary, self, {
operator: "-",
left: self.right,
right: self.left.expression
});
break;
}
case "*":
associative = compressor.option("unsafe_math");
case "&":
case "|":
case "^":
// a + +b => +b + a
if (self.left.is_number(compressor)
&& self.right.is_number(compressor)
&& reversible()
&& !(self.left instanceof AST.Binary
&& self.left.operator != self.operator
&& PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
var reversed = make_node(AST.Binary, self, {
operator: self.operator,
left: self.right,
right: self.left
});
if (self.right instanceof AST.Constant
&& !(self.left instanceof AST.Constant)) {
self = best_of(compressor, reversed, self);
} else {
self = best_of(compressor, self, reversed);
}
}
if (associative && self.is_number(compressor)) {
// a + (b + c) => (a + b) + c
if (self.right instanceof AST.Binary
&& self.right.operator == self.operator) {
self = make_node(AST.Binary, self, {
operator: self.operator,
left: make_node(AST.Binary, self.left, {
operator: self.operator,
left: self.left,
right: self.right.left,
start: self.left.start,
end: self.right.left.end
}),
right: self.right.right
});
}
// (n + 2) + 3 => 5 + n
// (2 * n) * 3 => 6 + n
if (self.right instanceof AST.Constant
&& self.left instanceof AST.Binary
&& self.left.operator == self.operator) {
if (self.left.left instanceof AST.Constant) {
self = make_node(AST.Binary, self, {
operator: self.operator,
left: make_node(AST.Binary, self.left, {
operator: self.operator,
left: self.left.left,
right: self.right,
start: self.left.left.start,
end: self.right.end
}),
right: self.left.right
});
} else if (self.left.right instanceof AST.Constant) {
self = make_node(AST.Binary, self, {
operator: self.operator,
left: make_node(AST.Binary, self.left, {
operator: self.operator,
left: self.left.right,
right: self.right,
start: self.left.right.start,
end: self.right.end
}),
right: self.left.left
});
}
}
// (a | 1) | (2 | d) => (3 | a) | b
if (self.left instanceof AST.Binary
&& self.left.operator == self.operator
&& self.left.right instanceof AST.Constant
&& self.right instanceof AST.Binary
&& self.right.operator == self.operator
&& self.right.left instanceof AST.Constant) {
self = make_node(AST.Binary, self, {
operator: self.operator,
left: make_node(AST.Binary, self.left, {
operator: self.operator,
left: make_node(AST.Binary, self.left.left, {
operator: self.operator,
left: self.left.right,
right: self.right.left,
start: self.left.right.start,
end: self.right.left.end
}),
right: self.left.left
}),
right: self.right.right
});
}
}
}
}
// x && (y && z) ==> x && y && z
// x || (y || z) ==> x || y || z
// x + ("y" + z) ==> x + "y" + z
// "x" + (y + "z")==> "x" + y + "z"
if (self.right instanceof AST.Binary
&& self.right.operator == self.operator
&& (lazy_op[self.operator]
|| (self.operator == "+"
&& (self.right.left.is_string(compressor)
|| (self.left.is_string(compressor)
&& self.right.right.is_string(compressor))))))
{
self.left = make_node(AST.Binary, self.left, {
operator : self.operator,
left : self.left,
right : self.right.left
});
self.right = self.right.right;
return self.transform(compressor);
}
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);
return best_of(compressor, ev, self);
}
return self;
function fuzzy_eval(node) {
if (node.truthy) return true;
if (node.falsy) return false;
if (node.is_truthy()) return true;
return node.evaluate(compressor);
}
});
function recursive_ref(compressor, def) {
var node;
for (var i = 0; node = compressor.parent(i); i++) {
if (node instanceof AST.Lambda) {
var name = node.name;
if (name && name.definition() === def) break;
}
}
return node;
}
OPT(AST.SymbolRef, function(self, compressor) {
var def = self.resolve_defines(compressor);
if (def) {
return def.optimize(compressor);
}
// testing against !self.scope.uses_with first is an optimization
if (!compressor.option("ie8")
&& is_undeclared_ref(self)
&& (!self.scope.uses_with || !compressor.find_parent(AST.With))) {
switch (self.name) {
case "undefined":
return make_node(AST.Undefined, self).optimize(compressor);
case "NaN":
return make_node(AST.NaN, self).optimize(compressor);
case "Infinity":
return make_node(AST.Infinity, self).optimize(compressor);
