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denoland-deno/ext/web/08_text_encoding.js

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JavaScript

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// @ts-check
/// <reference path="../../core/lib.deno_core.d.ts" />
/// <reference path="../../core/internal.d.ts" />
/// <reference path="../webidl/internal.d.ts" />
/// <reference path="../fetch/lib.deno_fetch.d.ts" />
/// <reference path="../web/internal.d.ts" />
/// <reference path="../web/lib.deno_web.d.ts" />
/// <reference lib="esnext" />
const core = globalThis.Deno.core;
const ops = core.ops;
import * as webidl from "ext:deno_webidl/00_webidl.js";
const primordials = globalThis.__bootstrap.primordials;
const {
DataViewPrototypeGetBuffer,
DataViewPrototypeGetByteLength,
DataViewPrototypeGetByteOffset,
PromiseReject,
PromiseResolve,
// TODO(lucacasonato): add SharedArrayBuffer to primordials
// SharedArrayBufferPrototype
StringPrototypeCharCodeAt,
StringPrototypeSlice,
TypedArrayPrototypeSubarray,
TypedArrayPrototypeGetBuffer,
TypedArrayPrototypeGetByteLength,
TypedArrayPrototypeGetByteOffset,
TypedArrayPrototypeGetSymbolToStringTag,
Uint8Array,
ObjectPrototypeIsPrototypeOf,
ArrayBufferIsView,
Uint32Array,
} = primordials;
class TextDecoder {
/** @type {string} */
#encoding;
/** @type {boolean} */
#fatal;
/** @type {boolean} */
#ignoreBOM;
/** @type {boolean} */
#utf8SinglePass;
/** @type {number | null} */
#rid = null;
/**
* @param {string} label
* @param {TextDecoderOptions} options
*/
constructor(label = "utf-8", options = {}) {
const prefix = "Failed to construct 'TextDecoder'";
label = webidl.converters.DOMString(label, prefix, "Argument 1");
options = webidl.converters.TextDecoderOptions(
options,
prefix,
"Argument 2",
);
const encoding = ops.op_encoding_normalize_label(label);
this.#encoding = encoding;
this.#fatal = options.fatal;
this.#ignoreBOM = options.ignoreBOM;
this.#utf8SinglePass = encoding === "utf-8" && !options.fatal;
this[webidl.brand] = webidl.brand;
}
/** @returns {string} */
get encoding() {
webidl.assertBranded(this, TextDecoderPrototype);
return this.#encoding;
}
/** @returns {boolean} */
get fatal() {
webidl.assertBranded(this, TextDecoderPrototype);
return this.#fatal;
}
/** @returns {boolean} */
get ignoreBOM() {
webidl.assertBranded(this, TextDecoderPrototype);
return this.#ignoreBOM;
}
/**
* @param {BufferSource} [input]
* @param {TextDecodeOptions} options
*/
decode(input = new Uint8Array(), options = undefined) {
webidl.assertBranded(this, TextDecoderPrototype);
const prefix = "Failed to execute 'decode' on 'TextDecoder'";
if (input !== undefined) {
input = webidl.converters.BufferSource(input, prefix, "Argument 1", {
allowShared: true,
});
}
let stream = false;
if (options !== undefined) {
options = webidl.converters.TextDecodeOptions(
options,
prefix,
"Argument 2",
);
stream = options.stream;
}
try {
/** @type {ArrayBufferLike} */
let buffer = input;
if (ArrayBufferIsView(input)) {
if (TypedArrayPrototypeGetSymbolToStringTag(input) !== undefined) {
// TypedArray
buffer = TypedArrayPrototypeGetBuffer(
/** @type {Uint8Array} */ (input),
);
} else {
// DataView
buffer = DataViewPrototypeGetBuffer(/** @type {DataView} */ (input));
}
}
// Note from spec: implementations are strongly encouraged to use an implementation strategy that avoids this copy.
// When doing so they will have to make sure that changes to input do not affect future calls to decode().
if (
ObjectPrototypeIsPrototypeOf(
// deno-lint-ignore prefer-primordials
SharedArrayBuffer.prototype,
buffer,
)
) {
// We clone the data into a non-shared ArrayBuffer so we can pass it
// to Rust.
