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support destructuring of catch variable (#4412)

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Alex Lam S.L 2020-12-19 12:28:38 +08:00 committed by GitHub
parent 0f55bd92f1
commit e6dd471f8f
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 120 additions and 50 deletions
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10
lib/ast.js
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@ -786,7 +786,7 @@ var AST_Try = DEFNODE("Try", "bcatch bfinally", {
var AST_Catch = DEFNODE("Catch", "argname", {
$documentation: "A `catch` node; only makes sense as part of a `try` statement",
$propdoc: {
argname: "[AST_SymbolCatch?] symbol for the exception, or null if not present",
argname: "[(AST_Destructured|AST_SymbolCatch)?] symbol for the exception, or null if not present",
},
walk: function(visitor) {
var node = this;
@ -796,9 +796,9 @@ var AST_Catch = DEFNODE("Catch", "argname", {
});
},
_validate: function() {
if (this.argname != null) {
if (!(this.argname instanceof AST_SymbolCatch)) throw new Error("argname must be AST_SymbolCatch");
}
if (this.argname != null) validate_destructured(this.argname, function(node) {
if (!(node instanceof AST_SymbolCatch)) throw new Error("argname must be AST_SymbolCatch");
});
},
}, AST_Block);
@ -868,7 +868,7 @@ var AST_Var = DEFNODE("Var", null, {
var AST_VarDef = DEFNODE("VarDef", "name value", {
$documentation: "A variable declaration; only appears in a AST_Definitions node",
$propdoc: {
name: "[AST_SymbolVar] name of the variable",
name: "[AST_Destructured|AST_SymbolVar] name of the variable",
value: "[AST_Node?] initializer, or null of there's no initializer"
},
walk: function(visitor) {

70
lib/compress.js
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@ -4949,11 +4949,13 @@ merge(Compressor.prototype, {
walk_body(node, tw);
pop();
if (node.bcatch) {
if (node.bcatch.argname) {
var def = node.bcatch.argname.definition();
if (node.bcatch.argname) node.bcatch.argname.mark_symbol(function(node) {
if (node instanceof AST_SymbolCatch) {
var def = node.definition();
references[def.id] = false;
if (def = def.redefined()) references[def.id] = false;
}
}, tw);
push();
if (node.bfinally) segment.block = node.bcatch;
walk_body(node.bcatch, tw);
@ -5317,6 +5319,34 @@ merge(Compressor.prototype, {
var unused_fn_names = [];
var calls_to_drop_args = [];
var fns_with_marked_args = [];
var trimmer = new TreeTransformer(function(node) {
if (node instanceof AST_DestructuredArray) {
var trim = true;
for (var i = node.elements.length; --i >= 0;) {
var sym = node.elements[i];
if (!(sym instanceof AST_SymbolDeclaration)) {
node.elements[i] = sym.transform(trimmer);
trim = false;
} else if (sym.definition().id in in_use_ids) {
trim = false;
} else if (trim) {
node.elements.pop();
} else {
node.elements[i] = make_node(AST_Hole, sym);
}
}
return node;
}
if (node instanceof AST_DestructuredKeyVal) {
if (!(node.value instanceof AST_SymbolDeclaration)) {
node.value = node.value.transform(trimmer);
return node;
}
if (typeof node.key != "string") return node;
if (node.value.definition().id in in_use_ids) return node;
return List.skip;
}
});
var tt = new TreeTransformer(function(node, descend, in_list) {
var parent = tt.parent();
if (drop_vars) {
@ -5383,34 +5413,7 @@ merge(Compressor.prototype, {
for (var a = node.argnames, i = a.length; --i >= 0;) {
var sym = a[i];
if (sym instanceof AST_Destructured) {
sym.transform(new TreeTransformer(function(node) {
if (node instanceof AST_DestructuredArray) {
var trim = true;
for (var i = node.elements.length; --i >= 0;) {
var sym = node.elements[i];
if (!(sym instanceof AST_SymbolFunarg)) {
node.elements[i] = sym.transform(this);
trim = false;
} else if (sym.definition().id in in_use_ids) {
trim = false;
} else if (trim) {
node.elements.pop();
} else {
node.elements[i] = make_node(AST_Hole, sym);
}
}
return node;
}
if (node instanceof AST_DestructuredKeyVal) {
if (!(node.value instanceof AST_SymbolFunarg)) {
node.value = node.value.transform(this);
return node;
}
if (typeof node.key != "string") return node;
if (node.value.definition().id in in_use_ids) return node;
return List.skip;
}
}));
sym.transform(trimmer);
trim = false;
continue;
}
@ -5429,6 +5432,9 @@ merge(Compressor.prototype, {
fns_with_marked_args.push(node);
}
}
if (node instanceof AST_Catch && node.argname instanceof AST_Destructured) {
node.argname.transform(trimmer);
}
if (node instanceof AST_Definitions && !(parent instanceof AST_ForIn && parent.init === node)) {
// place uninitialized names at the start
var body = [], head = [], tail = [];
@ -7263,7 +7269,9 @@ merge(Compressor.prototype, {
self.body = tighten_body(self.body, compressor);
if (compressor.option("dead_code")) {
if (has_declarations_only(self)
&& !(self.bcatch && self.bcatch.argname && !can_drop_symbol(self.bcatch.argname))) {
&& !(self.bcatch && self.bcatch.argname && self.bcatch.argname.match_symbol(function(node) {
return node instanceof AST_SymbolCatch && !can_drop_symbol(node);
}, true))) {
var body = [];
if (self.bcatch) {
extract_declarations_from_unreachable_code(compressor, self.bcatch, body);

