4c699e349a
using newly introduced ThinStrings, which store a pointer to the actual,
internalized string they represent.
BUG=v8:4520
(Previously landed as #42168 / af51befe69.
Review-Url: https://codereview.chromium.org/2549773002
Cr-Commit-Position: refs/heads/master@{#42193}
73 lines
1.8 KiB
JavaScript
73 lines
1.8 KiB
JavaScript
// Copyright 2016 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: --allow-natives-syntax
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function get_thin_string(a, b) {
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var str = a + b; // Make a ConsString.
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var o = {};
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o[str]; // Turn it into a ThinString.
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return str;
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}
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var str = get_thin_string("foo", "bar");
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var re = /.o+ba./;
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assertEquals(["foobar"], re.exec(str));
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assertEquals(["foobar"], re.exec(str));
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assertEquals(["foobar"], re.exec(str));
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function CheckCS() {
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assertEquals("o", str.substring(1, 2));
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assertEquals("f".charCodeAt(0), str.charCodeAt(0));
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assertEquals("f", str.split(/oo/)[0]);
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}
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CheckCS();
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%OptimizeFunctionOnNextCall(CheckCS);
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CheckCS();
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function CheckTF() {
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try {} catch(e) {} // Turbofan.
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assertEquals("o", str.substring(1, 2));
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assertEquals("f".charCodeAt(0), str.charCodeAt(0));
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assertEquals("f", str.split(/oo/)[0]);
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}
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CheckTF();
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%OptimizeFunctionOnNextCall(CheckTF);
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CheckTF();
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// Flat cons strings can point to a thin string.
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function get_cons_thin_string(a, b) {
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// Make a ConsString.
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var s = a + b;
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// Flatten it.
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s.endsWith("a");
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// Internalize the first part.
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var o = {};
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o[s];
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return s;
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}
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var s = get_cons_thin_string("__________", "@@@@@@@@@@a");
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s.match(/.*a/);
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assertEquals("________", s.substring(0, 8));
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// Sliced strings can have a thin string as their parent.
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function get_sliced_thin_string(a, b) {
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// Make a long thin string.
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var s = a + b;
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// Slice a substring out of it.
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var slice = s.substring(0, 20);
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// Make the original string thin.
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var o = {};
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o[s];
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return slice;
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}
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var t = get_sliced_thin_string("abcdefghijklmnopqrstuvwxyz",
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"abcdefghijklmnopqrstuvwxyz");
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assertEquals("abcdefghijklmnopqrst", decodeURI(t));
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