/*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
*
*/
-#ifndef FOLLY_ATOMICHASHMAP_H_
+#pragma once
#define FOLLY_ATOMICHASHMAP_H_
#include <boost/iterator/iterator_facade.hpp>
{}
};
-template<class KeyT, class ValueT,
- class HashFcn, class EqualFcn, class Allocator, class ProbeFcn>
+template<class KeyT, class ValueT, class HashFcn, class EqualFcn,
+ class Allocator, class ProbeFcn, class KeyConvertFcn>
class AtomicHashMap : boost::noncopyable {
-typedef AtomicHashArray<KeyT, ValueT, HashFcn, EqualFcn, Allocator, ProbeFcn>
+typedef AtomicHashArray<KeyT, ValueT, HashFcn, EqualFcn,
+ Allocator, ProbeFcn, KeyConvertFcn>
SubMap;
public:
typedef std::pair<const KeyT, ValueT> value_type;
typedef HashFcn hasher;
typedef EqualFcn key_equal;
+ typedef KeyConvertFcn key_convert;
typedef value_type* pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
*
* Same contract as insert(), but performs in-place construction
* of the value type using the specified arguments.
+ *
+ * Also, like find(), this method optionally allows 'key_in' to have a type
+ * different from that stored in the table; see find(). If and only if no
+ * equal key is already present, this method converts 'key_in' to a key of
+ * type KeyT using the provided LookupKeyToKeyFcn.
*/
- template <typename... ArgTs>
- std::pair<iterator,bool> emplace(key_type k, ArgTs&&... vCtorArg);
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal,
+ typename LookupKeyToKeyFcn = key_convert,
+ typename... ArgTs>
+ std::pair<iterator,bool> emplace(LookupKeyT k, ArgTs&&... vCtorArg);
/*
* find --
*
- * Returns an iterator into the map.
+ * Returns the iterator to the element if found, otherwise end().
+ *
+ * As an optional feature, the type of the key to look up (LookupKeyT) is
+ * allowed to be different from the type of keys actually stored (KeyT).
*
- * If the key is not found, returns end().
+ * This enables use cases where materializing the key is costly and usually
+ * redudant, e.g., canonicalizing/interning a set of strings and being able
+ * to look up by StringPiece. To use this feature, LookupHashFcn must take
+ * a LookupKeyT, and LookupEqualFcn must take KeyT and LookupKeyT as first
+ * and second parameter, respectively.
+ *
+ * See folly/test/ArrayHashMapTest.cpp for sample usage.
*/
- iterator find(key_type k);
- const_iterator find(key_type k) const;
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ iterator find(LookupKeyT k);
+
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ const_iterator find(LookupKeyT k) const;
/*
* erase --
SimpleRetT() = default;
};
- template <typename... ArgTs>
- SimpleRetT insertInternal(KeyT key, ArgTs&&... value);
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal,
+ typename LookupKeyToKeyFcn = key_convert,
+ typename... ArgTs>
+ SimpleRetT insertInternal(LookupKeyT key, ArgTs&&... value);
- SimpleRetT findInternal(const KeyT k) const;
+ template <typename LookupKeyT = key_type,
+ typename LookupHashFcn = hasher,
+ typename LookupEqualFcn = key_equal>
+ SimpleRetT findInternal(const LookupKeyT k) const;
SimpleRetT findAtInternal(uint32_t idx) const;
} // namespace folly
#include <folly/AtomicHashMap-inl.h>
-
-#endif // FOLLY_ATOMICHASHMAP_H_