* Create CacheMap class

* Add test
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toasted-nutbread 2020-08-09 13:15:56 -04:00 committed by GitHub
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3 changed files with 346 additions and 1 deletions

177
ext/mixed/js/cache-map.js Normal file
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/*
* Copyright (C) 2020 Yomichan Authors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/**
* Class which caches a map of values using an arbitrary length path,
* keeping the most recently accessed values.
*/
class CacheMap {
/**
* Creates a new CacheMap.
* @param maxCount The maximum number of entries able to be stored in the cache.
* @param create A function to create a value for the corresponding path.
* The signature is: create(...path)
*/
constructor(maxCount, create) {
if (!(
typeof maxCount === 'number' &&
Number.isFinite(maxCount) &&
maxCount >= 0 &&
Math.floor(maxCount) === maxCount
)) {
throw new Error('Invalid maxCount');
}
this._maxCount = maxCount;
this._create = create;
this._count = 0;
this._map = new Map();
this._listFirst = this._createNode(null, null);
this._listLast = this._createNode(null, null);
this._resetEndNodes();
}
/**
* Returns the number of items in the cache.
*/
get count() {
return this._count;
}
/**
* Returns the maximum number of items that can be added to the cache.
*/
get maxCount() {
return this._maxCount;
}
/**
* Gets an item at the given path, if it exists. Otherwise, creates a new item
* and adds it to the cache. If the count exceeds the maximum count, items will be removed.
* @param path Arguments corresponding to the key of the cache.
*/
get(...path) {
let ii = path.length;
if (ii === 0) { throw new Error('Invalid path'); }
let map = this._map;
let i = 0;
for (; i < ii; ++i) {
const map2 = map.get(path[i]);
if (typeof map2 === 'undefined') { break; }
map = map2;
}
if (i === ii) {
// Found (map is now a node)
this._updateRecency(map);
return map.value;
}
// Create new
const value = this._create(...path);
// Create mapping
--ii;
for (; i < ii; ++i) {
const map2 = new Map();
map.set(path[i], map2);
map = map2;
}
// Assign
const node = this._createNode(value, path);
this._addNode(node, this._listFirst);
map.set(path[ii], node);
++this._count;
this._updateCount();
return value;
}
/**
* Clears the cache.
*/
clear() {
this._map.clear();
this._count = 0;
this._resetEndNodes();
}
// Private
_updateRecency(node) {
this._removeNode(node);
this._addNode(node, this._listFirst);
}
_updateCount() {
for (let removeCount = this._count - this._maxCount; removeCount > 0; --removeCount) {
const node = this._listLast.previous;
this._removeNode(node);
this._removeMapping(node.path);
--this._count;
}
}
_createNode(value, path) {
return {value, path, previous: null, next: null};
}
_addNode(node, previous) {
const next = previous.next;
node.next = next;
node.previous = previous;
previous.next = node;
next.previous = node;
}
_removeNode(node) {
node.next.previous = node.previous;
node.previous.next = node.next;
}
_removeMapping(path) {
const ii = path.length - 1;
let i = 0;
const maps = [];
let map = this._map;
for (; i < ii; ++i) {
const map2 = map.get(path[i]);
if (typeof map2 === 'undefined') { return; }
maps.push([map, map2]);
map = map2;
}
// Delete node
map.delete(path[ii]);
// Clear empty paths
for (i = ii - 1; i >= 0; --i) {
let map2;
[map, map2] = maps[i];
if (map2.size > 0) { return; }
map.delete(path[i]);
}
}
_resetEndNodes() {
this._listFirst.next = this._listLast;
this._listLast.previous = this._listFirst;
}
}

