1    :  // Copyright 2012 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    :  #ifndef SYZYGY_COMMON_COMPARABLE_H_
  16    :  #define SYZYGY_COMMON_COMPARABLE_H_
  17    :  
  18    :  namespace common {
  19    :  
  20    :  // A 'mixin' class for endowing any class with comparison operators,
  21    :  // provided it implements a 3-way compare function with signature
  22    :  // 'int Compare(const T& other) const;'.
  23    :  template<typename T> class Comparable {
  24    :   public:
  25  E :    bool operator==(const T& other) const {
  26  E :      return reinterpret_cast<const T*>(this)->Compare(other) == 0;
  27  E :    }
  28    :  
  29  E :    bool operator!=(const T& other) const {
  30  E :      return reinterpret_cast<const T*>(this)->Compare(other) != 0;
  31  E :    }
  32    :  
  33  E :    bool operator<=(const T& other) const {
  34  E :      return reinterpret_cast<const T*>(this)->Compare(other) <= 0;
  35  E :    }
  36    :  
  37  E :    bool operator<(const T& other) const {
  38  E :      return reinterpret_cast<const T*>(this)->Compare(other) < 0;
  39  E :    }
  40    :  
  41  E :    bool operator>=(const T& other) const {
  42  E :      return reinterpret_cast<const T*>(this)->Compare(other) >= 0;
  43  E :    }
  44    :  
  45  E :    bool operator>(const T& other) const {
  46  E :      return reinterpret_cast<const T*>(this)->Compare(other) > 0;
  47  E :    }
  48    :  };
  49    :  
  50    :  }  // namespace common
  51    :  
  52    :  #endif  // SYZYGY_COMMON_COMPARABLE_H_