PerformanceTests/StitchMarker/wtf/text/StringView.cpp

/*

Copyright (C) 2014-2017 Apple Inc. All rights reserved.

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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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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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*/

#include "config.h"
#include "StringView.h"

#include <mutex>
#include <unicode/ubrk.h>
#include <wtf/HashMap.h>
#include <wtf/Lock.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/Optional.h>
#include <wtf/text/TextBreakIterator.h>
#include <wtf/unicode/UTF8.h>

namespace WTF {

using namespace Unicode;

bool StringView::containsIgnoringASCIICase(const StringView& matchString) const
{
    return findIgnoringASCIICase(matchString) != notFound;
}

bool StringView::containsIgnoringASCIICase(const StringView& matchString, unsigned startOffset) const
{
    return findIgnoringASCIICase(matchString, startOffset) != notFound;
}

size_t StringView::findIgnoringASCIICase(const StringView& matchString) const
{
    return ::WTF::findIgnoringASCIICase(*this, matchString, 0);
}

size_t StringView::findIgnoringASCIICase(const StringView& matchString, unsigned startOffset) const
{
    return ::WTF::findIgnoringASCIICase(*this, matchString, startOffset);
}

bool StringView::startsWith(const StringView& prefix) const
{
    return ::WTF::startsWith(*this, prefix);
}

bool StringView::startsWithIgnoringASCIICase(const StringView& prefix) const
{
    return ::WTF::startsWithIgnoringASCIICase(*this, prefix);
}

bool StringView::endsWith(const StringView& suffix) const
{
    return ::WTF::endsWith(*this, suffix);
}

bool StringView::endsWithIgnoringASCIICase(const StringView& suffix) const
{
    return ::WTF::endsWithIgnoringASCIICase(*this, suffix);
}

CString StringView::utf8(ConversionMode mode) const
{
    if (isNull())
        return CString("", 0);
    if (is8Bit())
        return StringImpl::utf8ForCharacters(characters8(), length());
    return StringImpl::utf8ForCharacters(characters16(), length(), mode);
}

size_t StringView::find(StringView matchString, unsigned start) const
{
    return findCommon(*this, matchString, start);
}

void StringView::SplitResult::Iterator::findNextSubstring()
{
    for (size_t separatorPosition; (separatorPosition = m_result.m_string.find(m_result.m_separator, m_position)) != notFound; ++m_position) {
        if (separatorPosition > m_position) {
            m_length = separatorPosition - m_position;
            return;
        }
    }
    m_length = m_result.m_string.length() - m_position;
}

auto StringView::SplitResult::Iterator::operator++() -> Iterator&
{
    ASSERT(m_position < m_result.m_string.length());
    m_position += m_length;
    if (m_position < m_result.m_string.length()) {
        ++m_position;
        findNextSubstring();
    }
    return *this;
}

class StringView::GraphemeClusters::Iterator::Impl {
public:
    Impl(const StringView& stringView, std::optional<NonSharedCharacterBreakIterator>&& iterator, unsigned index)
        : m_stringView(stringView)
        , m_iterator(WTFMove(iterator))
        , m_index(index)
        , m_indexEnd(computeIndexEnd())
    {
    }

    void operator++()
    {
        ASSERT(m_indexEnd > m_index);
        m_index = m_indexEnd;
        m_indexEnd = computeIndexEnd();
    }

    StringView operator*() const
    {
        if (m_stringView.is8Bit())
            return StringView(m_stringView.characters8() + m_index, m_indexEnd - m_index);
        return StringView(m_stringView.characters16() + m_index, m_indexEnd - m_index);
    }

    bool operator==(const Impl& other) const
    {
        ASSERT(&m_stringView == &other.m_stringView);
        auto result = m_index == other.m_index;
        ASSERT(!result || m_indexEnd == other.m_indexEnd);
        return result;
    }

    unsigned computeIndexEnd()
    {
        if (!m_iterator)
            return 0;
        if (m_index == m_stringView.length())
            return m_index;
        return ubrk_following(m_iterator.value(), m_index);
    }

private:
    const StringView& m_stringView;
    std::optional<NonSharedCharacterBreakIterator> m_iterator;
    unsigned m_index;
    unsigned m_indexEnd;
};

