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| 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 // This is a copy of "dart:io"'s BytesBuilder implementation, from | |
| 6 // sdk/lib/io/bytes_builder.dart. It's copied here to make it available to | |
| 7 // non-"dart:io" applications (issue 18348). | |
| 8 // | |
| 9 // Because it's copied directly, there are no modifications from the original. | |
| 10 // | |
| 11 // This is up-to-date as of sdk revision | |
| 12 // 86227840d75d974feb238f8b3c59c038b99c05cf. | |
| 13 import 'dart:math'; | |
| 14 import 'dart:typed_data'; | |
| 15 | |
| 16 /** | |
| 17 * Builds a list of bytes, allowing bytes and lists of bytes to be added at the | |
| 18 * end. | |
| 19 * | |
| 20 * Used to efficiently collect bytes and lists of bytes. | |
| 21 */ | |
| 22 abstract class BytesBuilder { | |
| 23 /** | |
| 24 * Construct a new empty [BytesBuilder]. | |
| 25 * | |
| 26 * If [copy] is true, the data is always copied when added to the list. If | |
| 27 * it [copy] is false, the data is only copied if needed. That means that if | |
| 28 * the lists are changed after added to the [BytesBuilder], it may effect the | |
| 29 * output. Default is `true`. | |
| 30 */ | |
| 31 factory BytesBuilder({bool copy: true}) { | |
| 32 if (copy) { | |
| 33 return new _CopyingBytesBuilder(); | |
| 34 } else { | |
| 35 return new _BytesBuilder(); | |
| 36 } | |
| 37 } | |
| 38 | |
| 39 /** | |
| 40 * Appends [bytes] to the current contents of the builder. | |
| 41 * | |
| 42 * Each value of [bytes] will be bit-representation truncated to the range | |
| 43 * 0 .. 255. | |
| 44 */ | |
| 45 void add(List<int> bytes); | |
| 46 | |
| 47 /** | |
| 48 * Append [byte] to the current contents of the builder. | |
| 49 * | |
| 50 * The [byte] will be bit-representation truncated to the range 0 .. 255. | |
| 51 */ | |
| 52 void addByte(int byte); | |
| 53 | |
| 54 /** | |
| 55 * Returns the contents of `this` and clears `this`. | |
| 56 * | |
| 57 * The list returned is a view of the the internal buffer, limited to the | |
| 58 * [length]. | |
| 59 */ | |
| 60 List<int> takeBytes(); | |
| 61 | |
| 62 /** | |
| 63 * Returns a copy of the current contents of the builder. | |
| 64 * | |
| 65 * Leaves the contents of the builder intact. | |
| 66 */ | |
| 67 List<int> toBytes(); | |
| 68 | |
| 69 /** | |
| 70 * The number of bytes in the builder. | |
| 71 */ | |
| 72 int get length; | |
| 73 | |
| 74 /** | |
| 75 * Returns `true` if the buffer is empty. | |
| 76 */ | |
| 77 bool get isEmpty; | |
| 78 | |
| 79 /** | |
| 80 * Returns `true` if the buffer is not empty. | |
| 81 */ | |
| 82 bool get isNotEmpty; | |
| 83 | |
| 84 /** | |
| 85 * Clear the contents of the builder. | |
| 86 */ | |
| 87 void clear(); | |
| 88 } | |
| 89 | |
| 90 | |
| 91 class _CopyingBytesBuilder implements BytesBuilder { | |
| 92 // Start with 1024 bytes. | |
| 93 static const int _INIT_SIZE = 1024; | |
| 94 | |
| 95 int _length = 0; | |
| 96 Uint8List _buffer; | |
| 97 | |
| 98 void add(List<int> bytes) { | |
| 99 int bytesLength = bytes.length; | |
| 100 if (bytesLength == 0) return; | |
| 101 int required = _length + bytesLength; | |
| 102 if (_buffer == null) { | |
| 103 int size = _pow2roundup(required); | |
| 104 size = max(size, _INIT_SIZE); | |
