linked_map.hxx

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// This file is part of Awali.
// Copyright 2016-2023 Sylvain Lombardy, Victor Marsault, Jacques Sakarovitch
//
// Awali is a free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
 
#ifndef AWALI_LINKED_MAP_HXX
#define AWALI_LINKED_MAP_HXX
 
#include<awali/common/is_iterable.hxx>
 
#include <unordered_map>
#include <list>
#include <stdexcept>
#include <sstream>
 
namespace awali {
 
template <typename K, typename H = std::hash<K>>
class pointed_hash_t : protected H {
public:
  std::size_t operator()(K* key) const noexcept {
    return (key == nullptr) ? 0 : H::operator()(*key);
  }
};
 
template <typename K, typename E = std::equal_to<K>>
class pointed_equal_t : protected E {
public:
  bool operator()(K* key1, K* key2) const noexcept {
    return (key1 == nullptr || key2 == nullptr) ? (key1 == key2) 
                                                : E::operator()(*key1,*key2);
  }
};
 
 
template <typename K, typename V, 
          typename H = std::hash<K>, typename E = std::equal_to<K>>
class linked_map_t {
public:
  typedef linked_map_t<K,V,H,E> self_type_t;
  typedef K key_t;
  typedef V value_t;
  typedef std::pair<key_t const,value_t> pair_t;
  typedef pair_t value_type;
  typedef std::pair<key_t,value_t> init_pair_t;
  typedef std::list<pair_t> list_t;
  typedef typename std::list<pair_t>::iterator iterator;
  typedef typename std::list<pair_t>::const_iterator const_iterator;
  typedef std::unordered_map< key_t const*, 
                              iterator,
                              pointed_hash_t<key_t const,H>,
                              pointed_equal_t<key_t const,E> > map_t;
  typedef typename map_t::size_type size_type;
 
protected:
  map_t map;
  list_t list;
 
  void remap(bool hard) {
    map.clear();
    map.reserve(list.size());
    for(auto it = list.begin(); it != list.end(); it++) {
      if (hard) {
        auto x = map.find(&(it->first));
        if (x != map.end())
          erase(x->second);
      }
      map[&(it->first)]=it;
    }
  }
 
public:
  bool empty() const noexcept { return list.empty(); }
 
  size_type size() const noexcept { return list.size(); }
 
  size_type max_size() const noexcept { return map.max_size(); }
 
  void clear() noexcept { map.clear(); list.clear(); }
 
  size_type bucket_count() const noexcept {return map.bucket_count();}
  size_type bucket_size(unsigned n) const noexcept {return map.bucket_size(n);}
  size_type max_bucket_count() const noexcept {return map.max_bucket_count();}
  float load_factor() const noexcept {return map.load_factor();}
  float max_load_factor() const noexcept {return map.max_load_factor();}
  void max_load_factor(float x) {map.max_load_factor(x);}
  void rehash(size_type n) {map.rehash(n);}
  void reserve(size_type n) {map.reserve(n);}
 
  iterator begin() noexcept {return list.begin();}
  iterator end() noexcept {return list.end();}
 
  const_iterator begin() const noexcept {return cbegin();}
  const_iterator end() const noexcept {return cend();}
 
  const_iterator cbegin() const noexcept {return list.cbegin();}
  const_iterator cend() const noexcept {return list.cend();}
 
 
  iterator
  find(key_t const& key)
  {
    auto res = map.find(&key);
    if (res == map.end())
      return list.end();
    else
      return res->second;
  }
  
  const_iterator
  find(key_t const& key)
  const
  {
    auto res = map.find(&key);
    if (res == map.end())
      return list.cend();
    else
      return res->second;
  }
 
 
  size_type count(key_t const& key) 
  const 
  {
    return map.find(&key) != map.end();
  }
 
 
 
 
 
  iterator insert(const_iterator pos, key_t key, value_t value,
                  bool overwrite_existing = false)
  {
    auto it = map.find(&key);
    if (it != map.end()) {
      if (overwrite_existing) {
        auto list_it = it->second;
        map.erase(it);
        list.erase(list_it);
      }
      else
        return it->second;
    }
    auto res = list.emplace(pos, std::move(key),std::move(value));
    map.emplace(&(res->first),res);
    return res;
  }
 
 
  void push_front(key_t key, value_t value,
                  bool overwrite_existing = false)
  {
    insert(begin(), std::move(key), std::move(value), overwrite_existing);
  }
 
 
  pair_t& front()  { return list.front(); }
  pair_t const& front() const  { return list.front(); }
 
 
  pair_t& back()  { return list.back(); }
  pair_t const& back() const  { return list.back(); }
 
 
  void push_back(key_t key, value_t value, bool overwrite_existing = false)
  {
    insert(end(), std::move(key), std::move(value), overwrite_existing);
  }
 