}
}
var parent = compressor.parent();
if (compressor.option("reduce_vars") && is_lhs(self, parent) !== self) {
var d = self.definition();
var fixed = self.fixed_value();
var single_use = d.single_use
&& !(parent instanceof AST.Call && parent.is_expr_pure(compressor));
if (single_use && fixed instanceof AST.Lambda) {
if (d.scope !== self.scope
&& (!compressor.option("reduce_funcs")
|| d.escaped == 1
|| fixed.inlined)) {
single_use = false;
} else if (recursive_ref(compressor, d)) {
single_use = false;
} else if (d.scope !== self.scope || d.orig[0] instanceof AST.SymbolFunarg) {
single_use = fixed.is_constant_expression(self.scope);
if (single_use == "f") {
var scope = self.scope;
do {
if (scope instanceof AST.Defun || scope instanceof AST.Function) {
scope.inlined = true;
}
} while (scope = scope.parent_scope);
}
}
}
if (single_use && fixed) {
if (fixed instanceof AST.Defun) {
fixed._squeezed = true;
fixed = make_node(AST.Function, fixed, fixed);
}
var value;
if (d.recursive_refs > 0 && fixed.name instanceof AST.SymbolDefun) {
value = fixed.clone(true);
var defun_def = value.name.definition();
var lambda_def = value.variables.get(value.name.name);
var name = lambda_def && lambda_def.orig[0];
if (!(name instanceof AST.SymbolLambda)) {
name = make_node(AST.SymbolLambda, value.name, value.name);
name.scope = value;
value.name = name;
lambda_def = value.def_function(name);
}
value.walk(new TreeWalker(function(node) {
if (node instanceof AST.SymbolRef && node.definition() === defun_def) {
node.thedef = lambda_def;
lambda_def.references.push(node);
}
}));
} else {
value = fixed.optimize(compressor);
if (value === fixed) value = fixed.clone(true);
}
return value;
}
if (fixed && d.should_replace === undefined) {
var init;
if (fixed instanceof AST.This) {
if (!(d.orig[0] instanceof AST.SymbolFunarg)
&& all(d.references, function(ref) {
return d.scope === ref.scope;
})) {
init = fixed;
}
} else {
var ev = fixed.evaluate(compressor);
if (ev !== fixed && (compressor.option("unsafe_regexp") || !(ev instanceof RegExp))) {
init = make_node_from_constant(ev, fixed);
}
}
if (init) {
var value_length = init.optimize(compressor).print_to_string().length;
var fn;
if (has_symbol_ref(fixed)) {
fn = function() {
var result = init.optimize(compressor);
return result === init ? result.clone(true) : result;
};
} else {
value_length = Math.min(value_length, fixed.print_to_string().length);
fn = function() {
var result = best_of_expression(init.optimize(compressor), fixed);
return result === init || result === fixed ? result.clone(true) : result;
};
}
var name_length = d.name.length;
var overhead = 0;
if (compressor.option("unused") && !compressor.exposed(d)) {
overhead = (name_length + 2 + value_length) / (d.references.length - d.assignments);
}
d.should_replace = value_length <= name_length + overhead ? fn : false;
} else {
d.should_replace = false;
}
}
if (d.should_replace) {
return d.should_replace();
}
}
return self;
function has_symbol_ref(value) {
var found;
value.walk(new TreeWalker(function(node) {
if (node instanceof AST.SymbolRef) found = true;
if (found) return true;
}));
return found;
}
});
function is_atomic(lhs, self) {
return lhs instanceof AST.SymbolRef || lhs.TYPE === self.TYPE;
}
OPT(AST.Undefined, function(self, compressor) {
if (compressor.option("unsafe_undefined")) {
var undef = find_variable(compressor, "undefined");
if (undef) {
var ref = make_node(AST.SymbolRef, self, {
name : "undefined",
scope : undef.scope,
thedef : undef
});
ref.is_undefined = true;
return ref;
}
}
var lhs = is_lhs(compressor.self(), compressor.parent());
if (lhs && is_atomic(lhs, self)) return self;
return make_node(AST.UnaryPrefix, self, {
operator: "void",
expression: make_node(AST.Number, self, {
value: 0
})
});
});
OPT(AST.Infinity, function(self, compressor) {
var lhs = is_lhs(compressor.self(), compressor.parent());
if (lhs && is_atomic(lhs, self)) return self;
if (compressor.option("keep_infinity")
&& !(lhs && !is_atomic(lhs, self))
&& !find_variable(compressor, "Infinity"))
return self;
return make_node(AST.Binary, self, {
operator: "/",
left: make_node(AST.Number, self, {
