1 // Copyright Joyent, Inc. and other Node contributors. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a 4 // copy of this software and associated documentation files (the 5 // "Software"), to deal in the Software without restriction, including 6 // without limitation the rights to use, copy, modify, merge, publish, 7 // distribute, sublicense, and/or sell copies of the Software, and to permit 8 // persons to whom the Software is furnished to do so, subject to the 9 // following conditions: 10 // 11 // The above copyright notice and this permission notice shall be included 12 // in all copies or substantial portions of the Software. 13 // 14 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 15 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 16 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN 17 // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 18 // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 19 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 20 // USE OR OTHER DEALINGS IN THE SOFTWARE. 21 22 'use strict'; 23 24 const { 25 ArrayBufferIsView, 26 ObjectDefineProperties, 27 Symbol, 28 TypedArrayPrototypeSubarray, 29 } = primordials; 30 31 const { Buffer } = require('buffer'); 32 const { 33 kIncompleteCharactersStart, 34 kIncompleteCharactersEnd, 35 kMissingBytes, 36 kBufferedBytes, 37 kEncodingField, 38 kSize, 39 decode, 40 flush, 41 encodings 42 } = internalBinding('string_decoder'); 43 const internalUtil = require('internal/util'); 44 const { 45 ERR_INVALID_ARG_TYPE, 46 ERR_UNKNOWN_ENCODING 47 } = require('internal/errors').codes; 48 const isEncoding = Buffer[internalUtil.kIsEncodingSymbol]; 49 50 const kNativeDecoder = Symbol('kNativeDecoder'); 51 52 // Do not cache `Buffer.isEncoding` when checking encoding names as some 53 // modules monkey-patch it to support additional encodings 54 function normalizeEncoding(enc) { 55 const nenc = internalUtil.normalizeEncoding(enc); 56 if (nenc === undefined) { 57 if (Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc)) 58 throw new ERR_UNKNOWN_ENCODING(enc); 59 return enc; 60 } 61 return nenc; 62 } 63 64 const encodingsMap = {}; 65 for (let i = 0; i < encodings.length; ++i) 66 encodingsMap[encodings[i]] = i; 67 68 // StringDecoder provides an interface for efficiently splitting a series of 69 // buffers into a series of JS strings without breaking apart multi-byte 70 // characters. 71 function StringDecoder(encoding) { 72 this.encoding = normalizeEncoding(encoding); 73 this[kNativeDecoder] = Buffer.alloc(kSize); 74 this[kNativeDecoder][kEncodingField] = encodingsMap[this.encoding]; 75 } 76 77 StringDecoder.prototype.write = function write(buf) { 78 if (typeof buf === 'string') 79 return buf; 80 if (!ArrayBufferIsView(buf)) 81 throw new ERR_INVALID_ARG_TYPE('buf', 82 ['Buffer', 'TypedArray', 'DataView'], 83 buf); 84 return decode(this[kNativeDecoder], buf); 85 }; 86 87 StringDecoder.prototype.end = function end(buf) { 88 let ret = ''; 89 if (buf !== undefined) 90 ret = this.write(buf); 91 if (this[kNativeDecoder][kBufferedBytes] > 0) 92 ret += flush(this[kNativeDecoder]); 93 return ret; 94 }; 95 96 /* Everything below this line is undocumented legacy stuff. */ 97 StringDecoder.prototype.text = function text(buf, offset) { 98 this[kNativeDecoder][kMissingBytes] = 0; 99 this[kNativeDecoder][kBufferedBytes] = 0; 100 return this.write(buf.slice(offset)); 101 }; 102 103 ObjectDefineProperties(StringDecoder.prototype, { 104 lastChar: { 105 configurable: true, 106 enumerable: true, 107 get() { 108 return TypedArrayPrototypeSubarray(this[kNativeDecoder], 109 kIncompleteCharactersStart, 110 kIncompleteCharactersEnd); 111 } 112 }, 113 lastNeed: { 114 configurable: true, 115 enumerable: true, 116 get() { 117 return this[kNativeDecoder][kMissingBytes]; 118 } 119 }, 120 lastTotal: { 121 configurable: true, 122 enumerable: true, 123 get() { 124 return this[kNativeDecoder][kBufferedBytes] + 125 this[kNativeDecoder][kMissingBytes]; 126 } 127 } 128 }); 129 130 exports.StringDecoder = StringDecoder; 131