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add better optimization when strictMode transformer is enabled

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This commit is contained in:
Ondrej Kraus 2015-02-25 12:01:10 +01:00
parent e677c72d58
commit 1265bc5a92
1 changed files with 13 additions and 4 deletions
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17
src/babel/transformation/transformers/es6/parameters.rest.js
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@ -18,7 +18,8 @@ var memberExpressionVisitor = {
if (t.isMemberExpression(parent)) {
var prop = parent.property;
if (typeof prop.value === 'number' ||
if (state.strictMode ||
typeof prop.value === 'number' ||
t.isUnaryExpression(prop) ||
t.isBinaryExpression(prop)) {
state.candidates.push({ node: node, parent: parent });
@ -50,11 +51,17 @@ function optimizeMemberExpression(node, parent, offset) {
}
}
function optimizeMemberExpressionStrict(node, parent, offset) {
var prop = parent.property;
node.name = 'arguments';
parent.property = t.binaryExpression('+', prop, t.literal(offset));
}
var hasRest = function (node) {
return t.isRestElement(node.params[node.params.length - 1]);
};
exports.Function = function (node, parent, scope) {
exports.Function = function (node, parent, scope, file) {
if (!hasRest(node)) return;
var rest = node.params.pop().argument;
@ -81,14 +88,16 @@ exports.Function = function (node, parent, scope) {
name: rest.name,
outerDeclar: restOuterDeclar,
isOptimizable: true,
candidates: []
candidates: [],
strictMode: file.transformers.useStrict.canRun()
};
scope.traverse(node, memberExpressionVisitor, state);
if (state.isOptimizable) {
var optimize = state.strictMode ? optimizeMemberExpressionStrict : optimizeMemberExpression;
for (var i = 0, count = state.candidates.length; i < count; ++i) {
var candidate = state.candidates[i];
optimizeMemberExpression(candidate.node, candidate.parent, node.params.length);
optimize(candidate.node, candidate.parent, node.params.length);
}
return;
}