Source/WTF/wtf/FixedVector.h

/*
 * Copyright (C) 2021-2022 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
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
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#pragma once

#include <wtf/EmbeddedFixedVector.h>

namespace WTF {

template<typename T>
class FixedVector {
public:
    using Storage = EmbeddedFixedVector<T>;
    using iterator = T*;
    using const_iterator = const T*;
    using reverse_iterator = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;

    FixedVector() = default;
    FixedVector(const FixedVector& other)
        : m_storage(other.m_storage ? other.m_storage->clone().moveToUniquePtr() : nullptr)
    { }
    FixedVector(FixedVector&& other) = default;

    FixedVector(std::initializer_list<T> initializerList)
        : m_storage(initializerList.size() ? Storage::create(initializerList.size()).moveToUniquePtr() : nullptr)
    {
        size_t index = 0;
        for (const auto& element : initializerList) {
            m_storage->at(index) = element;
            index++;
        }
    }

    FixedVector& operator=(const FixedVector& other)
    {
        FixedVector tmp(other);
        swap(tmp);
        return *this;
    }

    FixedVector& operator=(FixedVector&& other)
    {
        FixedVector tmp(WTFMove(other));
        swap(tmp);
        return *this;
    }

    explicit FixedVector(size_t size)
        : m_storage(size ? Storage::create(size).moveToUniquePtr() : nullptr)
    { }

    template<size_t inlineCapacity, typename OverflowHandler>
    explicit FixedVector(const Vector<T, inlineCapacity, OverflowHandler>& other)
        : m_storage(other.isEmpty() ? nullptr : Storage::createFromVector(other).moveToUniquePtr())
    { }

    template<size_t inlineCapacity, typename OverflowHandler>
    FixedVector& operator=(const Vector<T, inlineCapacity, OverflowHandler>& other)
    {
        m_storage = other.isEmpty() ? nullptr : Storage::createFromVector(other).moveToUniquePtr();
        return *this;
    }

    template<size_t inlineCapacity, typename OverflowHandler>
    explicit FixedVector(Vector<T, inlineCapacity, OverflowHandler>&& other)
    {
        Vector<T, inlineCapacity, OverflowHandler> target = WTFMove(other);
        m_storage = target.isEmpty() ? nullptr : Storage::createFromVector(WTFMove(target)).moveToUniquePtr();
    }

    template<size_t inlineCapacity, typename OverflowHandler>
    FixedVector& operator=(Vector<T, inlineCapacity, OverflowHandler>&& other)
    {
        Vector<T, inlineCapacity, OverflowHandler> target = WTFMove(other);
        m_storage = target.isEmpty() ? nullptr : Storage::createFromVector(WTFMove(target)).moveToUniquePtr();
        return *this;
    }

    size_t size() const { return m_storage ? m_storage->size() : 0; }
    bool isEmpty() const { return m_storage ? m_storage->isEmpty() : true; }
    size_t byteSize() const { return m_storage ? m_storage->byteSize() : 0; }

    T* data() { return m_storage ? m_storage->data() : nullptr; }
    iterator begin() { return m_storage ? m_storage->begin() : nullptr; }
    iterator end() { return m_storage ? m_storage->end() : nullptr; }

    const T* data() const { return const_cast<FixedVector*>(this)->data(); }
    const_iterator begin() const { return const_cast<FixedVector*>(this)->begin(); }
    const_iterator end() const { return const_cast<FixedVector*>(this)->end(); }

    reverse_iterator rbegin() { return m_storage ? m_storage->rbegin() : reverse_iterator(nullptr); }
    reverse_iterator rend() { return m_storage ? m_storage->rend() : reverse_iterator(nullptr); }
    const_reverse_iterator rbegin() const { return m_storage ? m_storage->rbegin() : const_reverse_iterator(nullptr); }
    const_reverse_iterator rend() const { return m_storage ? m_storage->rend() : const_reverse_iterator(nullptr); }

    T& at(size_t i) { return m_storage->at(i); }
    const T& at(size_t i) const { return m_storage->at(i); }

    T& operator[](size_t i) { return m_storage->at(i); }
    const T& operator[](size_t i) const { return m_storage->at(i); }

    T& first() { return (*this)[0]; }
    const T& first() const { return (*this)[0]; }
    T& last() { return (*this)[size() - 1]; }
    const T& last() const { return (*this)[size() - 1]; }

    void clear() { m_storage = nullptr; }

    void fill(const T& val)
    {
        if (!m_storage)
            return;
        m_storage->fill(val);
    }

    bool operator!=(const FixedVector<T>& other) const
    {
        return !(*this == other);
    }

    bool operator==(const FixedVector<T>& other) const
    {
        if (!m_storage) {
            if (!other.m_storage)
                return true;
            return other.m_storage->isEmpty();
        }
        if (!other.m_storage)
            return m_storage->isEmpty();
        return *m_storage == *other.m_storage;
    }

    template<typename U> bool contains(const U&) const;
    template<typename U> size_t find(const U&) const;
    template<typename MatchFunction> size_t findIf(const MatchFunction&) const;

    void swap(FixedVector<T>& other)
    {
        using std::swap;
        swap(m_storage, other.m_storage);
    }

    static ptrdiff_t offsetOfStorage() { return OBJECT_OFFSETOF(FixedVector, m_storage); }

    Storage* storage() { return m_storage.get(); }

private:
    friend class JSC::LLIntOffsetsExtractor;

    std::unique_ptr<Storage> m_storage;
};
static_assert(sizeof(FixedVector<int>) == sizeof(int*));

template<typename T>
template<typename U>
bool FixedVector<T>::contains(const U& value) const
{
    return find(value) != notFound;
}

template<typename T>
template<typename MatchFunction>
size_t FixedVector<T>::findIf(const MatchFunction& matches) const
{
    for (size_t i = 0; i < size(); ++i) {
        if (matches(at(i)))
            return i;
    }
    return notFound;
}

template<typename T>
template<typename U>
size_t FixedVector<T>::find(const U& value) const
{
    return findIf([&](auto& item) {
        return item == value;
    });
}

template<typename T>
inline void swap(FixedVector<T>& a, FixedVector<T>& b)
{
    a.swap(b);
}

template<typename T, typename MapFunction, typename ReturnType = typename std::invoke_result<MapFunction, const T&>::type>
FixedVector<ReturnType> map(const FixedVector<T>& source, MapFunction&& mapFunction)
{
    FixedVector<ReturnType> result(source.size());

    size_t resultIndex = 0;
    for (const auto& item : source) {
        result[resultIndex] = mapFunction(item);
        resultIndex++;
    }

    return result;
}

} // namespace WTF

using WTF::FixedVector;