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// Copyright (c) 2016 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
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