2
lib/parse.js
View File

@ -1216,7 +1216,7 @@ function parse($TEXT, options) {
var name = null;
if (is("punc", "(")) {
next();
name = as_symbol(AST_SymbolCatch);
name = maybe_destructured(AST_SymbolCatch);
expect(")");
}
bcatch = new AST_Catch({

40
test/compress/destructured.js
View File

@ -750,6 +750,46 @@ simple_var: {
node_version: ">=6"
}
drop_catch: {
options = {
dead_code: true,
}
input: {
try {} catch ({
[console.log("FAIL")]: e,
}) {} finally {
console.log("PASS");
}
}
expect: {
console.log("PASS");
}
expect_stdout: "PASS"
node_version: ">=6"
}
drop_catch_var: {
options = {
unused: true,
}
input: {
try {
throw new Error("PASS");
} catch ({ name, message }) {
console.log(message);
}
}
expect: {
try {
throw new Error("PASS");
} catch ({ message }) {
console.log(message);
}
}
expect_stdout: "PASS"
node_version: ">=6"
}
collapse_vars_1: {
options = {
collapse_vars: true,

40
test/ufuzz/index.js
View File

@ -858,22 +858,44 @@ function createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn
if (n !== 1) {
// the catch var should only be accessible in the catch clause...
// we have to do go through some trouble here to prevent leaking it
var nameLenBefore = VAR_NAMES.length;
mayCreateBlockVariables(recurmax, stmtDepth, canThrow, function(defns) {
if (SUPPORT.catch_omit_var && rng(20) == 0) {
var block_len = block_vars.length;
var nameLenBefore = VAR_NAMES.length;
var unique_len = unique_vars.length;
var offset = SUPPORT.catch_omit_var ? 0 : SUPPORT.destructuring ? 1 : 2;
switch (offset + rng(20 - offset)) {
case 0:
s += " catch { ";
break;
case 1:
var name = createVarName(MANDATORY);
block_vars.push(name);
var message = createVarName(MANDATORY);
block_vars.push(message);
if (SUPPORT.computed_key && rng(10) == 0) {
s += " catch ({ message: " + message + ", ";
addAvoidVars([ name ]);
s += "[" + createExpression(recurmax, NO_COMMA, stmtDepth, canThrow) + "]: " + name;
removeAvoidVars([ name ]);
s += " }) { ";
} else {
var catchName = createVarName(MANDATORY);
if (!catch_redef) unique_vars.push(catchName);
s += " catch (" + catchName + ") { ";
s += " catch ({ name: " + name + ", message: " + message + " }) { ";
}
var freshCatchName = VAR_NAMES.length !== nameLenBefore;
break;
default:
var name = createVarName(MANDATORY);
if (!catch_redef) unique_vars.push(name);
s += " catch (" + name + ") { ";
break;
}
var catches = VAR_NAMES.length - nameLenBefore;
s += defns() + "\n";
s += _createStatements(3, recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth);
s += " }";
// remove catch name
if (!catch_redef) unique_vars.pop();
if (freshCatchName) VAR_NAMES.splice(nameLenBefore, 1);
// remove catch variables
block_vars.length = block_len;
if (catches > 0) VAR_NAMES.splice(nameLenBefore, catches);
unique_vars.length = unique_len;
});
}
if (n !== 0) s += " finally { " + createStatements(3, recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth) + " }";