value: 1
}),
right: make_node(AST.Number, self, {
value: 0
})
});
});
OPT(AST.NaN, function(self, compressor) {
var lhs = is_lhs(compressor.self(), compressor.parent());
if (lhs && !is_atomic(lhs, self)
|| find_variable(compressor, "NaN")) {
return make_node(AST.Binary, self, {
operator: "/",
left: make_node(AST.Number, self, {
value: 0
}),
right: make_node(AST.Number, self, {
value: 0
})
});
}
return self;
});
function is_reachable(self, defs) {
var reachable = false;
var find_ref = new TreeWalker(function(node) {
if (reachable) return true;
if (node instanceof AST.SymbolRef && member(node.definition(), defs)) {
return reachable = true;
}
});
var scan_scope = new TreeWalker(function(node) {
if (reachable) return true;
if (node instanceof AST.Scope && node !== self) {
var parent = scan_scope.parent();
if (parent instanceof AST.Call && parent.expression === node) return;
node.walk(find_ref);
return true;
}
});
self.walk(scan_scope);
return reachable;
}
var ASSIGN_OPS = makePredicate("+ - / * % >> << >>> | ^ &");
var ASSIGN_OPS_COMMUTATIVE = makePredicate("* | ^ &");
OPT(AST.Assign, function(self, compressor) {
var def;
if (compressor.option("dead_code")
&& self.left instanceof AST.SymbolRef
&& (def = self.left.definition()).scope === compressor.find_parent(AST.Lambda)) {
var level = 0, node, parent = self;
do {
node = parent;
parent = compressor.parent(level++);
if (parent instanceof AST.Exit) {
if (in_try(level, parent)) break;
if (is_reachable(def.scope, [ def ])) break;
if (self.operator == "=") return self.right;
def.fixed = false;
return make_node(AST.Binary, self, {
operator: self.operator.slice(0, -1),
left: self.left,
right: self.right
}).optimize(compressor);
}
} while (parent instanceof AST.Binary && parent.right === node
|| parent instanceof AST.Sequence && parent.tail_node() === node);
}
self = self.lift_sequences(compressor);
if (self.operator == "=" && self.left instanceof AST.SymbolRef && self.right instanceof AST.Binary) {
// x = expr1 OP expr2
if (self.right.left instanceof AST.SymbolRef
&& self.right.left.name == self.left.name
&& ASSIGN_OPS[self.right.operator]) {
// x = x - 2 ---> x -= 2
self.operator = self.right.operator + "=";
self.right = self.right.right;
}
else if (self.right.right instanceof AST.SymbolRef
&& self.right.right.name == self.left.name
&& ASSIGN_OPS_COMMUTATIVE[self.right.operator]
&& !self.right.left.has_side_effects(compressor)) {
// x = 2 & x ---> x &= 2
self.operator = self.right.operator + "=";
self.right = self.right.left;
}
}
return self;
function in_try(level, node) {
var right = self.right;
self.right = make_node(AST.Null, right);
var may_throw = node.may_throw(compressor);
self.right = right;
var scope = self.left.definition().scope;
var parent;
while ((parent = compressor.parent(level++)) !== scope) {
if (parent instanceof AST.Try) {
if (parent.bfinally) return true;
if (may_throw && parent.bcatch) return true;
}
}
}
});
OPT(AST.Conditional, function(self, compressor) {
if (!compressor.option("conditionals")) return self;
// This looks like lift_sequences(), should probably be under "sequences"
if (self.condition instanceof AST.Sequence) {
var expressions = self.condition.expressions.slice();
self.condition = expressions.pop();
expressions.push(self);
return make_sequence(self, expressions);
}
var cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
if (!cond) {
compressor.warn("Condition always false [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.condition, self.alternative ]).optimize(compressor);
} else if (!(cond instanceof AST.Node)) {
compressor.warn("Condition always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [ self.condition, self.consequent ]).optimize(compressor);
}
var negated = cond.negate(compressor, first_in_statement(compressor));
if (best_of(compressor, cond, negated) === negated) {
self = make_node(AST.Conditional, self, {
condition: negated,
consequent: self.alternative,
alternative: self.consequent
});
}
var condition = self.condition;
var consequent = self.consequent;
var alternative = self.alternative;
// x?x:y --> x||y
if (condition instanceof AST.SymbolRef
&& consequent instanceof AST.SymbolRef
