node/lib/string_decoder.js at v17.9.1 · nodejs/node · GitHub

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// Copyright Joyent, Inc. and other Node contributors.

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to permit

// persons to whom the Software is furnished to do so, subject to the

// following conditions:

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN

// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,

// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

const {

ArrayBufferIsView,

ObjectDefineProperties,

Symbol,

TypedArrayPrototypeSubarray,

} = primordials;

const { Buffer } = require('buffer');

const {

kIncompleteCharactersStart,

kIncompleteCharactersEnd,

kMissingBytes,

kBufferedBytes,

kEncodingField,

kSize,

decode,

flush,

encodings

} = internalBinding('string_decoder');

const internalUtil = require('internal/util');

const {

ERR_INVALID_ARG_TYPE,

ERR_INVALID_THIS,

ERR_UNKNOWN_ENCODING

} = require('internal/errors').codes;

const isEncoding = Buffer[internalUtil.kIsEncodingSymbol];

const kNativeDecoder = Symbol('kNativeDecoder');

// Do not cache `Buffer.isEncoding` when checking encoding names as some

// modules monkey-patch it to support additional encodings

/**

* Normalize encoding notation

* @param {string} enc

* @returns {"utf8" | "utf16le" | "hex" | "ascii"

* | "base64" | "latin1" | "base64url"}

* @throws {TypeError} Throws an error when encoding is invalid

function normalizeEncoding(enc) {

const nenc = internalUtil.normalizeEncoding(enc);

if (nenc === undefined) {

if (Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc))

throw new ERR_UNKNOWN_ENCODING(enc);

return enc;

}

return nenc;

}

const encodingsMap = {};

for (let i = 0; i < encodings.length; ++i)

encodingsMap[encodings[i]] = i;

/**

* StringDecoder provides an interface for efficiently splitting a series of

* buffers into a series of JS strings without breaking apart multi-byte

* characters.

* @param {string} [encoding=utf-8]

function StringDecoder(encoding) {

this.encoding = normalizeEncoding(encoding);

this[kNativeDecoder] = Buffer.alloc(kSize);

this[kNativeDecoder][kEncodingField] = encodingsMap[this.encoding];

}

/**

* Returns a decoded string, omitting any incomplete multi-bytes

* characters at the end of the Buffer, or TypedArray, or DataView

* @param {string | Buffer | TypedArray | DataView} buf

* @returns {string}

* @throws {TypeError} Throws when buf is not in one of supported types

StringDecoder.prototype.write = function write(buf) {

if (typeof buf === 'string')

return buf;

if (!ArrayBufferIsView(buf))

throw new ERR_INVALID_ARG_TYPE('buf',

['Buffer', 'TypedArray', 'DataView'],

buf);

if (!this[kNativeDecoder]) {

throw new ERR_INVALID_THIS('StringDecoder');

}

return decode(this[kNativeDecoder], buf);

};

/**

* Returns any remaining input stored in the internal buffer as a string.

* After end() is called, the stringDecoder object can be reused for new

* input.

* @param {string | Buffer | TypedArray | DataView} [buf]

* @returns {string}

StringDecoder.prototype.end = function end(buf) {

let ret = '';

if (buf !== undefined)

ret = this.write(buf);

if (this[kNativeDecoder][kBufferedBytes] > 0)

ret += flush(this[kNativeDecoder]);

return ret;

};

/* Everything below this line is undocumented legacy stuff. */

/**

* @param {string | Buffer | TypedArray | DataView} buf

* @param {number} offset

* @returns {string}

StringDecoder.prototype.text = function text(buf, offset) {

this[kNativeDecoder][kMissingBytes] = 0;

this[kNativeDecoder][kBufferedBytes] = 0;

return this.write(buf.slice(offset));

};

ObjectDefineProperties(StringDecoder.prototype, {

lastChar: {

configurable: true,

enumerable: true,

get() {

return TypedArrayPrototypeSubarray(this[kNativeDecoder],

kIncompleteCharactersStart,

kIncompleteCharactersEnd);

}

lastNeed: {

configurable: true,

enumerable: true,

get() {

return this[kNativeDecoder][kMissingBytes];

}

lastTotal: {

configurable: true,

enumerable: true,

get() {

return this[kNativeDecoder][kBufferedBytes] +

this[kNativeDecoder][kMissingBytes];

}

});

exports.StringDecoder = StringDecoder;

node/lib/string_decoder.js at v17.9.1 · nodejs/node · GitHub

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