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support nullish coalescing operator (#4678)

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Alex Lam S.L 2021-02-23 21:57:11 +00:00 committed by GitHub
parent d68d155f93
commit c885660347
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16 changed files with 177 additions and 36 deletions
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2
README.md
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@ -85,7 +85,7 @@ a double dash to prevent input files being used as option arguments:
1 - single
2 - double
3 - original
`wrap_iife` Wrap IIFEs in parenthesis. Note: you may
`wrap_iife` Wrap IIFEs in parentheses. Note: you may
want to disable `negate_iife` under
compressor options.
-O, --output-opts [options] Specify output options (`beautify` disabled by default).

46
lib/compress.js
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@ -2182,6 +2182,7 @@ merge(Compressor.prototype, {
var lazy = lazy_op[expr.operator];
if (unused
&& lazy
&& expr.operator != "??"
&& expr.right instanceof AST_Assign
&& expr.right.operator == "="
&& !(expr.right.left instanceof AST_Destructured)) {
@ -3840,7 +3841,7 @@ merge(Compressor.prototype, {
node.DEFMETHOD("is_string", func);
});
var lazy_op = makePredicate("&& ||");
var lazy_op = makePredicate("&& || ??");
(function(def) {
function to_node(value, orig) {
@ -4286,6 +4287,9 @@ merge(Compressor.prototype, {
switch (this.operator) {
case "&&" : result = left && right; break;
case "||" : result = left || right; break;
case "??" :
result = left == null ? right : left;
break;
case "|" : result = left | right; break;
case "&" : result = left & right; break;
case "^" : result = left ^ right; break;
@ -7130,6 +7134,7 @@ merge(Compressor.prototype, {
node = this.clone();
node.right = right.drop_side_effect_free(compressor);
}
if (this.operator == "??") return node;
return (first_in_statement ? best_of_statement : best_of_expression)(node, make_node(AST_Binary, this, {
operator: node.operator == "&&" ? "||" : "&&",
left: node.left.negate(compressor, first_in_statement),
@ -9159,7 +9164,7 @@ merge(Compressor.prototype, {
// (a = b, x || a = c) ---> a = x ? b : c
function to_conditional_assignment(compressor, def, value, node) {
if (!(node instanceof AST_Binary)) return;
if (!lazy_op[node.operator]) return;
if (!(node.operator == "&&" || node.operator == "||")) return;
if (!(node.right instanceof AST_Assign)) return;
if (node.right.operator != "=") return;
if (!(node.right.left instanceof AST_SymbolRef)) return;
@ -9680,22 +9685,41 @@ merge(Compressor.prototype, {
}).optimize(compressor);
}
break;
case "??":
var nullish = true;
case "||":
var ll = fuzzy_eval(self.left);
if (!ll) {
AST_Node.warn("Condition left of || always false [{file}:{line},{col}]", self.start);
var ll = fuzzy_eval(self.left, nullish);
if (nullish ? ll == null : !ll) {
AST_Node.warn("Condition left of {operator} always {value} [{file}:{line},{col}]", {
operator: self.operator,
value: nullish ? "nulish" : "false",
file: self.start.file,
line: self.start.line,
col: self.start.col,
});
return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
} else if (!(ll instanceof AST_Node)) {
AST_Node.warn("Condition left of || always true [{file}:{line},{col}]", self.start);
AST_Node.warn("Condition left of {operator} always {value} [{file}:{line},{col}]", {
operator: self.operator,
value: nullish ? "defined" : "true",
file: self.start.file,
line: self.start.line,
col: self.start.col,
});
return maintain_this_binding(compressor, parent, compressor.self(), self.left).optimize(compressor);
}
var rr = self.right.evaluate(compressor);
if (!rr) {
if (in_bool || parent.operator == "||" && parent.left === compressor.self()) {
AST_Node.warn("Dropping side-effect-free || [{file}:{line},{col}]", self.start);
AST_Node.warn("Dropping side-effect-free {operator} [{file}:{line},{col}]", {
operator: self.operator,
file: self.start.file,
line: self.start.line,
col: self.start.col,
});
return self.left.optimize(compressor);
}
} else if (!(rr instanceof AST_Node)) {
} else if (!nullish && !(rr instanceof AST_Node)) {
if (in_bool) {
AST_Node.warn("Boolean || always true [{file}:{line},{col}]", self.start);
return make_sequence(self, [
@ -9705,7 +9729,7 @@ merge(Compressor.prototype, {
} else self.truthy = true;
}
// x && true || y ---> x ? true : y
if (self.left.operator == "&&") {
if (!nullish && self.left.operator == "&&") {
var lr = self.left.right.is_truthy() || self.left.right.evaluate(compressor, true);
if (lr && !(lr instanceof AST_Node)) return make_node(AST_Conditional, self, {
condition: self.left.left,
@ -10047,9 +10071,9 @@ merge(Compressor.prototype, {
});
}
function fuzzy_eval(node) {
function fuzzy_eval(node, nullish) {
if (node.truthy) return true;
if (node.falsy) return false;
if (node.falsy && !nullish) return false;
if (node.is_truthy()) return true;
return node.evaluate(compressor, true);
}

