/
writers.ts
43 lines (37 loc) · 1.08 KB
/
writers.ts
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// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
type Writer = Deno.Writer;
type WriterSync = Deno.WriterSync;
const decoder = new TextDecoder();
/** Writer utility for buffering string chunks */
export class StringWriter implements Writer, WriterSync {
private chunks: Uint8Array[] = [];
private byteLength = 0;
private cache: string | undefined;
constructor(private base: string = "") {
const c = new TextEncoder().encode(base);
this.chunks.push(c);
this.byteLength += c.byteLength;
}
write(p: Uint8Array): Promise<number> {
return Promise.resolve(this.writeSync(p));
}
writeSync(p: Uint8Array): number {
this.chunks.push(p);
this.byteLength += p.byteLength;
this.cache = undefined;
return p.byteLength;
}
toString(): string {
if (this.cache) {
return this.cache;
}
const buf = new Uint8Array(this.byteLength);
let offs = 0;
for (const chunk of this.chunks) {
buf.set(chunk, offs);
offs += chunk.byteLength;
}
this.cache = decoder.decode(buf);
return this.cache;
}
}