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// Ported to Deno from
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
type Reader = Deno.Reader;
/** OneByteReader returns a Reader that implements
* each non-empty Read by reading one byte from r.
*/
export class OneByteReader implements Reader {
constructor(readonly r: Reader) {}
read(p: Uint8Array): Promise<number | null> {
if (p.byteLength === 0) {
return Promise.resolve(0);
}
if (!(p instanceof Uint8Array)) {
throw Error("expected Uint8Array");
}
return Promise.resolve(this.r.read(p.subarray(0, 1)));
}
}
/** HalfReader returns a Reader that implements Read
* by reading half as many requested bytes from r.
*/
export class HalfReader implements Reader {
constructor(readonly r: Reader) {}
read(p: Uint8Array): Promise<number | null> {
if (!(p instanceof Uint8Array)) {
throw Error("expected Uint8Array");
}
const half = Math.floor((p.byteLength + 1) / 2);
return Promise.resolve(this.r.read(p.subarray(0, half)));
}
}
/** TimeoutReader returns `Deno.errors.TimedOut` on the second read
* with no data. Subsequent calls to read succeed.
*/
export class TimeoutReader implements Reader {
count = 0;
constructor(readonly r: Reader) {}
read(p: Uint8Array): Promise<number | null> {
this.count++;
if (this.count === 2) {
throw new Deno.errors.TimedOut();
}
return Promise.resolve(this.r.read(p));
}
}
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