1 /* 2 * Copyright (C) 2013 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: 7 * 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above 11 * copyright notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * * Neither the name of Google Inc. nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #ifndef ArrayBufferBuilder_h 32 #define ArrayBufferBuilder_h 33 34 #include "wtf/ArrayBuffer.h" 35 #include "wtf/Noncopyable.h" 36 #include "wtf/RefPtr.h" 37 #include "wtf/text/WTFString.h" 38 39 namespace WTF { 40 41 // A utility class to build an ArrayBuffer instance. Validity must be checked 42 // by isValid() before using an instance. 43 class WTF_EXPORT ArrayBufferBuilder { 44 // Disallow copying since it's expensive and we don't want code to do it by 45 // accident. 46 WTF_MAKE_NONCOPYABLE(ArrayBufferBuilder); 47 48 public: 49 // Creates an ArrayBufferBuilder using the default capacity. 50 ArrayBufferBuilder(); 51 ArrayBufferBuilder(unsigned capacity)52 ArrayBufferBuilder(unsigned capacity) 53 : m_bytesUsed(0) 54 , m_variableCapacity(true) 55 { 56 m_buffer = ArrayBuffer::create(capacity, 1); 57 } 58 isValid()59 bool isValid() const 60 { 61 return m_buffer; 62 } 63 64 // Appending empty data is not allowed. 65 unsigned append(const char* data, unsigned length); 66 67 // Returns the accumulated data as an ArrayBuffer instance. If needed, 68 // creates a new ArrayBuffer instance and copies contents from the internal 69 // buffer to it. Otherwise, returns a PassRefPtr pointing to the internal 70 // buffer. 71 PassRefPtr<ArrayBuffer> toArrayBuffer(); 72 73 // Converts the accumulated data into a String using the default encoding. 74 String toString(); 75 76 // Number of bytes currently accumulated. byteLength()77 unsigned byteLength() const 78 { 79 return m_bytesUsed; 80 } 81 82 // Number of bytes allocated. capacity()83 unsigned capacity() const 84 { 85 return m_buffer->byteLength(); 86 } 87 88 void shrinkToFit(); 89 data()90 const void* data() const 91 { 92 return m_buffer->data(); 93 } 94 95 // If set to false, the capacity won't be expanded and when appended data 96 // overflows, the overflowed part will be dropped. setVariableCapacity(bool value)97 void setVariableCapacity(bool value) 98 { 99 m_variableCapacity = value; 100 } 101 102 private: 103 // Expands the size of m_buffer to size + m_bytesUsed bytes. Returns true 104 // iff successful. If reallocation is needed, copies only data in 105 // [0, m_bytesUsed) range. 106 bool expandCapacity(unsigned size); 107 108 unsigned m_bytesUsed; 109 bool m_variableCapacity; 110 RefPtr<ArrayBuffer> m_buffer; 111 }; 112 113 } // namespace WTF 114 115 using WTF::ArrayBufferBuilder; 116 117 #endif // ArrayBufferBuilder_h 118