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66 lines
1.5 KiB
TypeScript
66 lines
1.5 KiB
TypeScript
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// Forked from https://github.com/stardazed/sd-streams/tree/8928cf04b035fd02fb1340b7eb541c76be37e546
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// Copyright (c) 2018-Present by Arthur Langereis - @zenmumbler MIT
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/**
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* streams/queue - simple queue type with chunked array backing
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* Part of Stardazed
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* (c) 2018-Present by Arthur Langereis - @zenmumbler
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* https://github.com/stardazed/sd-streams
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*/
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const CHUNK_SIZE = 16384;
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export interface Queue<T> {
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push(t: T): void;
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shift(): T | undefined;
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front(): T | undefined;
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readonly length: number;
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}
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export class QueueImpl<T> implements Queue<T> {
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private readonly chunks_: T[][];
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private readChunk_: T[];
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private writeChunk_: T[];
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private length_: number;
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constructor() {
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this.chunks_ = [[]];
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this.readChunk_ = this.writeChunk_ = this.chunks_[0];
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this.length_ = 0;
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}
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push(t: T): void {
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this.writeChunk_.push(t);
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this.length_ += 1;
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if (this.writeChunk_.length === CHUNK_SIZE) {
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this.writeChunk_ = [];
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this.chunks_.push(this.writeChunk_);
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}
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}
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front(): T | undefined {
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if (this.length_ === 0) {
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return undefined;
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}
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return this.readChunk_[0];
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}
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shift(): T | undefined {
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if (this.length_ === 0) {
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return undefined;
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}
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const t = this.readChunk_.shift();
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this.length_ -= 1;
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if (this.readChunk_.length === 0 && this.readChunk_ !== this.writeChunk_) {
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this.chunks_.shift();
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this.readChunk_ = this.chunks_[0];
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}
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return t;
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}
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get length(): number {
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return this.length_;
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}
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}
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