// `input` is now a Uint8Array, and calling the TypedArray constructor
// with a TypedArray argument copies the data.
if (ArrayBufferIsView(input)) {
if (TypedArrayPrototypeGetSymbolToStringTag(input) !== undefined) {
// TypedArray
input = new Uint8Array(
buffer,
TypedArrayPrototypeGetByteOffset(
/** @type {Uint8Array} */ (input),
),
TypedArrayPrototypeGetByteLength(
/** @type {Uint8Array} */ (input),
),
);
} else {
// DataView
input = new Uint8Array(
buffer,
DataViewPrototypeGetByteOffset(/** @type {DataView} */ (input)),
DataViewPrototypeGetByteLength(/** @type {DataView} */ (input)),
);
}
} else {
input = new Uint8Array(buffer);
}
}
// Fast path for single pass encoding.
if (!stream && this.#rid === null) {
// Fast path for utf8 single pass encoding.
if (this.#utf8SinglePass) {
return ops.op_encoding_decode_utf8(input, this.#ignoreBOM);
}
return ops.op_encoding_decode_single(
input,
this.#encoding,
this.#fatal,
this.#ignoreBOM,
);
}
if (this.#rid === null) {
this.#rid = ops.op_encoding_new_decoder(
this.#encoding,
this.#fatal,
this.#ignoreBOM,
);
}
return ops.op_encoding_decode(input, this.#rid, stream);
} finally {
if (!stream && this.#rid !== null) {
core.close(this.#rid);
this.#rid = null;
}
}
}
}
webidl.configurePrototype(TextDecoder);
const TextDecoderPrototype = TextDecoder.prototype;
class TextEncoder {
constructor() {
this[webidl.brand] = webidl.brand;
}
/** @returns {string} */
get encoding() {
webidl.assertBranded(this, TextEncoderPrototype);
return "utf-8";
}
/**
* @param {string} input
* @returns {Uint8Array}
*/
encode(input = "") {
webidl.assertBranded(this, TextEncoderPrototype);
// The WebIDL type of `input` is `USVString`, but `core.encode` already
// converts lone surrogates to the replacement character.
input = webidl.converters.DOMString(
input,
"Failed to execute 'encode' on 'TextEncoder'",
"Argument 1",
);
return core.encode(input);
}
/**
* @param {string} source
* @param {Uint8Array} destination
* @returns {TextEncoderEncodeIntoResult}
*/
encodeInto(source, destination) {
webidl.assertBranded(this, TextEncoderPrototype);
const prefix = "Failed to execute 'encodeInto' on 'TextEncoder'";
// The WebIDL type of `source` is `USVString`, but the ops bindings
// already convert lone surrogates to the replacement character.
source = webidl.converters.DOMString(source, prefix, "Argument 1");
destination = webidl.converters.Uint8Array(
destination,
prefix,
"Argument 2",
{
allowShared: true,
},
);
ops.op_encoding_encode_into(source, destination, encodeIntoBuf);
return {
read: encodeIntoBuf[0],
written: encodeIntoBuf[1],
};
}
}
const encodeIntoBuf = new Uint32Array(2);
webidl.configurePrototype(TextEncoder);
const TextEncoderPrototype = TextEncoder.prototype;
class TextDecoderStream {
/** @type {TextDecoder} */
#decoder;
/** @type {TransformStream<BufferSource, string>} */
#transform;
/**
* @param {string} label
* @param {TextDecoderOptions} options
*/
constructor(label = "utf-8", options = {}) {
const prefix = "Failed to construct 'TextDecoderStream'";
label = webidl.converters.DOMString(label, prefix, "Argument 1");
options = webidl.converters.TextDecoderOptions(
options,
prefix,
"Argument 2",
);
this.#decoder = new TextDecoder(label, options);
this.#transform = new TransformStream({
// The transform and flush functions need access to TextDecoderStream's
// `this`, so they are defined as functions rather than methods.