&& condition.definition() === consequent.definition()) {
return make_node(AST.Binary, self, {
operator: "||",
left: condition,
right: alternative
});
}
// if (foo) exp = something; else exp = something_else;
// |
// v
// exp = foo ? something : something_else;
if (consequent instanceof AST.Assign
&& alternative instanceof AST.Assign
&& consequent.operator == alternative.operator
&& consequent.left.equivalent_to(alternative.left)
&& (!self.condition.has_side_effects(compressor)
|| consequent.operator == "="
&& !consequent.left.has_side_effects(compressor))) {
return make_node(AST.Assign, self, {
operator: consequent.operator,
left: consequent.left,
right: make_node(AST.Conditional, self, {
condition: self.condition,
consequent: consequent.right,
alternative: alternative.right
})
});
}
// x ? y(a) : y(b) --> y(x ? a : b)
var arg_index;
if (consequent instanceof AST.Call
&& alternative.TYPE === consequent.TYPE
&& consequent.args.length > 0
&& consequent.args.length == alternative.args.length
&& consequent.expression.equivalent_to(alternative.expression)
&& !self.condition.has_side_effects(compressor)
&& !consequent.expression.has_side_effects(compressor)
&& typeof (arg_index = single_arg_diff()) == "number") {
var node = consequent.clone();
node.args[arg_index] = make_node(AST.Conditional, self, {
condition: self.condition,
consequent: consequent.args[arg_index],
alternative: alternative.args[arg_index]
});
return node;
}
// x?y?z:a:a --> x&&y?z:a
if (consequent instanceof AST.Conditional
&& consequent.alternative.equivalent_to(alternative)) {
return make_node(AST.Conditional, self, {
condition: make_node(AST.Binary, self, {
left: self.condition,
operator: "&&",
right: consequent.condition
}),
consequent: consequent.consequent,
alternative: alternative
});
}
// x ? y : y --> x, y
if (consequent.equivalent_to(alternative)) {
return make_sequence(self, [
self.condition,
consequent
]).optimize(compressor);
}
// x ? (y, w) : (z, w) --> x ? y : z, w
if ((consequent instanceof AST.Sequence || alternative instanceof AST.Sequence)
&& consequent.tail_node().equivalent_to(alternative.tail_node())) {
return make_sequence(self, [
make_node(AST.Conditional, self, {
condition: self.condition,
consequent: pop_seq(consequent),
alternative: pop_seq(alternative)
}),
consequent.tail_node()
]).optimize(compressor);
}
// x ? y || z : z --> x && y || z
if (consequent instanceof AST.Binary
&& consequent.operator == "||"
&& consequent.right.equivalent_to(alternative)) {
return make_node(AST.Binary, self, {
operator: "||",
left: make_node(AST.Binary, self, {
operator: "&&",
left: self.condition,
right: consequent.left
}),
right: alternative
}).optimize(compressor);
}
var in_bool = compressor.option("booleans") && compressor.in_boolean_context();
if (is_true(self.consequent)) {
if (is_false(self.alternative)) {
// c ? true : false ---> !!c
return booleanize(self.condition);
}
// c ? true : x ---> !!c || x
return make_node(AST.Binary, self, {
operator: "||",
left: booleanize(self.condition),
right: self.alternative
});
}
if (is_false(self.consequent)) {
if (is_true(self.alternative)) {
// c ? false : true ---> !c
return booleanize(self.condition.negate(compressor));
}
// c ? false : x ---> !c && x
return make_node(AST.Binary, self, {
operator: "&&",
left: booleanize(self.condition.negate(compressor)),
right: self.alternative
});
}
if (is_true(self.alternative)) {
// c ? x : true ---> !c || x
return make_node(AST.Binary, self, {
operator: "||",
left: booleanize(self.condition.negate(compressor)),
right: self.consequent
});
}
if (is_false(self.alternative)) {
// c ? x : false ---> !!c && x
return make_node(AST.Binary, self, {
operator: "&&",
left: booleanize(self.condition),
right: self.consequent
});
}
return self;
function booleanize(node) {
if (node.is_boolean()) return node;
// !!expression
return make_node(AST.UnaryPrefix, node, {
operator: "!",
expression: node.negate(compressor)
});
}
// AST.True or !0
function is_true(node) {
return node instanceof AST.True
|| in_bool
&& node instanceof AST.Constant
&& node.getValue()
|| (node instanceof AST.UnaryPrefix
&& node.operator == "!"
