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unpack array rest elements when given a right hand array expression

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Sebastian McKenzie
2015-02-21 02:09:07 +11:00
parent 62556f6102
commit 299e462a29
3 changed files with 21 additions and 18 deletions
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18
lib/babel/transformation/transformers/es6/destructuring.js
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@@ -163,13 +163,16 @@ var hasRest = function (pattern) {
};
DestructuringTransformer.prototype.canUnpackArrayPattern = function (pattern, arr) {
// not an array so there's no way we can deal with this
if (!t.isArrayExpression(arr)) return false;
if (pattern.elements.length < arr.elements.length) return false;
// pattern has less elements than the array and doesn't have a rest so some
// elements wont be evaluated
if (pattern.elements.length < arr.elements.length && !hasRest(pattern)) return false;
// deopt on holes
for (var i = 0; i < pattern.elements.length; i++) {
var elem = pattern.elements[i];
if (!elem) return false; // hole
if (t.isRestElement(elem)) return false;
if (!pattern.elements[i]) return false;
}
return true;
@@ -177,7 +180,12 @@ DestructuringTransformer.prototype.canUnpackArrayPattern = function (pattern, ar
DestructuringTransformer.prototype.pushUnpackedArrayPattern = function (pattern, arr) {
for (var i = 0; i < pattern.elements.length; i++) {
this.push(pattern.elements[i], arr.elements[i]);
var elem = pattern.elements[i]
if (t.isRestElement(elem)) {
this.push(elem.argument, t.arrayExpression(arr.elements.slice(i)));
} else {
this.push(elem, arr.elements[i]);
}
}
};