| // Copyright 2010-2015, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "storage/louds/bit_vector_based_array_builder.h" |
| |
| #include "base/logging.h" |
| #include "storage/louds/bit_stream.h" |
| |
| namespace mozc { |
| namespace storage { |
| namespace louds { |
| |
| // Initial values of base_length_ and step_length_ is (4, 1) bytes. |
| BitVectorBasedArrayBuilder::BitVectorBasedArrayBuilder() |
| : built_(false), base_length_(4), step_length_(1) { |
| } |
| |
| BitVectorBasedArrayBuilder::~BitVectorBasedArrayBuilder() { |
| } |
| |
| void BitVectorBasedArrayBuilder::Add(const string &element) { |
| CHECK(!built_); |
| elements_.push_back(element); |
| } |
| |
| void BitVectorBasedArrayBuilder::SetSize( |
| size_t base_length, size_t step_length) { |
| CHECK(!built_); |
| base_length_ = base_length; |
| step_length_ = step_length; |
| } |
| |
| namespace { |
| void PushInt32(int value, string *image) { |
| CHECK_EQ(value & ~0xFFFFFFFF, 0); |
| |
| // Output from LSB to MSB. |
| image->push_back(static_cast<char>(value & 0xFF)); |
| image->push_back(static_cast<char>((value >> 8) & 0xFF)); |
| image->push_back(static_cast<char>((value >> 16) & 0xFF)); |
| image->push_back(static_cast<char>((value >> 24) & 0xFF)); |
| } |
| } // namespace |
| |
| void BitVectorBasedArrayBuilder::Build() { |
| CHECK(!built_); |
| |
| BitStream bit_stream; |
| string data; |
| |
| // Output to the bit_stream and the data. |
| for (size_t i = 0; i < elements_.size(); ++i) { |
| const string &element = elements_[i]; |
| |
| // Counts how many steps is needed. |
| int num_steps = 0; |
| for (size_t length = element.length(); length > base_length_; |
| length -= step_length_) { |
| ++num_steps; |
| } |
| |
| // Output '0' as a beginning bit, followed by the num_steps of '1'-bits. |
| size_t output_length = base_length_ + num_steps * step_length_; |
| DCHECK_GE(output_length, element.length()); |
| bit_stream.PushBit(0); |
| for (int j = 0; j < num_steps; ++j) { |
| bit_stream.PushBit(1); |
| } |
| |
| // Output word data (excluding '\0' termination) and then padding by '\0' |
| // to align to the output length. |
| data.append(element); |
| data.append(output_length - element.length(), '\0'); |
| } |
| |
| // Output a sentinel, and align to 32 bits. |
| bit_stream.PushBit(0); |
| bit_stream.FillPadding32(); |
| |
| // Output the image. |
| PushInt32(bit_stream.ByteSize(), &image_); |
| PushInt32(base_length_, &image_); |
| PushInt32(step_length_, &image_); |
| PushInt32(0, &image_); |
| |
| image_.append(bit_stream.image()); |
| image_.append(data); |
| |
| built_ = true; |
| } |
| |
| const string &BitVectorBasedArrayBuilder::image() const { |
| CHECK(built_); |
| return image_; |
| } |
| |
| } // namespace louds |
| } // namespace storage |
| } // namespace mozc |