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RFC: Support iterables in dangerous for-of loops #8

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RFC: Support iterables in dangerous for-of loops #8

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11 changes: 7 additions & 4 deletions src/program/types/ForOfStatement.js
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Original file line number Diff line number Diff line change
Expand Up @@ -33,10 +33,11 @@ export default class ForOfStatement extends LoopStatement {

const key = scope.createIdentifier( 'i' );
const list = scope.createIdentifier( 'list' );
const useLen = scope.createIdentifier( 'useLen' );

if ( this.body.synthetic ) {
code.insertRight( this.left.start, `{\n${i1}` );
code.insertLeft( this.body.body[0].end, `\n${i0}}` );
code.insertLeft( this.body.end, `\n${i0}}` );
}

const bodyStart = this.body.body[0].start;
Expand All @@ -46,7 +47,9 @@ export default class ForOfStatement extends LoopStatement {


code.insertRight( this.right.start, `var ${key} = 0, ${list} = ` );
code.insertLeft( this.right.end, `; ${key} < ${list}.length; ${key} += 1` );
code.insertLeft( this.right.end, `, ${useLen} = typeof ${list}.length === 'number' || typeof Symbol !== 'function', ${list} = ${useLen} ? ${list} : ${list}[Symbol.iterator](); ${useLen} ? ${key} < ${list}.length : !(${key} = ${list}.next()).done;` );

const getVal = `${useLen} ? ${list}[${key}++] : ${key}.value`;

// destructuring. TODO non declaration destructuring
const declarator = this.left.type === 'VariableDeclaration' && this.left.declarations[0];
Expand All @@ -65,9 +68,9 @@ export default class ForOfStatement extends LoopStatement {
});

code.insertLeft( this.left.start + this.left.kind.length + 1, ref );
code.insertLeft( this.left.end, ` = ${list}[${key}];\n${i1}` );
code.insertLeft( this.left.end, ` = ${getVal};\n${i1}` );
} else {
code.insertLeft( this.left.end, ` = ${list}[${key}];\n\n${i1}` );
code.insertLeft( this.left.end, ` = ${getVal};\n\n${i1}` );
}

super.transpile( code, transforms );
Expand Down
36 changes: 18 additions & 18 deletions test/samples/for-of.js
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Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,8 @@ module.exports = [
}`,

output: `
for ( var i = 0, list = array; i < list.length; i += 1 ) {
var member = list[i];
for ( var i = 0, list = array, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) {
var member = useLen ? list[i++] : i.value;

doSomething( member );
}`
Expand All @@ -39,8 +39,8 @@ module.exports = [
}`,

output: `
for ( var i = 0, list = [ 'a', 'b', 'c' ]; i < list.length; i += 1 ) {
var member = list[i];
for ( var i = 0, list = [ 'a', 'b', 'c' ], useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) {
var member = useLen ? list[i++] : i.value;

doSomething( member );
}`
Expand All @@ -59,14 +59,14 @@ module.exports = [

output: `
var loop = function () {
var member = list[i];
var member = useLen ? list[i++] : i.value;

setTimeout( function () {
doSomething( member );
});
};

for ( var i = 0, list = [ 'a', 'b', 'c' ]; i < list.length; i += 1 ) loop();`
for ( var i = 0, list = [ 'a', 'b', 'c' ], useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) loop();`
},

{
Expand All @@ -77,8 +77,8 @@ module.exports = [
for ( let member of array ) console.log( member );`,

output: `
for ( var i = 0, list = array; i < list.length; i += 1 ) {
var member = list[i];
for ( var i = 0, list = array, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) {
var member = useLen ? list[i++] : i.value;

console.log( member );
}`
Expand All @@ -94,8 +94,8 @@ module.exports = [
}`,

output: `
for (var i = 0, list = this.keys; i < list.length; i += 1) {
var key = list[i];
for (var i = 0, list = this.keys, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done;) {
var key = useLen ? list[i++] : i.value;

console.log(key);
}`
Expand All @@ -111,8 +111,8 @@ module.exports = [
}`,

output: `
for ( var i = 0, list = items; i < list.length; i += 1 ) {
var item = list[i];
for ( var i = 0, list = items, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) {
var item = useLen ? list[i++] : i.value;

if ( item.foo ) { continue; }
}`
Expand All @@ -136,15 +136,15 @@ module.exports = [
var this$1 = this;

var loop = function () {
var item = list[i];
var item = useLen ? list[i++] : i.value;

console.log( this$1, arguments$1, item );
setTimeout( function () {
console.log( item );
});
};

for ( var i = 0, list = items; i < list.length; i += 1 ) loop();`
for ( var i = 0, list = items, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) loop();`
},

{
Expand Down Expand Up @@ -187,7 +187,7 @@ module.exports = [
output: `
function foo () {
var loop = function () {
var x = list[i];
var x = useLen ? list[i++] : i.value;

setTimeout( function () {
console.log( x );
Expand All @@ -196,7 +196,7 @@ module.exports = [
if ( x > 10 ) { return {}; }
};

for ( var i = 0, list = y; i < list.length; i += 1 ) {
for ( var i = 0, list = y, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done; ) {
var returned = loop();

if ( returned ) return returned.v;
Expand All @@ -214,8 +214,8 @@ module.exports = [
}`,

output: `
for (var i = 0, list = [{x: 1, y: 2}]; i < list.length; i += 1) {
var ref = list[i];
for (var i = 0, list = [{x: 1, y: 2}], useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done;) {
var ref = useLen ? list[i++] : i.value;
var x = ref.x;
var y = ref.y;

Expand Down
8 changes: 4 additions & 4 deletions test/samples/loops.js
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Original file line number Diff line number Diff line change
Expand Up @@ -504,8 +504,8 @@ module.exports = [
output: `
for (var a = 0; a < 10; a++) {
var j = 1, k = (void 0);
for (var i = 0, list = c; i < list.length; i += 1) {
var b = list[i];
for (var i = 0, list = c, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done;) {
var b = useLen ? list[i++] : i.value;

var x = (void 0), y = 2
f(b, j, k, x, y)
Expand All @@ -526,8 +526,8 @@ module.exports = [
}
`,
output: `
for (var i = 0, list = c; i < list.length; i += 1) {
var b = list[i];
for (var i = 0, list = c, useLen = typeof list.length === 'number' || typeof Symbol !== 'function', list = useLen ? list : list[Symbol.iterator](); useLen ? i < list.length : !(i = list.next()).done;) {
var b = useLen ? list[i++] : i.value;

var x = (void 0), y = 2, z = (void 0);
f(b, x++, y++, z++)
Expand Down