1 // Copyright 2018 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef NET_TOOLS_HUFFMAN_TRIE_TRIE_TRIE_WRITER_H_
6 #define NET_TOOLS_HUFFMAN_TRIE_TRIE_TRIE_WRITER_H_
7 
8 #include <string>
9 #include <vector>
10 
11 #include "net/tools/huffman_trie/bit_writer.h"
12 #include "net/tools/huffman_trie/huffman/huffman_builder.h"
13 #include "net/tools/huffman_trie/trie_entry.h"
14 
15 namespace net {
16 
17 namespace huffman_trie {
18 
19 enum : uint8_t { kTerminalValue = 0, kEndOfTableValue = 127 };
20 
21 class TrieWriter {
22  public:
23   TrieWriter(const HuffmanRepresentationTable& huffman_table,
24              HuffmanBuilder* huffman_builder);
25   ~TrieWriter();
26 
27   // Constructs a trie containing all |entries|. The output is written to
28   // |buffer_| and |*position| is set to the position of the trie root. Returns
29   // true on success and false on failure.
30   bool WriteEntries(const TrieEntries& entries, uint32_t* position);
31 
32   // Returns the position |buffer_| is currently at. The returned value
33   // represents the number of bits.
34   uint32_t position() const;
35 
36   // Flushes |buffer_|.
37   void Flush();
38 
39   // Returns the trie bytes. Call Flush() first to ensure the buffer is
40   // complete.
bytes()41   const std::vector<uint8_t>& bytes() const { return buffer_.bytes(); }
42 
43  protected:
huffman_table()44   const HuffmanRepresentationTable& huffman_table() const {
45     return huffman_table_;
46   }
47 
huffman_builder()48   HuffmanBuilder* huffman_builder() { return huffman_builder_; }
49 
50  private:
51   bool WriteDispatchTables(ReversedEntries::iterator start,
52                            ReversedEntries::iterator end,
53                            uint32_t* position);
54 
55   BitWriter buffer_;
56   const HuffmanRepresentationTable& huffman_table_;
57   HuffmanBuilder* huffman_builder_;
58 };
59 
60 }  // namespace huffman_trie
61 
62 }  // namespace net
63 
64 #endif  // NET_TOOLS_HUFFMAN_TRIE_TRIE_TRIE_WRITER_H_
65