transform: (chunk, controller) => {
try {
chunk = webidl.converters.BufferSource(chunk, prefix, "chunk", {
allowShared: true,
});
const decoded = this.#decoder.decode(chunk, { stream: true });
if (decoded) {
controller.enqueue(decoded);
}
return PromiseResolve();
} catch (err) {
return PromiseReject(err);
}
},
flush: (controller) => {
try {
const final = this.#decoder.decode();
if (final) {
controller.enqueue(final);
}
return PromiseResolve();
} catch (err) {
return PromiseReject(err);
}
},
});
this[webidl.brand] = webidl.brand;
}
/** @returns {string} */
get encoding() {
webidl.assertBranded(this, TextDecoderStreamPrototype);
return this.#decoder.encoding;
}
/** @returns {boolean} */
get fatal() {
webidl.assertBranded(this, TextDecoderStreamPrototype);
return this.#decoder.fatal;
}
/** @returns {boolean} */
get ignoreBOM() {
webidl.assertBranded(this, TextDecoderStreamPrototype);
return this.#decoder.ignoreBOM;
}
/** @returns {ReadableStream<string>} */
get readable() {
webidl.assertBranded(this, TextDecoderStreamPrototype);
return this.#transform.readable;
}
/** @returns {WritableStream<BufferSource>} */
get writable() {
webidl.assertBranded(this, TextDecoderStreamPrototype);
return this.#transform.writable;
}
}
webidl.configurePrototype(TextDecoderStream);
const TextDecoderStreamPrototype = TextDecoderStream.prototype;
class TextEncoderStream {
/** @type {string | null} */
#pendingHighSurrogate = null;
/** @type {TransformStream<string, Uint8Array>} */
#transform;
constructor() {
this.#transform = new TransformStream({
// The transform and flush functions need access to TextEncoderStream's
// `this`, so they are defined as functions rather than methods.
transform: (chunk, controller) => {
try {
chunk = webidl.converters.DOMString(chunk);
if (chunk === "") {
return PromiseResolve();
}
if (this.#pendingHighSurrogate !== null) {
chunk = this.#pendingHighSurrogate + chunk;
}
const lastCodeUnit = StringPrototypeCharCodeAt(
chunk,
chunk.length - 1,
);
if (0xD800 <= lastCodeUnit && lastCodeUnit <= 0xDBFF) {
this.#pendingHighSurrogate = StringPrototypeSlice(chunk, -1);
chunk = StringPrototypeSlice(chunk, 0, -1);
} else {
this.#pendingHighSurrogate = null;
}
if (chunk) {
controller.enqueue(core.encode(chunk));
}
return PromiseResolve();
} catch (err) {
return PromiseReject(err);
}
},
flush: (controller) => {
try {
if (this.#pendingHighSurrogate !== null) {
controller.enqueue(new Uint8Array([0xEF, 0xBF, 0xBD]));
}
return PromiseResolve();
} catch (err) {
return PromiseReject(err);
}
},
});
this[webidl.brand] = webidl.brand;
}
/** @returns {string} */
get encoding() {
webidl.assertBranded(this, TextEncoderStreamPrototype);
return "utf-8";
}
/** @returns {ReadableStream<Uint8Array>} */
get readable() {
webidl.assertBranded(this, TextEncoderStreamPrototype);
return this.#transform.readable;
}
/** @returns {WritableStream<string>} */
get writable() {
webidl.assertBranded(this, TextEncoderStreamPrototype);
return this.#transform.writable;
}
}
webidl.configurePrototype(TextEncoderStream);
const TextEncoderStreamPrototype = TextEncoderStream.prototype;
webidl.converters.TextDecoderOptions = webidl.createDictionaryConverter(
"TextDecoderOptions",
[
{
key: "fatal",
converter: webidl.converters.boolean,
defaultValue: false,
},
{
key: "ignoreBOM",
converter: webidl.converters.boolean,
defaultValue: false,
},
],
);
webidl.converters.TextDecodeOptions = webidl.createDictionaryConverter(
"TextDecodeOptions",
[
{
key: "stream",
converter: webidl.converters.boolean,
defaultValue: false,
},
],
);
/**
* @param {Uint8Array} bytes
*/
function decode(bytes, encoding) {
const BOMEncoding = BOMSniff(bytes);
if (BOMEncoding !== null) {
encoding = BOMEncoding;
const start = BOMEncoding === "UTF-8" ? 3 : 2;
bytes = TypedArrayPrototypeSubarray(bytes, start);
}
return new TextDecoder(encoding).decode(bytes);
}
/**
* @param {Uint8Array} bytes
*/
function BOMSniff(bytes) {
if (bytes[0] === 0xEF && bytes[1] === 0xBB && bytes[2] === 0xBF) {
return "UTF-8";
}
if (bytes[0] === 0xFE && bytes[1] === 0xFF) return "UTF-16BE";
if (bytes[0] === 0xFF && bytes[1] === 0xFE) return "UTF-16LE";
return null;
}
export {
decode,
TextDecoder,
TextDecoderStream,
TextEncoder,
TextEncoderStream,
};