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linkedMap.ts
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linkedMap.ts
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/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
interface Item<K, V> {
previous: Item<K, V> | undefined;
next: Item<K, V> | undefined;
key: K;
value: V;
}
export namespace Touch {
export const None: 0 = 0;
export const First: 1 = 1;
export const AsOld: 1 = Touch.First;
export const Last: 2 = 2;
export const AsNew: 2 = Touch.Last;
}
export type Touch = 0 | 1 | 2;
export class LinkedMap<K, V> implements Map<K, V> {
readonly [Symbol.toStringTag] = 'LinkedMap';
private _map: Map<K, Item<K, V>>;
private _head: Item<K, V> | undefined;
private _tail: Item<K, V> | undefined;
private _size: number;
private _state: number;
public constructor() {
this._map = new Map<K, Item<K, V>>();
this._head = undefined;
this._tail = undefined;
this._size = 0;
this._state = 0;
}
public clear(): void {
this._map.clear();
this._head = undefined;
this._tail = undefined;
this._size = 0;
this._state++;
}
public isEmpty(): boolean {
return !this._head && !this._tail;
}
public get size(): number {
return this._size;
}
public get first(): V | undefined {
return this._head?.value;
}
public get last(): V | undefined {
return this._tail?.value;
}
public before(key: K): V | undefined {
const item = this._map.get(key);
return item ? item.previous?.value : undefined;
}
public after(key: K): V | undefined {
const item = this._map.get(key);
return item ? item.next?.value : undefined;
}
public has(key: K): boolean {
return this._map.has(key);
}
public get(key: K, touch: Touch = Touch.None): V | undefined {
const item = this._map.get(key);
if (!item) {
return undefined;
}
if (touch !== Touch.None) {
this.touch(item, touch);
}
return item.value;
}
public set(key: K, value: V, touch: Touch = Touch.None): this {
let item = this._map.get(key);
if (item) {
item.value = value;
if (touch !== Touch.None) {
this.touch(item, touch);
}
} else {
item = { key, value, next: undefined, previous: undefined };
switch (touch) {
case Touch.None:
this.addItemLast(item);
break;
case Touch.First:
this.addItemFirst(item);
break;
case Touch.Last:
this.addItemLast(item);
break;
default:
this.addItemLast(item);
break;
}
this._map.set(key, item);
this._size++;
}
return this;
}
public delete(key: K): boolean {
return !!this.remove(key);
}
public remove(key: K): V | undefined {
const item = this._map.get(key);
if (!item) {
return undefined;
}
this._map.delete(key);
this.removeItem(item);
this._size--;
return item.value;
}
public shift(): V | undefined {
if (!this._head && !this._tail) {
return undefined;
}
if (!this._head || !this._tail) {
throw new Error('Invalid list');
}
const item = this._head;
this._map.delete(item.key);
this.removeItem(item);
this._size--;
return item.value;
}
public forEach(callbackfn: (value: V, key: K, map: LinkedMap<K, V>) => void, thisArg?: any): void {
const state = this._state;
let current = this._head;
while (current) {
if (thisArg) {
callbackfn.bind(thisArg)(current.value, current.key, this);
} else {
callbackfn(current.value, current.key, this);
}
if (this._state !== state) {
throw new Error(`LinkedMap got modified during iteration.`);
}
current = current.next;
}
}
public keys(): IterableIterator<K> {
const state = this._state;
let current = this._head;
const iterator: IterableIterator<K> = {
[Symbol.iterator]: () => {
return iterator;
},
next: (): IteratorResult<K> => {
if (this._state !== state) {
throw new Error(`LinkedMap got modified during iteration.`);
}
if (current) {
const result = { value: current.key, done: false };
current = current.next;
return result;
} else {
return { value: undefined, done: true };
}
}
};
return iterator;
}
public values(): IterableIterator<V> {
const state = this._state;
let current = this._head;
const iterator: IterableIterator<V> = {
[Symbol.iterator]: () => {
return iterator;
},
next: (): IteratorResult<V> => {
if (this._state !== state) {
throw new Error(`LinkedMap got modified during iteration.`);
}
if (current) {
const result = { value: current.value, done: false };
current = current.next;
return result;
} else {
return { value: undefined, done: true };
}
}
};
return iterator;
}
public entries(): IterableIterator<[K, V]> {
const state = this._state;
let current = this._head;
const iterator: IterableIterator<[K, V]> = {
[Symbol.iterator]: () => {
return iterator;
},
next: (): IteratorResult<[K, V]> => {
if (this._state !== state) {
throw new Error(`LinkedMap got modified during iteration.`);
}
if (current) {
