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/*
* Copyright (C) 2009-2019 Apple Inc. All rights reserved.
* Copyright (C) 2012 Google 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/CheckedArithmetic.h>
#include <wtf/text/AtomString.h>
#include <wtf/text/IntegerToStringConversion.h>
#include <wtf/text/StringConcatenateNumbers.h>
#include <wtf/text/StringView.h>
#include <wtf/text/WTFString.h>
namespace WTF {
// StringBuilder currently uses a Checked<int32_t, ConditionalCrashOnOverflow> for m_length.
// Ideally, we would want to make StringBuilder a template with an OverflowHandler parameter, and
// m_length can be instantiated based on that OverflowHandler instead. However, currently, we're
// not able to get clang to export explicitly instantiated template methods (which would be needed
// if we templatize StringBuilder). As a workaround, we use the ConditionalCrashOnOverflow handler
// instead to do a runtime check on whether it should crash on overflows or not.
//
// When clang is able to export explicitly instantiated template methods, we can templatize
// StringBuilder and do away with ConditionalCrashOnOverflow.
// See https://bugs.webkit.org/show_bug.cgi?id=191050.
class StringBuilder {
// Disallow copying since it's expensive and we don't want code to do it by accident.
WTF_MAKE_NONCOPYABLE(StringBuilder);
WTF_MAKE_FAST_ALLOCATED;
public:
enum class OverflowHandler {
CrashOnOverflow,
RecordOverflow
};
StringBuilder(OverflowHandler handler = OverflowHandler::CrashOnOverflow)
: m_bufferCharacters8(nullptr)
{
m_length.setShouldCrashOnOverflow(handler == OverflowHandler::CrashOnOverflow);
}
StringBuilder(StringBuilder&&) = default;
StringBuilder& operator=(StringBuilder&&) = default;
ALWAYS_INLINE void didOverflow() { m_length.overflowed(); }
ALWAYS_INLINE bool hasOverflowed() const { return m_length.hasOverflowed(); }
ALWAYS_INLINE bool crashesOnOverflow() const { return m_length.shouldCrashOnOverflow(); }
WTF_EXPORT_PRIVATE void appendCharacters(const UChar*, unsigned);
WTF_EXPORT_PRIVATE void appendCharacters(const LChar*, unsigned);
ALWAYS_INLINE void appendCharacters(const char* characters, unsigned length) { appendCharacters(reinterpret_cast<const LChar*>(characters), length); }
void append(const AtomString& atomString)
{
append(atomString.string());
}
void append(const String& string)
{
if (hasOverflowed())
return;
if (!string.length())
return;
// If we're appending to an empty string, and there is not a buffer (reserveCapacity has not been called)
// then just retain the string.
if (!m_length && !m_buffer) {
m_string = string;
m_length = string.length();
m_is8Bit = m_string.is8Bit();
return;
}
if (string.is8Bit())
appendCharacters(string.characters8(), string.length());
else
appendCharacters(string.characters16(), string.length());
}
void append(const StringBuilder& other)
{
if (hasOverflowed())
return;
if (other.hasOverflowed())
return didOverflow();
if (!other.m_length)
return;
// If we're appending to an empty string, and there is not a buffer (reserveCapacity has not been called)
// then just retain the string.
