text: // Copyright (c) 2014-2018, The Monero Project
  // 
  // All rights reserved.
  // 
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  // 
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  // 
  // 2. 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.
  // 
  // 3. Neither the name of the copyright holder 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 HOLDER 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.
  
  #pragma once
  
  // the loose definitions of types in this file are, well, loose.
  //
  // these helpers aren't here for absolute type certainty at compile-time,
  // but rather to help with templated functions telling types apart.
  
  namespace sfinae
  {
  
    typedef char true_type;
  
    struct false_type { true_type a[2]; };
  
    template <typename T>
    struct is_not_container
    {
    private:
  
      // does not have const iterator
      template <typename C> static false_type c_iter(typename C::const_iterator*);
      template <typename C> static true_type c_iter(...);
  
      // does not have value_type
      template <typename C> static false_type v_type(typename C::value_type*);
      template <typename C> static true_type v_type(...);
  
      // does not have key_type
      template <typename C> static false_type k_type(typename C::key_type*);
      template <typename C> static true_type k_type(...);
  
      // does not have mapped_type
      template <typename C> static false_type m_type(typename C::mapped_type*);
      template <typename C> static true_type m_type(...);
  
    public:
  
      static const bool value = (
        (
          sizeof(c_iter<T>(0)) == sizeof(true_type) &&
          sizeof(v_type<T>(0)) == sizeof(true_type) &&
          sizeof(k_type<T>(0)) == sizeof(true_type) &&
          sizeof(m_type<T>(0)) == sizeof(true_type)
        )
        || std::is_same<T, std::string>::value
      );
  
      typedef T type;
    };
  
    template <typename T>
    struct is_vector_like
    {
    private:
  
      // has const iterator
      template <typename C> static true_type c_iter(typename C::const_iterator*);
      template <typename C> static false_type c_iter(...);
  
      // has value_type
      template <typename C> static true_type v_type(typename C::value_type*);
      template <typename C> static false_type v_type(...);
  
      // does not have key_type
      template <typename C> static false_type k_type(typename C::key_type*);
      template <typename C> static true_type k_type(...);
  
      // does not have mapped_type
      template <typename C> static false_type m_type(typename C::mapped_type*);
      template <typename C> static true_type m_type(...);
  
    public:
  
      static const bool value = (
          sizeof(c_iter<T>(0)) == sizeof(true_type) &&
          sizeof(v_type<T>(0)) == sizeof(true_type) &&
          sizeof(k_type<T>(0)) == sizeof(true_type) &&
          sizeof(m_type<T>(0)) == sizeof(true_type) &&
          !std::is_same<T, std::string>::value
      );
  
      typedef T type;
    };
  
    template <typename T>
    struct is_map_like
    {
    private:
  
      // has const iterator
      template <typename C> static true_type c_iter(typename C::const_iterator*);
      template <typename C> static false_type c_iter(...);
  
      // has value_type
      template <typename C> static true_type v_type(typename C::value_type*);
      template <typename C> static false_type v_type(...);
  
      // has key_type
      template <typename C> static true_type k_type(typename C::key_type*);
      template <typename C> static false_type k_type(...);
  
      // has mapped_type
      template <typename C> static true_type m_type(typename C::mapped_type*);
      template <typename C> static false_type m_type(...);
  
    public:
  
      static const bool value = (
          sizeof(c_iter<T>(0)) == sizeof(true_type) &&
          sizeof(v_type<T>(0)) == sizeof(true_type) &&
          sizeof(k_type<T>(0)) == sizeof(true_type) &&
          sizeof(m_type<T>(0)) == sizeof(true_type) &&
          !std::is_same<T, std::string>::value
      );
  
      typedef T type;
    };
  
  }  // namespace sfinae
  