Zoltan Szabadka | e765008 | 2014-03-20 14:32:35 +0100 | [diff] [blame^] | 1 | // Copyright 2013 Google Inc. All Rights Reserved. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | // |
| 15 | // Class to model the static dictionary. |
| 16 | |
| 17 | #ifndef BROTLI_ENC_STATIC_DICT_H_ |
| 18 | #define BROTLI_ENC_STATIC_DICT_H_ |
| 19 | |
| 20 | #include <algorithm> |
| 21 | #include <unordered_map> |
| 22 | #include <string> |
| 23 | |
| 24 | namespace brotli { |
| 25 | |
| 26 | class StaticDictionary { |
| 27 | public: |
| 28 | StaticDictionary() {} |
| 29 | void Insert(const std::string &str, int len, int dist) { |
| 30 | int ix = (dist << 6) + len; |
| 31 | std::unordered_map<std::string, int>::const_iterator it = map_.find(str); |
| 32 | if (it != map_.end() && ix >= it->second) { |
| 33 | return; |
| 34 | } |
| 35 | map_[str] = ix; |
| 36 | int v = 0; |
| 37 | for (int i = 0; i < 4 && i < str.size(); ++i) { |
| 38 | v += str[i] << (8 * i); |
| 39 | } |
| 40 | if (prefix_map_[v] < str.size()) { |
| 41 | prefix_map_[v] = str.size(); |
| 42 | } |
| 43 | } |
| 44 | int GetLength(int v) const { |
| 45 | std::unordered_map<int, int>::const_iterator it = prefix_map_.find(v); |
| 46 | if (it == prefix_map_.end()) { |
| 47 | return 0; |
| 48 | } |
| 49 | return it->second; |
| 50 | } |
| 51 | bool Get(const std::string &str, int *len, int *dist) const { |
| 52 | std::unordered_map<std::string, int>::const_iterator it = map_.find(str); |
| 53 | if (it == map_.end()) { |
| 54 | return false; |
| 55 | } |
| 56 | int v = it->second; |
| 57 | *len = v & 63; |
| 58 | *dist = v >> 6; |
| 59 | return true; |
| 60 | } |
| 61 | private: |
| 62 | std::unordered_map<std::string, int> map_; |
| 63 | std::unordered_map<int, int> prefix_map_; |
| 64 | }; |
| 65 | |
| 66 | } // namespace brotli |
| 67 | |
| 68 | #endif // BROTLI_ENC_STATIC_DICT_H_ |