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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/Bag.h>
#include <wtf/HashMap.h>
#include <wtf/Noncopyable.h>
#include <wtf/SentinelLinkedList.h>
namespace WTF {
// This is a collection that is meant to be used for building up lists in a certain order. It's
// not an efficient data structure for storing lists, but if you need to build a list by doing
// operations like insertBefore(existingValue, newValue), then this class is a good intermediate
// helper. Note that the type it operates on must be usable as a UncheckedKeyHashMap key.
template<typename T>
class OrderMaker {
WTF_MAKE_FAST_ALLOCATED;
WTF_MAKE_NONCOPYABLE(OrderMaker);
struct Node : BasicRawSentinelNode<Node> {
Node(SentinelTag)
{
}
Node()
{
}
T payload { };
};
public:
OrderMaker()
{
}
void prepend(T value)
{
m_list.push(newNode(value));
}
void append(T value)
{
m_list.append(newNode(value));
}
void insertBefore(T existingValue, T newValue)
{
Node* node = m_map.get(existingValue);
ASSERT(node);
node->prepend(newNode(newValue));
}
void insertAfter(T existingValue, T newValue)
{
Node* node = m_map.get(existingValue);
ASSERT(node);
node->append(newNode(newValue));
}
class iterator {
public:
iterator()
{
}
iterator(typename SentinelLinkedList<Node>::iterator iter)
: m_iter(iter)
{
}
const T& operator*()
{
return m_iter->payload;
}
iterator& operator++()
{
++m_iter;
return *this;
}
friend bool operator==(const iterator&, const iterator&) = default;
private:
typename SentinelLinkedList<Node>::iterator m_iter;
};
iterator begin() const { return iterator(const_cast<SentinelLinkedList<Node>&>(m_list).begin()); }
iterator end() const { return iterator(const_cast<SentinelLinkedList<Node>&>(m_list).end()); }
private:
Node* newNode(T value)
{
Node* result = m_nodes.add();
result->payload = value;
m_map.set(value, result);
return result;
}
UncheckedKeyHashMap<T, Node*> m_map;
Bag<Node> m_nodes; // FIXME: We could just manually free the contents of the linked list.
SentinelLinkedList<Node> m_list;
};
} // namespace WTF
using WTF::OrderMaker;
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