&& node.expression instanceof AST.Constant
&& !node.expression.getValue());
}
// AST.False or !1
function is_false(node) {
return node instanceof AST.False
|| in_bool
&& node instanceof AST.Constant
&& !node.getValue()
|| (node instanceof AST.UnaryPrefix
&& node.operator == "!"
&& node.expression instanceof AST.Constant
&& node.expression.getValue());
}
function single_arg_diff() {
var a = consequent.args;
var b = alternative.args;
for (var i = 0, len = a.length; i < len; i++) {
if (!a[i].equivalent_to(b[i])) {
for (var j = i + 1; j < len; j++) {
if (!a[j].equivalent_to(b[j])) return;
}
return i;
}
}
}
function pop_seq(node) {
if (!(node instanceof AST.Sequence)) return make_node(AST.Number, node, {
value: 0
});
return make_sequence(node, node.expressions.slice(0, -1));
}
});
OPT(AST.Boolean, function(self, compressor) {
if (!compressor.option("booleans")) return self;
if (compressor.in_boolean_context()) return make_node(AST.Number, self, {
value: +self.value
});
var p = compressor.parent();
if (p instanceof AST.Binary && (p.operator == "==" || p.operator == "!=")) {
compressor.warn("Non-strict equality against boolean: {operator} {value} [{file}:{line},{col}]", {
operator : p.operator,
value : self.value,
file : p.start.file,
line : p.start.line,
col : p.start.col,
});
return make_node(AST.Number, self, {
value: +self.value
});
}
return make_node(AST.UnaryPrefix, self, {
operator: "!",
expression: make_node(AST.Number, self, {
value: 1 - self.value
})
});
});
OPT(AST.Sub, function(self, compressor) {
var expr = self.expression;
var prop = self.property;
if (compressor.option("properties")) {
var key = prop.evaluate(compressor);
if (key !== prop) {
if (typeof key == "string") {
if (key == "undefined") {
key = undefined;
} else {
var value = parseFloat(key);
if (value.toString() == key) {
key = value;
}
}
}
prop = self.property = best_of_expression(prop, make_node_from_constant(key, prop).transform(compressor));
var property = "" + key;
if (is_identifier_string(property)
&& property.length <= prop.print_to_string().length + 1) {
return make_node(AST.Dot, self, {
expression: expr,
property: property
}).optimize(compressor);
}
}
}
if (is_lhs(self, compressor.parent())) return self;
if (key !== prop) {
var sub = self.flatten_object(property, compressor);
if (sub) {
expr = self.expression = sub.expression;
prop = self.property = sub.property;
}
}
if (compressor.option("properties") && compressor.option("side_effects")
&& prop instanceof AST.Number && expr instanceof AST.Array) {
var index = prop.getValue();
var elements = expr.elements;
if (index in elements) {
var flatten = true;
var values = [];
for (var i = elements.length; --i > index;) {
var value = elements[i].drop_side_effect_free(compressor);
if (value) {
values.unshift(value);
if (flatten && value.has_side_effects(compressor)) flatten = false;
}
}
var retValue = elements[index];
retValue = retValue instanceof AST.Hole ? make_node(AST.Undefined, retValue) : retValue;
if (!flatten) values.unshift(retValue);
while (--i >= 0) {
var value = elements[i].drop_side_effect_free(compressor);
if (value) values.unshift(value);
else index--;
}
if (flatten) {
values.push(retValue);
return make_sequence(self, values).optimize(compressor);
} else return make_node(AST.Sub, self, {
expression: make_node(AST.Array, expr, {
elements: values
}),
property: make_node(AST.Number, prop, {
value: index
})
});
}
}
var fn;
if (compressor.option("arguments")
&& expr instanceof AST.SymbolRef
&& expr.name == "arguments"
&& expr.definition().orig.length == 1
&& (fn = expr.scope) instanceof AST.Lambda
&& prop instanceof AST.Number) {
var index = prop.getValue();
var argname = fn.argnames[index];
if (!argname && !compressor.option("keep_fargs")) {
