decc7b092a
This patch makes 'let' a contextual keyword in both strict and sloppy mode.
It behaves as a keyword when used at the beginning of a StatementListItem
or lexical declaration at the beginning of a for statement, if it is followed
by an identifier, [ or {. Implementing this change requires an extra token
look-ahead by the parser which is only invoked in certain cases (so as to
avoid parsing RegExps as ECMAScript tokens). This might result in a slowdown
of the scanner, but performance testing of this patch hasn't yet found much
of a regression.
BUG=v8:3305
LOG=Y
R=adamk,vogelheim
Review URL: https://codereview.chromium.org/1315673009
Cr-Commit-Position: refs/heads/master@{#30451}
65 lines
1.3 KiB
JavaScript
65 lines
1.3 KiB
JavaScript
// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --harmony-sloppy --harmony-sloppy-let --harmony-destructuring
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{
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assertThrows(function() { return let; }, ReferenceError);
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let let;
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let = 5;
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assertEquals(5, let);
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{ let let = 1; assertEquals(1, let); }
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assertEquals(5, let);
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}
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assertThrows(function() { return let; }, ReferenceError);
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(function() {
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var let, sum = 0;
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for (let in [1, 2, 3, 4]) sum += Number(let);
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assertEquals(6, sum);
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for (let let of [4, 5]) sum += let;
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assertEquals(15, sum);
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for (let let in [6]) sum += Number([6][let]);
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assertEquals(21, sum);
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for (let = 7; let < 8; let++) sum += let;
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assertEquals(28, sum);
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assertEquals(8, let);
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for (let let = 8; let < 9; let++) sum += let;
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assertEquals(36, sum);
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assertEquals(8, let);
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})()
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assertThrows(function() { return let; }, ReferenceError);
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{
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let obj = {};
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let {let} = {let() { return obj; }};
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let().x = 1;
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assertEquals(1, obj.x);
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}
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{
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let obj = {};
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let [let] = [function() { return obj; }];
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let().x = 1;
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assertEquals(1, obj.x);
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}
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(function() {
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function let() {
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return 1;
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}
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assertEquals(1, let());
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})()
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assertThrows('for (let of []) {}', SyntaxError);
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