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HashTable.js
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84 lines (76 loc) · 2.75 KB
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//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------
var failed = false;
var verifyMemoryUsage = false;
var maxHashTableSizeShift = 5;
var maxHashTableSize = 1 << maxHashTableSizeShift;
function createHashTable() {
var o = new Array(); // array so that we can transition its type handler to an ES5 array type handler
var elements = new Array(maxHashTableSize);
o.elementHash = function (i) {
return Math.abs(i) & (maxHashTableSize - 1);
};
o.add = function (i) {
var elementIndex = this.elementHash(i);
if(elements[elementIndex] !== undefined) {
// Delete up to 4 used elements to make room
for(var j = elementIndex; j < elementIndex + 4 && j < maxHashTableSize; ++j) {
var e = elements[j];
if(e === undefined)
continue;
var h = "h" + e;
assertAreEqual(e, this[h]);
elements[j] = undefined;
delete this[h];
}
}
elements[elementIndex] = i;
this["h" + i] = i;
};
o.verify = function () {
for(var i = 0; i < maxHashTableSize; ++i) {
var e = elements[i];
if(e !== undefined)
assertAreEqual(e, this["h" + e]);
}
for(var h in this) {
if(h[0] !== "h")
continue;
assertAreEqual(h, "h" + elements[this.elementHash(this[h])]);
}
};
return o;
}
function useAsHashTable(o, n) {
for(var i = 0; n === 0 || i !== n; i = (i + 1) | 0) {
for(var j = i; j !== (i + 4) | 0; j = (j + 1) | 0)
o.add(j);
if(!(i & 0xffff) && verifyMemoryUsage)
WScript.Echo(i);
}
o.verify();
}
var o = createHashTable();
useAsHashTable(o, verifyMemoryUsage ? 0 : 1024);
// Transition to a DictionaryTypeHandler
Object.defineProperty(
o,
"foo",
{ configurable: true, enumerable: true, get: function () { }, set: function (v) { } });
useAsHashTable(o, 1024);
// Transition to an ES5ArrayTypeHandler
Object.defineProperty(
o,
"0",
{ configurable: true, writable: false, enumerable: true });
useAsHashTable(o, 1024);
if(!failed)
WScript.Echo("pass");
function assertAreEqual(expected, actual) {
if(expected === actual)
return;
failed = true;
WScript.Echo("Expected: " + expected + ", Actual: " + actual);
}