if (!m_length && !m_buffer && !other.m_string.isNull()) {
m_string = other.m_string;
m_length = other.m_length;
m_is8Bit = other.m_is8Bit;
return;
}
if (other.is8Bit())
appendCharacters(other.characters8(), other.m_length.unsafeGet());
else
appendCharacters(other.characters16(), other.m_length.unsafeGet());
}
void append(StringView stringView)
{
if (stringView.is8Bit())
appendCharacters(stringView.characters8(), stringView.length());
else
appendCharacters(stringView.characters16(), stringView.length());
}
#if USE(CF)
WTF_EXPORT_PRIVATE void append(CFStringRef);
#endif
#if USE(CF) && defined(__OBJC__)
void append(NSString *string) { append((__bridge CFStringRef)string); }
#endif
void appendSubstring(const String& string, unsigned offset, unsigned length = String::MaxLength)
{
if (offset >= string.length())
return;
unsigned clampedLength = std::min(length, string.length() - offset);
if (string.is8Bit())
appendCharacters(string.characters8() + offset, clampedLength);
else
appendCharacters(string.characters16() + offset, clampedLength);
}
void append(const char* characters)
{
if (characters)
appendCharacters(characters, strlen(characters));
}
void appendCharacter(UChar) = delete;
void append(UChar c)
{
if (hasOverflowed())
return;
unsigned length = m_length.unsafeGet<unsigned>();
if (m_buffer && length < m_buffer->length() && m_string.isNull()) {
if (!m_is8Bit) {
m_bufferCharacters16[length] = c;
m_length++;
return;
}
if (isLatin1(c)) {
m_bufferCharacters8[length] = static_cast<LChar>(c);
m_length++;
return;
}
}
appendCharacters(&c, 1);
}
void appendCharacter(LChar) = delete;
void append(LChar c)
{
if (hasOverflowed())
return;
unsigned length = m_length.unsafeGet<unsigned>();
if (m_buffer && length < m_buffer->length() && m_string.isNull()) {
if (m_is8Bit)
m_bufferCharacters8[length] = c;
else
m_bufferCharacters16[length] = c;
m_length++;
} else
appendCharacters(&c, 1);
}
void appendCharacter(char) = delete;
void append(char c)
{
append(static_cast<LChar>(c));
}
void appendCharacter(UChar32 c)
{
if (U_IS_BMP(c)) {
append(static_cast<UChar>(c));
return;
}
append(U16_LEAD(c));
append(U16_TRAIL(c));
}
WTF_EXPORT_PRIVATE void appendQuotedJSONString(const String&);
template<unsigned characterCount>
ALWAYS_INLINE void appendLiteral(const char (&characters)[characterCount]) { appendCharacters(characters, characterCount - 1); }
WTF_EXPORT_PRIVATE void appendNumber(int);
WTF_EXPORT_PRIVATE void appendNumber(unsigned);
WTF_EXPORT_PRIVATE void appendNumber(long);
WTF_EXPORT_PRIVATE void appendNumber(unsigned long);
WTF_EXPORT_PRIVATE void appendNumber(long long);
WTF_EXPORT_PRIVATE void appendNumber(unsigned long long);
WTF_EXPORT_PRIVATE void appendNumber(float);
WTF_EXPORT_PRIVATE void appendNumber(double);
template<typename... StringTypes> void append(StringTypes...);
String toString()
{
if (!m_string.isNull()) {
ASSERT(!m_buffer || m_isReified);
ASSERT(!hasOverflowed());
return m_string;
}
RELEASE_ASSERT(!hasOverflowed());
shrinkToFit();
reifyString();
return m_string;
}
const String& toStringPreserveCapacity() const
{
RELEASE_ASSERT(!hasOverflowed());
if (m_string.isNull())
reifyString();
return m_string;
}
AtomString toAtomString() const
{
RELEASE_ASSERT(!hasOverflowed());
if (!m_length)
return emptyAtom();
// If the buffer is sufficiently over-allocated, make a new AtomString from a copy so its buffer is not so large.
