// Copyright (c) 2016-2020 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_INDIRECTMAP_H

#define BITCOIN_INDIRECTMAP_H

#include <map>

template <class T>

struct DereferencingComparator { bool operator()(const T a, const T b) const { return *a < *b; } };

/* Map whose keys are pointers, but are compared by their dereferenced values.

 *

 * Differs from a plain std::map<const K*, T, DereferencingComparator<K*> > in

 * that methods that take a key for comparison take a K rather than taking a K*

 * (taking a K* would be confusing, since it's the value rather than the address

 * of the object for comparison that matters due to the dereferencing comparator).

 *

 * Objects pointed to by keys must not be modified in any way that changes the

 * result of DereferencingComparator.

 */

template <class K, class T>

class indirectmap {

private:

    typedef std::map<const K*, T, DereferencingComparator<const K*> > base;

    base m;

public:

    typedef typename base::iterator iterator;

    typedef typename base::const_iterator const_iterator;

    typedef typename base::size_type size_type;

    typedef typename base::value_type value_type;

    // passthrough (pointer interface)

    std::pair<iterator, bool> insert(const value_type& value) { return m.insert(value); }

    // pass address (value interface)

    iterator find(const K& key)                     { return m.find(&key); }

    const_iterator find(const K& key) const         { return m.find(&key); }

    iterator lower_bound(const K& key)              { return m.lower_bound(&key); }

    const_iterator lower_bound(const K& key) const  { return m.lower_bound(&key); }

    size_type erase(const K& key)                   { return m.erase(&key); }

    size_type count(const K& key) const             { return m.count(&key); }

    // passthrough

    bool empty() const              { return m.empty(); }

    size_type size() const          { return m.size(); }

    size_type max_size() const      { return m.max_size(); }

    void clear()                    { m.clear(); }

    iterator begin()                { return m.begin(); }

    iterator end()                  { return m.end(); }

    const_iterator begin() const    { return m.begin(); }

    const_iterator end() const      { return m.end(); }

    const_iterator cbegin() const   { return m.cbegin(); }

    const_iterator cend() const     { return m.cend(); }

};

#endif // BITCOIN_INDIRECTMAP_H