vue hello world项目
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3 years ago
'use strict';
const Assert = require('@hapi/hoek/lib/assert');
const Clone = require('@hapi/hoek/lib/clone');
const Common = require('./common');
const internals = {
max: 1000,
supported: new Set(['undefined', 'boolean', 'number', 'string'])
};
exports.provider = {
provision(options) {
return new internals.Cache(options);
}
};
// Least Recently Used (LRU) Cache
internals.Cache = class {
constructor(options = {}) {
Common.assertOptions(options, ['max']);
Assert(options.max === undefined || options.max && options.max > 0 && isFinite(options.max), 'Invalid max cache size');
this._max = options.max || internals.max;
this._map = new Map(); // Map of nodes by key
this._list = new internals.List(); // List of nodes (most recently used in head)
}
get length() {
return this._map.size;
}
set(key, value) {
if (key !== null &&
!internals.supported.has(typeof key)) {
return;
}
let node = this._map.get(key);
if (node) {
node.value = value;
this._list.first(node);
return;
}
node = this._list.unshift({ key, value });
this._map.set(key, node);
this._compact();
}
get(key) {
const node = this._map.get(key);
if (node) {
this._list.first(node);
return Clone(node.value);
}
}
_compact() {
if (this._map.size > this._max) {
const node = this._list.pop();
this._map.delete(node.key);
}
}
};
internals.List = class {
constructor() {
this.tail = null;
this.head = null;
}
unshift(node) {
node.next = null;
node.prev = this.head;
if (this.head) {
this.head.next = node;
}
this.head = node;
if (!this.tail) {
this.tail = node;
}
return node;
}
first(node) {
if (node === this.head) {
return;
}
this._remove(node);
this.unshift(node);
}
pop() {
return this._remove(this.tail);
}
_remove(node) {
const { next, prev } = node;
next.prev = prev;
if (prev) {
prev.next = next;
}
if (node === this.tail) {
this.tail = next;
}
node.prev = null;
node.next = null;
return node;
}
};