const result: IteratorResult<[K, V]> = { value: [current.key, current.value], done: false };
current = current.next;
return result;
} else {
return { value: undefined, done: true };
}
}
};
return iterator;
}
public [Symbol.iterator](): IterableIterator<[K, V]> {
return this.entries();
}
protected trimOld(newSize: number): void {
if (newSize >= this.size) {
return;
}
if (newSize === 0) {
this.clear();
return;
}
let current = this._head;
let currentSize = this.size;
while (current && currentSize > newSize) {
this._map.delete(current.key);
current = current.next;
currentSize--;
}
this._head = current;
this._size = currentSize;
if (current) {
current.previous = undefined;
}
this._state++;
}
private addItemFirst(item: Item<K, V>): void {
// First time Insert
if (!this._head && !this._tail) {
this._tail = item;
} else if (!this._head) {
throw new Error('Invalid list');
} else {
item.next = this._head;
this._head.previous = item;
}
this._head = item;
this._state++;
}
private addItemLast(item: Item<K, V>): void {
// First time Insert
if (!this._head && !this._tail) {
this._head = item;
} else if (!this._tail) {
throw new Error('Invalid list');
} else {
item.previous = this._tail;
this._tail.next = item;
}
this._tail = item;
this._state++;
}
private removeItem(item: Item<K, V>): void {
if (item === this._head && item === this._tail) {
this._head = undefined;
this._tail = undefined;
}
else if (item === this._head) {
// This can only happened if size === 1 which is handle
// by the case above.
if (!item.next) {
throw new Error('Invalid list');
}
item.next.previous = undefined;
this._head = item.next;
}
else if (item === this._tail) {
// This can only happened if size === 1 which is handle
// by the case above.
if (!item.previous) {
throw new Error('Invalid list');
}
item.previous.next = undefined;
this._tail = item.previous;
}
else {
const next = item.next;
const previous = item.previous;
if (!next || !previous) {
throw new Error('Invalid list');
}
next.previous = previous;
previous.next = next;
}
item.next = undefined;
item.previous = undefined;
this._state++;
}
private touch(item: Item<K, V>, touch: Touch): void {
if (!this._head || !this._tail) {
throw new Error('Invalid list');
}
if ((touch !== Touch.First && touch !== Touch.Last)) {
return;
}
if (touch === Touch.First) {
if (item === this._head) {
return;
}
const next = item.next;
const previous = item.previous;
// Unlink the item
if (item === this._tail) {
// previous must be defined since item was not head but is tail
// So there are more than on item in the map
previous!.next = undefined;
this._tail = previous;
}
else {
// Both next and previous are not undefined since item was neither head nor tail.
next!.previous = previous;
previous!.next = next;
}
// Insert the node at head
item.previous = undefined;
item.next = this._head;
this._head.previous = item;
this._head = item;
this._state++;
} else if (touch === Touch.Last) {
if (item === this._tail) {
return;
}
const next = item.next;
const previous = item.previous;
// Unlink the item.
if (item === this._head) {
// next must be defined since item was not tail but is head
// So there are more than on item in the map
next!.previous = undefined;
this._head = next;
} else {
// Both next and previous are not undefined since item was neither head nor tail.
next!.previous = previous;
previous!.next = next;
}
item.next = undefined;
item.previous = this._tail;
this._tail.next = item;
this._tail = item;
this._state++;
}
}
public toJSON(): [K, V][] {
const data: [K, V][] = [];
this.forEach((value, key) => {
data.push([key, value]);
});
return data;
}
public fromJSON(data: [K, V][]): void {
this.clear();
for (const [key, value] of data) {
this.set(key, value);
}
}
}
export class LRUCache<K, V> extends LinkedMap<K, V> {
private _limit: number;
private _ratio: number;
public constructor(limit: number, ratio: number = 1) {
super();
this._limit = limit;
this._ratio = Math.min(Math.max(0, ratio), 1);
}
public get limit(): number {
return this._limit;
}
public set limit(limit: number) {
this._limit = limit;
this.checkTrim();
}
public get ratio(): number {
return this._ratio;
}
public set ratio(ratio: number) {
this._ratio = Math.min(Math.max(0, ratio), 1);
this.checkTrim();
}
public get(key: K, touch: Touch = Touch.AsNew): V | undefined {
return super.get(key, touch);
}
public peek(key: K): V | undefined {
return super.get(key, Touch.None);
}
public set(key: K, value: V): this {
super.set(key, value, Touch.Last);
this.checkTrim();
return this;
}
private checkTrim() {
if (this.size > this._limit) {
this.trimOld(Math.round(this._limit * this._ratio));
}
}
}