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"build": "node ./dev/build.js", "build": "node ./dev/build.js",
"test": "npm run test-lint && npm run test-code && npm run test-manifest", "test": "npm run test-lint && npm run test-code && npm run test-manifest",
"test-lint": "eslint . && node ./test/lint/global-declarations.js", "test-lint": "eslint . && node ./test/lint/global-declarations.js",
"test-code": "node ./test/test-schema.js && node ./test/test-dictionary.js && node ./test/test-database.js && node ./test/test-document.js && node ./test/test-object-property-accessor.js && node ./test/test-japanese.js && node ./test/test-text-source-map.js && node ./test/test-dom-text-scanner.js", "test-code": "node ./test/test-schema.js && node ./test/test-dictionary.js && node ./test/test-database.js && node ./test/test-document.js && node ./test/test-object-property-accessor.js && node ./test/test-japanese.js && node ./test/test-text-source-map.js && node ./test/test-dom-text-scanner.js && node ./test/test-cache-map.js",
"test-manifest": "node ./test/test-manifest.js" "test-manifest": "node ./test/test-manifest.js"
}, },
"repository": { "repository": {

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test/test-cache-map.js Normal file
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/*
* Copyright (C) 2020 Yomichan Authors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
const assert = require('assert');
const {VM} = require('./yomichan-vm');
const vm = new VM({console});
vm.execute([
'mixed/js/cache-map.js'
]);
const CacheMap = vm.get('CacheMap');
function testConstructor() {
const data = [
[false, () => new CacheMap(0, () => null)],
[false, () => new CacheMap(1, () => null)],
[false, () => new CacheMap(Number.MAX_VALUE, () => null)],
[true, () => new CacheMap(-1, () => null)],
[true, () => new CacheMap(1.5, () => null)],
[true, () => new CacheMap(Number.NaN, () => null)],
[true, () => new CacheMap(Number.POSITIVE_INFINITY, () => null)],
[true, () => new CacheMap('a', () => null)]
];
for (const [throws, create] of data) {
if (throws) {
assert.throws(create);
} else {
assert.doesNotThrow(create);
}
}
}
function testApi() {
const data = [
{
maxCount: 1,
expectedCount: 0,
calls: []
},
{
maxCount: 1,
expectedCount: 1,
calls: [
['get', 'a', 'b', 'c']
]
},
{
maxCount: 10,
expectedCount: 1,
calls: [
['get', 'a', 'b', 'c'],
['get', 'a', 'b', 'c'],
['get', 'a', 'b', 'c']
]
},
{
maxCount: 10,
expectedCount: 3,
calls: [
['get', 'a1', 'b', 'c'],
['get', 'a2', 'b', 'c'],
['get', 'a3', 'b', 'c']
]
},
{
maxCount: 10,
expectedCount: 3,
calls: [
['get', 'a', 'b1', 'c'],
['get', 'a', 'b2', 'c'],
['get', 'a', 'b3', 'c']
]
},
{
maxCount: 10,
expectedCount: 3,
calls: [
['get', 'a', 'b', 'c1'],
['get', 'a', 'b', 'c2'],
['get', 'a', 'b', 'c3']
]
},
{
maxCount: 1,
expectedCount: 1,
calls: [
['get', 'a1', 'b', 'c'],
['get', 'a2', 'b', 'c'],
['get', 'a3', 'b', 'c']
]
},
{
maxCount: 1,
expectedCount: 1,
calls: [
['get', 'a', 'b1', 'c'],
['get', 'a', 'b2', 'c'],
['get', 'a', 'b3', 'c']
]
},
{
maxCount: 1,
expectedCount: 1,
calls: [
['get', 'a', 'b', 'c1'],
['get', 'a', 'b', 'c2'],
['get', 'a', 'b', 'c3']
]
},
{
maxCount: 10,
expectedCount: 0,
calls: [
['get', 'a', 'b', 'c1'],
['get', 'a', 'b', 'c2'],
['get', 'a', 'b', 'c3'],
['clear']
]
},
{
maxCount: 0,
expectedCount: 0,
calls: [
['get', 'a1', 'b', 'c'],
['get', 'a', 'b2', 'c'],
['get', 'a', 'b', 'c3']
]
}
];
const create = (...args) => args.join(',');
for (const {maxCount, expectedCount, calls} of data) {
const cache = new CacheMap(maxCount, create);
assert.strictEqual(cache.maxCount, maxCount);
for (const [name, ...args] of calls) {
switch (name) {
case 'get': cache.get(...args); break;
case 'clear': cache.clear(); break;
}
}
assert.strictEqual(cache.count, expectedCount);
}
}
function main() {
testConstructor();
testApi();
}
if (require.main === module) { main(); }