 
  /* Erases the binding pointed at by given iterator.
   * Does nothing if @pname{pos} is equal to {@link end()}.
   * @return an iterator pointing to the next binding.
   */
  iterator
  erase(const_iterator pos)
  {
    if (pos == this->cend())
      return this->end();
    map.erase(&(pos->first));
    return list.erase(pos);
  }
 
 
  size_type
  erase(key_t const& key)
  {
    auto it = map.find(&key);
    if (it == map.end())
      return 0;
    const_iterator it2 = it->second; // Somehow this is required because 
    map.erase(it);                   // unordered_map tries to hash
    list.erase(it2);                 // its key before erasing from iterator.
    return 1;
  }
 
 
  value_t&
  at (key_t const& key)
  {
    auto it = map.find(&key);
    if (it != map.end())
      return it->second->second;
    std::stringstream ss;
    ss << "This linked_map does not have a binding with key" << key << ".";
    throw std::out_of_range(ss.str());
  }
 
 
  value_t const&
  at (key_t const& key)
  const
  {
    auto it = map.find(&key);
    if (it != map.end())
      return it->second->second;
    std::stringstream ss;
    ss << "This linked_map does not have a binding with key" << key << ".";
    throw std::out_of_range(ss.str());
  }
 
 
 
  value_t&
  operator[] (key_t key)
  {
    auto it = map.find(&key);
    if (it != map.end())
      return it->second->second;
    list.emplace_back(std::move(key),value_t());
    iterator x = --list.end();
    map[&(x->first)] = x;
    return x->second;
  }
 
 
  void
  sort()
  {
    list.sort([](pair_t x,pair_t y){return (x.first < y.first);});
    remap(false);
  }
 
 
  template <class Compare>
  void sort(Compare comp)
  {
    list.sort(comp);
    remap(false);
  }
 
 
  linked_map_t() {}
 
  linked_map_t(std::initializer_list<pair_t> l) : list(std::move(l)) 
  {remap(true);}
  
  linked_map_t(std::list<pair_t> l) : list(std::move(l)) 
  {remap(true);}
 
  linked_map_t(linked_map_t<key_t,value_t> const& other)
  : list(other.list), map() {remap(false);}
 
  linked_map_t(linked_map_t<key_t,value_t>&& other)
  : list(std::move(other.list)), map(std::move(other.map)) {}
                             //  ^^^^^^^^^^^^^^^^^^^^^^^^
                             //  This assumes that the iterators are still valid
                             //  after moving a std::list                   
  
 
  template<class O>
  linked_map_t(
    O&& container,  // /!\ This is a universal reference, not a rvalue reference
    typename std::enable_if<
      is_iterable_with<O,init_pair_t>::value,bool>::type require_remap = true)
  {
    bool b = std::is_lvalue_reference<O>::value; 
    for (auto& pair : container) {
      if (b)                              // This is clearly a case
        list.push_back(pair);             // where C17 `if constexpr` would
      else                                // be beneficial.
        list.push_back(std::move(pair));  //
    }
    remap(require_remap);
  }
  
 
 
  bool operator!=(self_type_t const& other) 
  {return !( (*this) ==  other);}
 
 
  bool operator==(self_type_t const& other) {
    return this->equals_as_list(other);
  }
 
 
  template<typename KeyEquality = E, typename ValueEquality = std::equal_to<V>>
  bool equals_as_list(self_type_t const& other) const
  {
    KeyEquality ke;
    ValueEquality ve;
    const_iterator it1 = begin();
    const_iterator it2 = other.begin();
    while (it1 != end() && it2 != other.end()) {
      if (!ke(it1->first,it2->first))
        return false;
      if (!ve(it1->second,it2->second))
        return false;
      ++it1;
      ++it2;
    }
    return (it1 == end() && it2 == other.end());
  }
 
  template<typename ValueEquality = std::equal_to<V>>
  bool equals_as_map(self_type_t const& other) const
  {
    ValueEquality ve;
    if (this->size() != other.size())
      return false;
    const_iterator end = this->end();
    for(pair_t const& pair: other) {
      const_iterator it = this->find(pair.first);
      if (it == end)
        return false;
      if (!ve(pair.second,it->second))
        return false;
    }
    return true;
  }
};
 
 
 
} // end of namespace awali
 
#endif