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https://github.com/denoland/deno.git
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242 lines
6.2 KiB
JavaScript
242 lines
6.2 KiB
JavaScript
// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
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// This code has been ported almost directly from Go's src/bytes/buffer.go
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// Copyright 2009 The Go Authors. All rights reserved. BSD license.
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// https://github.com/golang/go/blob/master/LICENSE
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"use strict";
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((window) => {
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const { assert } = window.__bootstrap.util;
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// MIN_READ is the minimum ArrayBuffer size passed to a read call by
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// buffer.ReadFrom. As long as the Buffer has at least MIN_READ bytes beyond
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// what is required to hold the contents of r, readFrom() will not grow the
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// underlying buffer.
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const MIN_READ = 32 * 1024;
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const MAX_SIZE = 2 ** 32 - 2;
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// `off` is the offset into `dst` where it will at which to begin writing values
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// from `src`.
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// Returns the number of bytes copied.
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function copyBytes(src, dst, off = 0) {
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const r = dst.byteLength - off;
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if (src.byteLength > r) {
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src = src.subarray(0, r);
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}
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dst.set(src, off);
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return src.byteLength;
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}
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class Buffer {
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#buf = null; // contents are the bytes buf[off : len(buf)]
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#off = 0; // read at buf[off], write at buf[buf.byteLength]
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constructor(ab) {
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if (ab == null) {
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this.#buf = new Uint8Array(0);
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return;
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}
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this.#buf = new Uint8Array(ab);
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}
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bytes(options = { copy: true }) {
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if (options.copy === false) return this.#buf.subarray(this.#off);
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return this.#buf.slice(this.#off);
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}
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empty() {
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return this.#buf.byteLength <= this.#off;
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}
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get length() {
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return this.#buf.byteLength - this.#off;
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}
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get capacity() {
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return this.#buf.buffer.byteLength;
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}
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truncate(n) {
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if (n === 0) {
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this.reset();
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return;
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}
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if (n < 0 || n > this.length) {
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throw Error("bytes.Buffer: truncation out of range");
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}
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this.#reslice(this.#off + n);
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}
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reset() {
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this.#reslice(0);
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this.#off = 0;
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}
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#tryGrowByReslice = (n) => {
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const l = this.#buf.byteLength;
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if (n <= this.capacity - l) {
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this.#reslice(l + n);
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return l;
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}
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return -1;
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};
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#reslice = (len) => {
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assert(len <= this.#buf.buffer.byteLength);
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this.#buf = new Uint8Array(this.#buf.buffer, 0, len);
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};
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readSync(p) {
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if (this.empty()) {
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// Buffer is empty, reset to recover space.
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this.reset();
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if (p.byteLength === 0) {
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// this edge case is tested in 'bufferReadEmptyAtEOF' test
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return 0;
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}
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return null;
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}
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const nread = copyBytes(this.#buf.subarray(this.#off), p);
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this.#off += nread;
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return nread;
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}
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read(p) {
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const rr = this.readSync(p);
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return Promise.resolve(rr);
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}
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writeSync(p) {
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const m = this.#grow(p.byteLength);
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return copyBytes(p, this.#buf, m);
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}
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write(p) {
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const n = this.writeSync(p);
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return Promise.resolve(n);
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}
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#grow = (n) => {
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const m = this.length;
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// If buffer is empty, reset to recover space.
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if (m === 0 && this.#off !== 0) {
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this.reset();
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}
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// Fast: Try to grow by means of a reslice.
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const i = this.#tryGrowByReslice(n);
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if (i >= 0) {
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return i;
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}
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const c = this.capacity;
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if (n <= Math.floor(c / 2) - m) {
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// We can slide things down instead of allocating a new
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// ArrayBuffer. We only need m+n <= c to slide, but
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// we instead let capacity get twice as large so we
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// don't spend all our time copying.
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copyBytes(this.#buf.subarray(this.#off), this.#buf);
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} else if (c + n > MAX_SIZE) {
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throw new Error("The buffer cannot be grown beyond the maximum size.");
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} else {
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// Not enough space anywhere, we need to allocate.
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const buf = new Uint8Array(Math.min(2 * c + n, MAX_SIZE));
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copyBytes(this.#buf.subarray(this.#off), buf);
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this.#buf = buf;
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}
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// Restore this.#off and len(this.#buf).
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this.#off = 0;
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this.#reslice(Math.min(m + n, MAX_SIZE));
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return m;
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};
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grow(n) {
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if (n < 0) {
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throw Error("Buffer.grow: negative count");
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}
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const m = this.#grow(n);
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this.#reslice(m);
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}
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async readFrom(r) {
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let n = 0;
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const tmp = new Uint8Array(MIN_READ);
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while (true) {
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const shouldGrow = this.capacity - this.length < MIN_READ;
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// read into tmp buffer if there's not enough room
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// otherwise read directly into the internal buffer
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const buf = shouldGrow
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? tmp
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: new Uint8Array(this.#buf.buffer, this.length);
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const nread = await r.read(buf);
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if (nread === null) {
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return n;
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}
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// write will grow if needed
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if (shouldGrow) this.writeSync(buf.subarray(0, nread));
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else this.#reslice(this.length + nread);
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n += nread;
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}
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}
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readFromSync(r) {
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let n = 0;
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const tmp = new Uint8Array(MIN_READ);
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while (true) {
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const shouldGrow = this.capacity - this.length < MIN_READ;
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// read into tmp buffer if there's not enough room
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// otherwise read directly into the internal buffer
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const buf = shouldGrow
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? tmp
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: new Uint8Array(this.#buf.buffer, this.length);
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const nread = r.readSync(buf);
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if (nread === null) {
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return n;
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}
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// write will grow if needed
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if (shouldGrow) this.writeSync(buf.subarray(0, nread));
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else this.#reslice(this.length + nread);
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n += nread;
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}
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}
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}
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async function readAll(r) {
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const buf = new Buffer();
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await buf.readFrom(r);
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return buf.bytes();
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}
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function readAllSync(r) {
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const buf = new Buffer();
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buf.readFromSync(r);
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return buf.bytes();
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}
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async function writeAll(w, arr) {
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let nwritten = 0;
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while (nwritten < arr.length) {
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nwritten += await w.write(arr.subarray(nwritten));
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}
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}
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function writeAllSync(w, arr) {
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let nwritten = 0;
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while (nwritten < arr.length) {
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nwritten += w.writeSync(arr.subarray(nwritten));
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}
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}
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window.__bootstrap.buffer = {
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writeAll,
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writeAllSync,
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readAll,
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readAllSync,
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Buffer,
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};
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})(this);
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