4
lib/output.js
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@ -753,7 +753,9 @@ function OutputStream(options) {
if (p instanceof AST_Binary) {
var po = p.operator, pp = PRECEDENCE[po];
var so = this.operator, sp = PRECEDENCE[so];
return pp > sp || (pp == sp && this === p[po == "**" ? "left" : "right"]);
return pp > sp
|| po == "??" && (so == "&&" || so == "||")
|| (pp == sp && this === p[po == "**" ? "left" : "right"]);
}
// (foo && bar)()
if (p instanceof AST_Call) return p.expression === this;

4
lib/parse.js
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@ -107,7 +107,8 @@ var OPERATORS = makePredicate([
"^=",
"&=",
"&&",
"||"
"||",
"??",
]);
var NEWLINE_CHARS = "\n\r\u2028\u2029";
@ -662,6 +663,7 @@ var PRECEDENCE = function(a, ret) {
}
return ret;
}([
["??"],
["||"],
["&&"],
["|"],

18
test/compress/arrows.js
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@ -34,7 +34,7 @@ destructured_funarg: {
node_version: ">=6"
}
await_parenthesis: {
await_parentheses: {
input: {
async function f() {
await (a => a);
@ -43,7 +43,7 @@ await_parenthesis: {
expect_exact: "async function f(){await(a=>a)}"
}
for_parenthesis_init: {
for_parentheses_init: {
input: {
for (a => (a in a); console.log(42););
}
@ -52,7 +52,7 @@ for_parenthesis_init: {
node_version: ">=4"
}
for_parenthesis_condition: {
for_parentheses_condition: {
input: {
for (console.log(42); a => (a in a);)
break;
@ -62,7 +62,7 @@ for_parenthesis_condition: {
node_version: ">=4"
}
for_parenthesis_step: {
for_parentheses_step: {
input: {
for (; console.log(42); a => (a in a));
}
@ -71,7 +71,7 @@ for_parenthesis_step: {
node_version: ">=4"
}
for_assign_parenthesis_init: {
for_assign_parentheses_init: {
input: {
for (f = a => (a in a); console.log(42););
}
@ -80,7 +80,7 @@ for_assign_parenthesis_init: {
node_version: ">=4"
}
for_assign_parenthesis_condition: {
for_assign_parentheses_condition: {
input: {
for (console.log(42); f = a => (a in a);)
break;
@ -90,7 +90,7 @@ for_assign_parenthesis_condition: {
node_version: ">=4"
}
for_assign_parenthesis_step: {
for_assign_parentheses_step: {
input: {
for (; console.log(42); f = a => (a in a));
}
@ -99,7 +99,7 @@ for_assign_parenthesis_step: {
node_version: ">=4"
}
for_declaration_parenthesis_init: {
for_declaration_parentheses_init: {
input: {
for (var f = a => (a in a); console.log(42););
}
@ -108,7 +108,7 @@ for_declaration_parenthesis_init: {
node_version: ">=4"
}
for_statement_parenthesis_init: {
for_statement_parentheses_init: {
input: {
for (a => {
a in a;

2
test/compress/classes.js
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@ -158,7 +158,7 @@ yield: {
node_version: ">=12"
}
conditional_parenthesis: {
conditional_parentheses: {
options = {
conditionals: true,
}

4
test/compress/exports.js
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@ -38,7 +38,7 @@ defaults: {
expect_exact: "export default 42;export default async;export default(x,y)=>x*x;export default class{}export default function*(a,b){}export default async function f({c:c},...[d]){}"
}
defaults_parenthesis_1: {
defaults_parentheses_1: {
input: {
export default function() {
console.log("FAIL");
@ -47,7 +47,7 @@ defaults_parenthesis_1: {
expect_exact: 'export default function(){console.log("FAIL")}console.log("PASS");'
}
defaults_parenthesis_2: {
defaults_parentheses_2: {
input: {
export default (async function() {
console.log("PASS");

2
test/compress/functions.js
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@ -2053,7 +2053,7 @@ issue_2898: {
expect_stdout: "2"
}
deduplicate_parenthesis: {
deduplicate_parentheses: {
input: {
({}).a = b;
(({}).a = b)();

4
test/compress/loops.js
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@ -501,14 +501,14 @@ do_switch: {
}
}
in_parenthesis_1: {
in_parentheses_1: {
input: {
for (("foo" in {});0;);
}
expect_exact: 'for(("foo"in{});0;);'
}
in_parenthesis_2: {
in_parentheses_2: {
input: {
for ((function(){ "foo" in {}; });0;);
}

