Home | History | Annotate | Download | only in util 
      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef AAPT_UTIL_IMMUTABLEMAP_H
     18 #define AAPT_UTIL_IMMUTABLEMAP_H
     19 
     20 #include "util/TypeTraits.h"
     21 
     22 #include <utility>
     23 #include <vector>
     24 
     25 namespace aapt {
     26 
     27 template <typename TKey, typename TValue>
     28 class ImmutableMap {
     29     static_assert(is_comparable<TKey, TKey>::value, "key is not comparable");
     30 
     31 private:
     32     std::vector<std::pair<TKey, TValue>> mData;
     33 
     34     explicit ImmutableMap(std::vector<std::pair<TKey, TValue>> data) : mData(std::move(data)) {
     35     }
     36 
     37 public:
     38     using const_iterator = typename decltype(mData)::const_iterator;
     39 
     40     ImmutableMap(ImmutableMap&&) = default;
     41     ImmutableMap& operator=(ImmutableMap&&) = default;
     42 
     43     ImmutableMap(const ImmutableMap&) = delete;
     44     ImmutableMap& operator=(const ImmutableMap&) = delete;
     45 
     46     static ImmutableMap<TKey, TValue> createPreSorted(
     47             std::initializer_list<std::pair<TKey, TValue>> list) {
     48         return ImmutableMap(std::vector<std::pair<TKey, TValue>>(list.begin(), list.end()));
     49     }
     50 
     51     static ImmutableMap<TKey, TValue> createAndSort(
     52             std::initializer_list<std::pair<TKey, TValue>> list) {
     53         std::vector<std::pair<TKey, TValue>> data(list.begin(), list.end());
     54         std::sort(data.begin(), data.end());
     55         return ImmutableMap(std::move(data));
     56     }
     57 
     58     template <typename TKey2,
     59               typename = typename std::enable_if<is_comparable<TKey, TKey2>::value>::type>
     60     const_iterator find(const TKey2& key) const {
     61         auto cmp = [](const std::pair<TKey, TValue>& candidate, const TKey2& target) -> bool {
     62             return candidate.first < target;
     63         };
     64 
     65         const_iterator endIter = end();
     66         auto iter = std::lower_bound(mData.begin(), endIter, key, cmp);
     67         if (iter == endIter || iter->first == key) {
     68             return iter;
     69         }
     70         return endIter;
     71     }
     72 
     73     const_iterator begin() const {
     74         return mData.begin();
     75     }
     76 
     77     const_iterator end() const {
     78         return mData.end();
     79     }
     80 };
     81 
     82 } // namespace aapt
     83 
     84 #endif /* AAPT_UTIL_IMMUTABLEMAP_H */
     85