gecko-dev/xpcom/ds/nsDataHashtable.h

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C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsDataHashtable_h__
#define nsDataHashtable_h__
#include "nsHashKeys.h"
#include "nsBaseHashtable.h"
#include "mozilla/Maybe.h"
/**
* templated hashtable class maps keys to simple datatypes.
* See nsBaseHashtable for complete declaration
* @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
* for a complete specification.
* @param DataType the simple datatype being wrapped
* @see nsInterfaceHashtable, nsClassHashtable
*/
template <class KeyClass, class DataType>
class nsDataHashtable : public nsBaseHashtable<KeyClass, DataType, DataType> {
private:
typedef nsBaseHashtable<KeyClass, DataType, DataType> BaseClass;
public:
using typename BaseClass::EntryType;
using typename BaseClass::KeyType;
nsDataHashtable() = default;
explicit nsDataHashtable(uint32_t aInitLength) : BaseClass(aInitLength) {}
/**
* Retrieve a reference to the value for a key.
*
* @param aKey the key to retrieve.
* @return a reference to the found value, or nullptr if no entry was found
* with the given key.
*/
DataType* GetValue(KeyType aKey) {
if (EntryType* ent = this->GetEntry(aKey)) {
return ent->GetModifiableData();
}
return nullptr;
}
/**
* Retrieve the value for a key and remove the corresponding entry at
* the same time.
*
* @param aKey the key to retrieve and remove
* @return the found value, or Nothing if no entry was found with the
* given key.
*/
mozilla::Maybe<DataType> GetAndRemove(KeyType aKey) {
mozilla::Maybe<DataType> value;
if (EntryType* ent = this->GetEntry(aKey)) {
value.emplace(std::move(*ent->GetModifiableData()));
this->RemoveEntry(ent);
}
return value;
}
};
#endif // nsDataHashtable_h__