StringView::GraphemeClusters::Iterator::Iterator(const StringView& stringView, unsigned index)
    : m_impl(std::make_unique<Impl>(stringView, stringView.isNull() ? std::nullopt : std::optional<NonSharedCharacterBreakIterator>(NonSharedCharacterBreakIterator(stringView)), index))
{
}

StringView::GraphemeClusters::Iterator::~Iterator()
{
}

StringView::GraphemeClusters::Iterator::Iterator(Iterator&& other)
    : m_impl(WTFMove(other.m_impl))
{
}

auto StringView::GraphemeClusters::Iterator::operator++() -> Iterator&
{
    ++(*m_impl);
    return *this;
}

StringView StringView::GraphemeClusters::Iterator::operator*() const
{
    return **m_impl;
}

bool StringView::GraphemeClusters::Iterator::operator==(const Iterator& other) const
{
    return *m_impl == *(other.m_impl);
}

bool StringView::GraphemeClusters::Iterator::operator!=(const Iterator& other) const
{
    return !(*this == other);
}

#if CHECK_STRINGVIEW_LIFETIME

// Manage reference count manually so UnderlyingString does not need to be defined in the header.

struct StringView::UnderlyingString {
    std::atomic_uint refCount { 1u };
    bool isValid { true };
    const StringImpl& string;
    explicit UnderlyingString(const StringImpl&);
};

StringView::UnderlyingString::UnderlyingString(const StringImpl& string)
    : string(string)
{
}

static StaticLock underlyingStringsMutex;

static HashMap<const StringImpl*, StringView::UnderlyingString*>& underlyingStrings()
{
    static NeverDestroyed<HashMap<const StringImpl*, StringView::UnderlyingString*>> map;
    return map;
}

void StringView::invalidate(const StringImpl& stringToBeDestroyed)
{
    UnderlyingString* underlyingString;
    {
        std::lock_guard<StaticLock> lock(underlyingStringsMutex);
        underlyingString = underlyingStrings().take(&stringToBeDestroyed);
        if (!underlyingString)
            return;
    }
    ASSERT(underlyingString->isValid);
    underlyingString->isValid = false;
}

bool StringView::underlyingStringIsValid() const
{
    return !m_underlyingString || m_underlyingString->isValid;
}

void StringView::adoptUnderlyingString(UnderlyingString* underlyingString)
{
    if (m_underlyingString) {
        std::lock_guard<StaticLock> lock(underlyingStringsMutex);
        if (!--m_underlyingString->refCount) {
            if (m_underlyingString->isValid) {
                underlyingStrings().remove(&m_underlyingString->string);
            }
            delete m_underlyingString;
        }
    }
    m_underlyingString = underlyingString;
}

void StringView::setUnderlyingString(const StringImpl* string)
{
    UnderlyingString* underlyingString;
    if (!string)
        underlyingString = nullptr;
    else {
        std::lock_guard<StaticLock> lock(underlyingStringsMutex);
        auto result = underlyingStrings().add(string, nullptr);
        if (result.isNewEntry)
            result.iterator->value = new UnderlyingString(*string);
        else
            ++result.iterator->value->refCount;
        underlyingString = result.iterator->value;
    }
    adoptUnderlyingString(underlyingString);
}

void StringView::setUnderlyingString(const StringView& otherString)
{
    UnderlyingString* underlyingString = otherString.m_underlyingString;
    if (underlyingString)
        ++underlyingString->refCount;
    adoptUnderlyingString(underlyingString);
}

#endif // CHECK_STRINGVIEW_LIFETIME

} // namespace WTF