57 lines
2.5 KiB
C++
57 lines
2.5 KiB
C++
// Copyright (c) 2016 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_INDIRECTMAP_H
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#define BITCOIN_INDIRECTMAP_H
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template <class T>
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struct DereferencingComparator { bool operator()(const T a, const T b) const { return *a < *b; } };
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/* Map whose keys are pointers, but are compared by their dereferenced values.
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*
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* Differs from a plain std::map<const K*, T, DereferencingComparator<K*> > in
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* that methods that take a key for comparison take a K rather than taking a K*
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* (taking a K* would be confusing, since it's the value rather than the address
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* of the object for comparison that matters due to the dereferencing comparator).
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*
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* Objects pointed to by keys must not be modified in any way that changes the
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* result of DereferencingComparator.
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*/
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template <class K, class T>
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class indirectmap {
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private:
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typedef std::map<const K*, T, DereferencingComparator<const K*> > base;
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base m;
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public:
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typedef typename base::iterator iterator;
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typedef typename base::const_iterator const_iterator;
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typedef typename base::size_type size_type;
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typedef typename base::value_type value_type;
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// passthrough (pointer interface)
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std::pair<iterator, bool> insert(const value_type& value) { return m.insert(value); }
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// pass address (value interface)
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iterator find(const K& key) { return m.find(&key); }
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const_iterator find(const K& key) const { return m.find(&key); }
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iterator lower_bound(const K& key) { return m.lower_bound(&key); }
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const_iterator lower_bound(const K& key) const { return m.lower_bound(&key); }
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size_type erase(const K& key) { return m.erase(&key); }
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size_type count(const K& key) const { return m.count(&key); }
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// passthrough
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bool empty() const { return m.empty(); }
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size_type size() const { return m.size(); }
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size_type max_size() const { return m.max_size(); }
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void clear() { m.clear(); }
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iterator begin() { return m.begin(); }
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iterator end() { return m.end(); }
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const_iterator begin() const { return m.begin(); }
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const_iterator end() const { return m.end(); }
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const_iterator cbegin() const { return m.cbegin(); }
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const_iterator cend() const { return m.cend(); }
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};
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#endif // BITCOIN_INDIRECTMAP_H
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