Line data    Source code

       1             : // Copyright (c) 2016-2020 The Bitcoin Core developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : #ifndef BITCOIN_INDIRECTMAP_H
       6             : #define BITCOIN_INDIRECTMAP_H
       7             : 
       8             : #include <map>
       9             : 
      10             : template <class T>
      11      309793 : struct DereferencingComparator { bool operator()(const T a, const T b) const { return *a < *b; } };
      12             : 
      13             : /* Map whose keys are pointers, but are compared by their dereferenced values.
      14             :  *
      15             :  * Differs from a plain std::map<const K*, T, DereferencingComparator<K*> > in
      16             :  * that methods that take a key for comparison take a K rather than taking a K*
      17             :  * (taking a K* would be confusing, since it's the value rather than the address
      18             :  * of the object for comparison that matters due to the dereferencing comparator).
      19             :  *
      20             :  * Objects pointed to by keys must not be modified in any way that changes the
      21             :  * result of DereferencingComparator.
      22             :  */
      23             : template <class K, class T>
      24             : class indirectmap {
      25             : private:
      26             :     typedef std::map<const K*, T, DereferencingComparator<const K*> > base;
      27             :     base m;
      28             : public:
      29             :     typedef typename base::iterator iterator;
      30             :     typedef typename base::const_iterator const_iterator;
      31             :     typedef typename base::size_type size_type;
      32             :     typedef typename base::value_type value_type;
      33             : 
      34             :     // passthrough (pointer interface)
      35        4805 :     std::pair<iterator, bool> insert(const value_type& value) { return m.insert(value); }
      36             : 
      37             :     // pass address (value interface)
      38         201 :     iterator find(const K& key)                     { return m.find(&key); }
      39      253072 :     const_iterator find(const K& key) const         { return m.find(&key); }
      40           0 :     iterator lower_bound(const K& key)              { return m.lower_bound(&key); }
      41        2005 :     const_iterator lower_bound(const K& key) const  { return m.lower_bound(&key); }
      42        4633 :     size_type erase(const K& key)                   { return m.erase(&key); }
      43           0 :     size_type count(const K& key) const             { return m.count(&key); }
      44             : 
      45             :     // passthrough
      46             :     bool empty() const              { return m.empty(); }
      47       18489 :     size_type size() const          { return m.size(); }
      48             :     size_type max_size() const      { return m.max_size(); }
      49             :     void clear()                    { m.clear(); }
      50             :     iterator begin()                { return m.begin(); }
      51         201 :     iterator end()                  { return m.end(); }
      52             :     const_iterator begin() const    { return m.begin(); }
      53      255720 :     const_iterator end() const      { return m.end(); }
      54        6628 :     const_iterator cbegin() const   { return m.cbegin(); }
      55       10937 :     const_iterator cend() const     { return m.cend(); }
      56             : };
      57             : 
      58             : #endif // BITCOIN_INDIRECTMAP_H