1 files changed, 285 insertions, 0 deletions
diff --git a/Source/WTF/wtf/text/StringView.cpp b/Source/WTF/wtf/text/StringView.cpp
new file mode 100644
index 000000000..580799765
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+++ b/Source/WTF/wtf/text/StringView.cpp
@@ -0,0 +1,285 @@
+/*
+
+Copyright (C) 2014-2017 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. 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.
+
+*/
+
+#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