Source/WTF/wtf/IndexMap.h

/*
 * Copyright (C) 2015-2017 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. ``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
 * 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/IndexKeyType.h>
#include <wtf/Vector.h>

namespace WTF {

// This is a map for keys that have an index(). It's super efficient for BasicBlocks. It's only
// efficient for Values if you don't create too many of these maps, since Values can have very
// sparse indices and there are a lot of Values.

template<typename Key, typename Value>
class IndexMap {
    WTF_MAKE_FAST_ALLOCATED;
public:
    IndexMap() = default;
    IndexMap(IndexMap&&) = default;
    IndexMap& operator=(IndexMap&&) = default;
    IndexMap(const IndexMap&) = default;
    IndexMap& operator=(const IndexMap&) = default;
    
    template<typename... Args>
    explicit IndexMap(size_t size, Args&&... args)
    {
        m_vector.fill(Value(std::forward<Args>(args)...), size);
    }

    template<typename... Args>
    void resize(size_t size, Args&&... args)
    {
        m_vector.fill(Value(std::forward<Args>(args)...), size);
    }

    template<typename... Args>
    void clear(Args&&... args)
    {
        m_vector.fill(Value(std::forward<Args>(args)...), m_vector.size());
    }

    size_t size() const { return m_vector.size(); }

    Value& at(const Key& key)
    {
        return m_vector[IndexKeyType<Key>::index(key)];
    }
    
    const Value& at(const Key& key) const
    {
        return m_vector[IndexKeyType<Key>::index(key)];
    }

    Value& at(size_t index)
    {
        return m_vector[index];
    }

    const Value& at(size_t index) const
    {
        return m_vector[index];
    }
    
    Value& operator[](size_t index) { return at(index); }
    const Value& operator[](size_t index) const { return at(index); }
    Value& operator[](const Key& key) { return at(key); }
    const Value& operator[](const Key& key) const { return at(key); }
    
    template<typename PassedValue>
    void append(const Key& key, PassedValue&& value)
    {
        RELEASE_ASSERT(IndexKeyType<Key>::index(key) == m_vector.size());
        m_vector.append(std::forward<PassedValue>(value));
    }

private:
    Vector<Value, 0, UnsafeVectorOverflow> m_vector;
};

} // namespace WTF

using WTF::IndexMap;