| 105 _buffer = new Uint8List(size); | |
| 106 } else if (_buffer.length < required) { | |
| 107 // We will create a list in the range of 2-4 times larger than | |
| 108 // required. | |
| 109 int size = _pow2roundup(required) * 2; | |
| 110 var newBuffer = new Uint8List(size); | |
| 111 newBuffer.setRange(0, _buffer.length, _buffer); | |
| 112 _buffer = newBuffer; | |
| 113 } | |
| 114 assert(_buffer.length >= required); | |
| 115 if (bytes is Uint8List) { | |
| 116 _buffer.setRange(_length, required, bytes); | |
| 117 } else { | |
| 118 for (int i = 0; i < bytesLength; i++) { | |
| 119 _buffer[_length + i] = bytes[i]; | |
| 120 } | |
| 121 } | |
| 122 _length = required; | |
| 123 } | |
| 124 | |
| 125 void addByte(int byte) => add([byte]); | |
| 126 | |
| 127 List<int> takeBytes() { | |
| 128 if (_buffer == null) return new Uint8List(0); | |
| 129 var buffer = new Uint8List.view(_buffer.buffer, 0, _length); | |
| 130 clear(); | |
| 131 return buffer; | |
| 132 } | |
| 133 | |
| 134 List<int> toBytes() { | |
| 135 if (_buffer == null) return new Uint8List(0); | |
| 136 return new Uint8List.fromList( | |
| 137 new Uint8List.view(_buffer.buffer, 0, _length)); | |
| 138 } | |
| 139 | |
| 140 int get length => _length; | |
| 141 | |
| 142 bool get isEmpty => _length == 0; | |
| 143 | |
| 144 bool get isNotEmpty => _length != 0; | |
| 145 | |
| 146 void clear() { | |
| 147 _length = 0; | |
| 148 _buffer = null; | |
| 149 } | |
| 150 | |
| 151 int _pow2roundup(int x) { | |
| 152 --x; | |
| 153 x |= x >> 1; | |
| 154 x |= x >> 2; | |
| 155 x |= x >> 4; | |
| 156 x |= x >> 8; | |
| 157 x |= x >> 16; | |
| 158 return x + 1; | |
| 159 } | |
| 160 } | |
| 161 | |
| 162 | |
| 163 class _BytesBuilder implements BytesBuilder { | |
| 164 int _length = 0; | |
| 165 final List _chunks = []; | |
| 166 | |
| 167 void add(List<int> bytes) { | |
| 168 if (bytes is! Uint8List) { | |
| 169 bytes = new Uint8List.fromList(bytes); | |
| 170 } | |
| 171 _chunks.add(bytes); | |
| 172 _length += bytes.length; | |
| 173 } | |
| 174 | |
| 175 void addByte(int byte) => add([byte]); | |
| 176 | |
| 177 List<int> takeBytes() { | |
| 178 if (_chunks.length == 0) return new Uint8List(0); | |
| 179 if (_chunks.length == 1) { | |
| 180 var buffer = _chunks.single; | |
| 181 clear(); | |
| 182 return buffer; | |
| 183 } | |
| 184 var buffer = new Uint8List(_length); | |
| 185 int offset = 0; | |
| 186 for (var chunk in _chunks) { | |
| 187 buffer.setRange(offset, offset + chunk.length, chunk); | |
| 188 offset += chunk.length; | |
| 189 } | |
| 190 clear(); | |
| 191 return buffer; | |
| 192 } | |
| 193 | |
| 194 List<int> toBytes() { | |
| 195 if (_chunks.length == 0) return new Uint8List(0); | |
| 196 var buffer = new Uint8List(_length); | |
| 197 int offset = 0; | |
| 198 for (var chunk in _chunks) { | |
| 199 buffer.setRange(offset, offset + chunk.length, chunk); | |
| 200 offset += chunk.length; | |
| 201 } | |
| 202 return buffer; | |
| 203 } | |
| 204 | |
| 205 int get length => _length; | |
| 206 | |
| 207 bool get isEmpty => _length == 0; | |
| 208 | |
| 209 bool get isNotEmpty => _length != 0; | |
| 210 | |
| 211 void clear() { | |
| 212 _length = 0; | |
| 213 _chunks.clear(); | |
| 214 } | |
| 215 } | |
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