4
test/compress/new.js
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@ -85,7 +85,7 @@ new_with_unary_prefix: {
expect_exact: 'var bar=(+new Date).toString(32);';
}
dot_parenthesis_1: {
dot_parentheses_1: {
input: {
console.log(new (Math.random().constructor) instanceof Number);
}
@ -93,7 +93,7 @@ dot_parenthesis_1: {
expect_stdout: "true"
}
dot_parenthesis_2: {
dot_parentheses_2: {
input: {
console.log(typeof new function(){Math.random()}.constructor);
}

111
test/compress/nullish.js Normal file
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@ -0,0 +1,111 @@
parentheses: {
input: {
(console.log("foo") || console.log("bar") ?? console.log("baz")) && console.log("moo");
}
expect_exact:'((console.log("foo")||console.log("bar"))??console.log("baz"))&&console.log("moo");'
expect_stdout: [
"foo",
"bar",
"baz",
]
node_version: ">=14"
}
evaluate: {
options = {
evaluate: true,
side_effects: true,
}
input: {
void console.log("foo" ?? "bar") ?? console.log("baz");
}
expect: {
console.log("foo"),
console.log("baz");
}
expect_stdout: [
"foo",
"baz",
]
node_version: ">=14"
}
conditional_assignment_1: {
options = {
collapse_vars: true,
}
input: {
console.log(function(a, b) {
b ?? (a = "FAIL");
return a;
}("PASS", !console));
}
expect: {
console.log(function(a, b) {
b ?? (a = "FAIL");
return a;
}("PASS", !console));
}
expect_stdout: "PASS"
node_version: ">=14"
}
conditional_assignment_2: {
options = {
conditionals: true,
}
input: {
var a, b = false;
a = "PASS",
b ?? (a = "FAIL"),
console.log(a);
}
expect: {
var a, b = false;
a = "PASS",
b ?? (a = "FAIL"),
console.log(a);
}
expect_stdout: "PASS"
node_version: ">=14"
}
conditional_assignment_3: {
options = {
conditionals: true,
join_vars: true,
}
input: {
var a, b = false;
a = "PASS",
b ?? (a = "FAIL"),
console.log(a);
}
expect: {
var a, b = false, a = "PASS";
b ?? (a = "FAIL"),
console.log(a);
}
expect_stdout: "PASS"
node_version: ">=14"
}
conditional_assignment_4: {
options = {
side_effects: true,
}
input: {
console.log(function(a) {
!console ?? (a = "FAIL");
return a;
}("PASS"));
}
expect: {
console.log(function(a) {
!console ?? (a = "FAIL");
return a;
}("PASS"));
}
expect_stdout: "PASS"
node_version: ">=14"
}

2
test/compress/numbers.js
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@ -777,7 +777,7 @@ issue_1710: {
expect_stdout: true
}
unary_binary_parenthesis: {
unary_binary_parentheses: {
options = {
evaluate: true,
}

4
test/compress/templates.js
View File

@ -53,7 +53,7 @@ tagged_chain: {
node_version: ">=4"
}
tag_parenthesis_arrow: {
tag_parentheses_arrow: {
input: {
console.log((s => s.raw[0])`\tPASS`.slice(2));
}
@ -62,7 +62,7 @@ tag_parenthesis_arrow: {
node_version: ">=4"
}
tag_parenthesis_new: {
tag_parentheses_new: {
input: {
(new function() {
return console.log;

2
test/mocha/comments.js
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@ -259,7 +259,7 @@ describe("comments", function() {
assert.strictEqual(result.code, code);
});
it("Should handle comments around parenthesis correctly", function() {
it("Should handle comments around parentheses correctly", function() {
var code = [
"a();",
"/* foo */",

2
test/mocha/parentheses.js
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@ -84,7 +84,7 @@ describe("parentheses", function() {
}
});
it("Should compress leading parenthesis with reasonable performance", function() {
it("Should compress leading parentheses with reasonable performance", function() {
this.timeout(30000);
var code = [
"({}?0:1)&&x();",

2
test/ufuzz/index.js
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@ -149,6 +149,7 @@ var SUPPORT = function(matrix) {
for_of: "for (var a of []);",
generator: "function* f(){}",
let: "let a;",
nullish: "0 ?? 0",
rest: "var [...a] = [];",
rest_object: "var {...a} = {};",
spread: "[...[]];",
@ -231,6 +232,7 @@ var BINARY_OPS = [
",",
];
BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
if (SUPPORT.nullish) BINARY_OPS.push("??");
BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
if (SUPPORT.exponentiation) BINARY_OPS.push("**");