while (index >= fn.argnames.length) {
argname = make_node(AST.SymbolFunarg, fn, {
name: fn.make_var_name("argument_" + fn.argnames.length),
scope: fn
});
fn.argnames.push(argname);
fn.enclosed.push(fn.def_variable(argname));
}
}
if (argname) {
var sym = make_node(AST.SymbolRef, self, argname);
sym.reference({});
return sym;
}
}
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);
return best_of(compressor, ev, self);
}
return self;
});
AST.Scope.DEFMETHOD("contains_this", function() {
var result;
var self = this;
self.walk(new TreeWalker(function(node) {
if (result) return true;
if (node instanceof AST.This) return result = true;
if (node !== self && node instanceof AST.Scope) return true;
}));
return result;
});
AST.PropAccess.DEFMETHOD("flatten_object", function(key, compressor) {
if (!compressor.option("properties")) return;
var expr = this.expression;
if (expr instanceof AST.Object) {
var props = expr.properties;
for (var i = props.length; --i >= 0;) {
var prop = props[i];
if ("" + prop.key == key) {
if (!all(props, function(prop) {
return prop instanceof AST.ObjectKeyVal;
})) break;
var value = prop.value;
if (value instanceof AST.Function
&& !(compressor.parent() instanceof AST.New)
&& value.contains_this()) break;
return make_node(AST.Sub, this, {
expression: make_node(AST.Array, expr, {
elements: props.map(function(prop) {
return prop.value;
})
}),
property: make_node(AST.Number, this, {
value: i
})
});
}
}
}
});
OPT(AST.Dot, function(self, compressor) {
if (self.property == "arguments" || self.property == "caller") {
compressor.warn("Function.protoype.{prop} not supported [{file}:{line},{col}]", {
prop: self.property,
file: self.start.file,
line: self.start.line,
col: self.start.col
});
}
var def = self.resolve_defines(compressor);
if (def) {
return def.optimize(compressor);
}
if (is_lhs(self, compressor.parent())) return self;
if (compressor.option("unsafe_proto")
&& self.expression instanceof AST.Dot
&& self.expression.property == "prototype") {
var exp = self.expression.expression;
if (is_undeclared_ref(exp)) switch (exp.name) {
case "Array":
self.expression = make_node(AST.Array, self.expression, {
elements: []
});
break;
case "Function":
self.expression = make_node(AST.Function, self.expression, {
argnames: [],
body: []
});
break;
case "Number":
self.expression = make_node(AST.Number, self.expression, {
value: 0
});
break;
case "Object":
self.expression = make_node(AST.Object, self.expression, {
properties: []
});
break;
case "RegExp":
self.expression = make_node(AST.RegExp, self.expression, {
value: /t/
});
break;
case "String":
self.expression = make_node(AST.String, self.expression, {
value: ""
});
break;
}
}
var sub = self.flatten_object(self.property, compressor);
if (sub) return sub.optimize(compressor);
var ev = self.evaluate(compressor);
if (ev !== self) {
ev = make_node_from_constant(ev, self).optimize(compressor);
return best_of(compressor, ev, self);
}
return self;
});
OPT(AST.Return, function(self, compressor) {
if (self.value && is_undefined(self.value, compressor)) {
self.value = null;
}
return self;
});
OPT(AST.VarDef, function(self, compressor) {
var defines = compressor.option("global_defs");
if (defines && HOP(defines, self.name.name)) {
compressor.warn('global_defs ' + self.name.name + ' redefined [{file}:{line},{col}]', self.start);
}
return self;
});
})(function(node, optimizer) {
node.DEFMETHOD("optimize", function(compressor) {
var self = this;
if (self._optimized) return self;
if (compressor.has_directive("use asm")) return self;
var opt = optimizer(self, compressor);
opt._optimized = true;
return opt;
});
});
merge(exports, {
Compressor : Compressor,
});
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