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std/io/buf_writer.ts

The Deno Standard Library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { copy } from "../bytes/copy.ts";import type { Writer, WriterSync } from "./types.ts";
const DEFAULT_BUF_SIZE = 4096;
abstract class AbstractBufBase { buf: Uint8Array; usedBufferBytes = 0; err: Error | null = null;
constructor(buf: Uint8Array) { this.buf = buf; }
/** Size returns the size of the underlying buffer in bytes. */ size(): number { return this.buf.byteLength; }
/** Returns how many bytes are unused in the buffer. */ available(): number { return this.buf.byteLength - this.usedBufferBytes; }
/** buffered returns the number of bytes that have been written into the * current buffer. */ buffered(): number { return this.usedBufferBytes; }}
/** BufWriter implements buffering for an deno.Writer object. * If an error occurs writing to a Writer, no more data will be * accepted and all subsequent writes, and flush(), will return the error. * After all data has been written, the client should call the * flush() method to guarantee all data has been forwarded to * the underlying deno.Writer. * * @deprecated (will be removed after 1.0.0) Use the {@link https://developer.mozilla.org/en-US/docs/Web/API/Streams_API | Web Streams API} instead. */export class BufWriter extends AbstractBufBase implements Writer { #writer: Writer;
/** return new BufWriter unless writer is BufWriter */ static create(writer: Writer, size: number = DEFAULT_BUF_SIZE): BufWriter { return writer instanceof BufWriter ? writer : new BufWriter(writer, size); }
constructor(writer: Writer, size: number = DEFAULT_BUF_SIZE) { super(new Uint8Array(size <= 0 ? DEFAULT_BUF_SIZE : size)); this.#writer = writer; }
/** Discards any unflushed buffered data, clears any error, and * resets buffer to write its output to w. */ reset(w: Writer) { this.err = null; this.usedBufferBytes = 0; this.#writer = w; }
/** Flush writes any buffered data to the underlying io.Writer. */ async flush() { if (this.err !== null) throw this.err; if (this.usedBufferBytes === 0) return;
try { const p = this.buf.subarray(0, this.usedBufferBytes); let nwritten = 0; while (nwritten < p.length) { nwritten += await this.#writer.write(p.subarray(nwritten)); } } catch (e) { if (e instanceof Error) { this.err = e; } throw e; }
this.buf = new Uint8Array(this.buf.length); this.usedBufferBytes = 0; }
/** Writes the contents of `data` into the buffer. If the contents won't fully * fit into the buffer, those bytes that are copied into the buffer will be flushed * to the writer and the remaining bytes are then copied into the now empty buffer. * * @return the number of bytes written to the buffer. */ async write(data: Uint8Array): Promise<number> { if (this.err !== null) throw this.err; if (data.length === 0) return 0;
let totalBytesWritten = 0; let numBytesWritten = 0; while (data.byteLength > this.available()) { if (this.buffered() === 0) { // Large write, empty buffer. // Write directly from data to avoid copy. try { numBytesWritten = await this.#writer.write(data); } catch (e) { if (e instanceof Error) { this.err = e; } throw e; } } else { numBytesWritten = copy(data, this.buf, this.usedBufferBytes); this.usedBufferBytes += numBytesWritten; await this.flush(); } totalBytesWritten += numBytesWritten; data = data.subarray(numBytesWritten); }
numBytesWritten = copy(data, this.buf, this.usedBufferBytes); this.usedBufferBytes += numBytesWritten; totalBytesWritten += numBytesWritten; return totalBytesWritten; }}
/** BufWriterSync implements buffering for a deno.WriterSync object. * If an error occurs writing to a WriterSync, no more data will be * accepted and all subsequent writes, and flush(), will return the error. * After all data has been written, the client should call the * flush() method to guarantee all data has been forwarded to * the underlying deno.WriterSync. * * @deprecated (will be removed after 1.0.0) Use the {@link https://developer.mozilla.org/en-US/docs/Web/API/Streams_API | Web Streams API} instead. */export class BufWriterSync extends AbstractBufBase implements WriterSync { #writer: WriterSync;
/** return new BufWriterSync unless writer is BufWriterSync */ static create( writer: WriterSync, size: number = DEFAULT_BUF_SIZE, ): BufWriterSync { return writer instanceof BufWriterSync ? writer : new BufWriterSync(writer, size); }
constructor(writer: WriterSync, size: number = DEFAULT_BUF_SIZE) { super(new Uint8Array(size <= 0 ? DEFAULT_BUF_SIZE : size)); this.#writer = writer; }
/** Discards any unflushed buffered data, clears any error, and * resets buffer to write its output to w. */ reset(w: WriterSync) { this.err = null; this.usedBufferBytes = 0; this.#writer = w; }
/** Flush writes any buffered data to the underlying io.WriterSync. */ flush() { if (this.err !== null) throw this.err; if (this.usedBufferBytes === 0) return;
try { const p = this.buf.subarray(0, this.usedBufferBytes); let nwritten = 0; while (nwritten < p.length) { nwritten += this.#writer.writeSync(p.subarray(nwritten)); } } catch (e) { if (e instanceof Error) { this.err = e; } throw e; }
this.buf = new Uint8Array(this.buf.length); this.usedBufferBytes = 0; }
/** Writes the contents of `data` into the buffer. If the contents won't fully * fit into the buffer, those bytes that can are copied into the buffer, the * buffer is the flushed to the writer and the remaining bytes are copied into * the now empty buffer. * * @return the number of bytes written to the buffer. */ writeSync(data: Uint8Array): number { if (this.err !== null) throw this.err; if (data.length === 0) return 0;
let totalBytesWritten = 0; let numBytesWritten = 0; while (data.byteLength > this.available()) { if (this.buffered() === 0) { // Large write, empty buffer. // Write directly from data to avoid copy. try { numBytesWritten = this.#writer.writeSync(data); } catch (e) { if (e instanceof Error) { this.err = e; } throw e; } } else { numBytesWritten = copy(data, this.buf, this.usedBufferBytes); this.usedBufferBytes += numBytesWritten; this.flush(); } totalBytesWritten += numBytesWritten; data = data.subarray(numBytesWritten); }
numBytesWritten = copy(data, this.buf, this.usedBufferBytes); this.usedBufferBytes += numBytesWritten; totalBytesWritten += numBytesWritten; return totalBytesWritten; }}