| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| part of dart.io; |
| |
| /** |
| * Utility class that can fast concatenate [List<int>]s of bytes. Use |
| * [readBytes] to get the final buffer. |
| */ |
| class _BufferList { |
| const int _INIT_SIZE = 1 * 1024; |
| |
| _BufferList() { |
| clear(); |
| } |
| |
| int pow2roundup(int x) { |
| --x; |
| x |= x >> 1; |
| x |= x >> 2; |
| x |= x >> 4; |
| x |= x >> 8; |
| x |= x >> 16; |
| return x + 1; |
| } |
| |
| /** |
| * Adds a new buffer to the list. |
| */ |
| void add(List<int> buffer) { |
| int bufferLength = buffer.length; |
| int required = _length + bufferLength; |
| if (_buffer == null) { |
| int size = pow2roundup(required); |
| if (size < _INIT_SIZE) size = _INIT_SIZE; |
| _buffer = new Uint8List(size); |
| } else if (_buffer.length < required) { |
| // This will give is a list in the range of 2-4 times larger than |
| // required. |
| int size = pow2roundup(required) * 2; |
| Uint8List newBuffer = new Uint8List(size); |
| newBuffer.setRange(0, _buffer.length, _buffer); |
| _buffer = newBuffer; |
| } |
| assert(_buffer.length >= required); |
| if (buffer is Uint8List) { |
| _buffer.setRange(_length, required, buffer); |
| } else { |
| for (int i = 0; i < bufferLength; i++) { |
| _buffer[_length + i] = buffer[i]; |
| } |
| } |
| _length = required; |
| } |
| |
| /** |
| * Same as [add]. |
| */ |
| void write(List<int> buffer) { |
| add(buffer); |
| } |
| |
| /** |
| * Read all the bytes from the buffer list. If it's empty, an empty list |
| * is returned. A call to [readBytes] will clear the buffer. |
| */ |
| List<int> readBytes() { |
| if (_buffer == null) return new Uint8List(0); |
| var buffer = new Uint8List.view(_buffer.buffer, 0, _length); |
| clear(); |
| return buffer; |
| } |
| |
| /** |
| * Returns the total number of bytes in the buffer. |
| */ |
| int get length => _length; |
| |
| /** |
| * Returns whether the buffer list is empty. |
| */ |
| bool get isEmpty => _length == 0; |
| |
| /** |
| * Returns whether the buffer list is not empty. |
| */ |
| bool get isNotEmpty => !isEmpty; |
| |
| /** |
| * Clears the content of the buffer list. |
| */ |
| void clear() { |
| _length = 0; |
| _buffer = null; |
| } |
| |
| int _length; // Total number of bytes in the buffer. |
| Uint8List _buffer; // Internal buffer. |
| } |