if (canShrink()) {
if (is8Bit())
return AtomString(characters8(), length());
return AtomString(characters16(), length());
}
if (!m_string.isNull())
return AtomString(m_string);
ASSERT(m_buffer);
return AtomString(m_buffer.get(), 0, m_length.unsafeGet());
}
unsigned length() const
{
RELEASE_ASSERT(!hasOverflowed());
return m_length.unsafeGet();
}
bool isEmpty() const { return !m_length; }
WTF_EXPORT_PRIVATE void reserveCapacity(unsigned newCapacity);
unsigned capacity() const
{
RELEASE_ASSERT(!hasOverflowed());
return m_buffer ? m_buffer->length() : m_length.unsafeGet();
}
WTF_EXPORT_PRIVATE void resize(unsigned newSize);
WTF_EXPORT_PRIVATE bool canShrink() const;
WTF_EXPORT_PRIVATE void shrinkToFit();
UChar operator[](unsigned i) const
{
RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!hasOverflowed() && i < m_length.unsafeGet<unsigned>());
if (m_is8Bit)
return characters8()[i];
return characters16()[i];
}
const LChar* characters8() const
{
ASSERT(m_is8Bit);
if (!m_length)
return nullptr;
if (!m_string.isNull())
return m_string.characters8();
ASSERT(m_buffer);
return m_buffer->characters8();
}
const UChar* characters16() const
{
ASSERT(!m_is8Bit);
if (!m_length)
return nullptr;
if (!m_string.isNull())
return m_string.characters16();
ASSERT(m_buffer);
return m_buffer->characters16();
}
bool is8Bit() const { return m_is8Bit; }
void clear()
{
m_length = 0;
m_string = String();
m_buffer = nullptr;
m_bufferCharacters8 = nullptr;
m_is8Bit = true;
}
void swap(StringBuilder& stringBuilder)
{
std::swap(m_length, stringBuilder.m_length);
m_string.swap(stringBuilder.m_string);
m_buffer.swap(stringBuilder.m_buffer);
std::swap(m_is8Bit, stringBuilder.m_is8Bit);
std::swap(m_bufferCharacters8, stringBuilder.m_bufferCharacters8);
ASSERT(!m_buffer || hasOverflowed() || m_buffer->length() >= m_length.unsafeGet<unsigned>());
}
private:
void allocateBuffer(const LChar* currentCharacters, unsigned requiredLength);
void allocateBuffer(const UChar* currentCharacters, unsigned requiredLength);
void allocateBufferUpConvert(const LChar* currentCharacters, unsigned requiredLength);
template<typename CharacterType> void reallocateBuffer(unsigned requiredLength);
template<typename CharacterType> ALWAYS_INLINE CharacterType* extendBufferForAppending(unsigned additionalLength);
template<typename CharacterType> ALWAYS_INLINE CharacterType* extendBufferForAppendingWithoutOverflowCheck(CheckedInt32 requiredLength);
template<typename CharacterType> CharacterType* extendBufferForAppendingSlowCase(unsigned requiredLength);
WTF_EXPORT_PRIVATE LChar* extendBufferForAppending8(CheckedInt32 requiredLength);
WTF_EXPORT_PRIVATE UChar* extendBufferForAppending16(CheckedInt32 requiredLength);
template<typename CharacterType> ALWAYS_INLINE CharacterType* getBufferCharacters();
WTF_EXPORT_PRIVATE void reifyString() const;
template<typename... StringTypeAdapters> void appendFromAdapters(StringTypeAdapters...);
mutable String m_string;
RefPtr<StringImpl> m_buffer;
union {
LChar* m_bufferCharacters8;
UChar* m_bufferCharacters16;
};
static_assert(String::MaxLength == std::numeric_limits<int32_t>::max(), "");
Checked<int32_t, ConditionalCrashOnOverflow> m_length;
bool m_is8Bit { true };
#if ASSERT_ENABLED
mutable bool m_isReified { false };
#endif
};
template<>
ALWAYS_INLINE LChar* StringBuilder::getBufferCharacters<LChar>()
{
ASSERT(m_is8Bit);
return m_bufferCharacters8;
}
template<>
ALWAYS_INLINE UChar* StringBuilder::getBufferCharacters<UChar>()
{
ASSERT(!m_is8Bit);
return m_bufferCharacters16;
}
template<typename... StringTypeAdapters>
void StringBuilder::appendFromAdapters(StringTypeAdapters... adapters)
{
auto requiredLength = checkedSum<int32_t>(m_length, adapters.length()...);
if (m_is8Bit && are8Bit(adapters...)) {
LChar* destination = extendBufferForAppending8(requiredLength);
if (!destination) {
ASSERT(hasOverflowed());
return;
}
stringTypeAdapterAccumulator(destination, adapters...);
} else {
UChar* destination = extendBufferForAppending16(requiredLength);
if (!destination) {
ASSERT(hasOverflowed());
return;
}
stringTypeAdapterAccumulator(destination, adapters...);
}
}
template<typename... StringTypes>
void StringBuilder::append(StringTypes... strings)
{
appendFromAdapters(StringTypeAdapter<StringTypes>(strings)...);
}
template<typename CharacterType>
bool equal(const StringBuilder& s, const CharacterType* buffer, unsigned length)
{
if (s.length() != length)
return false;
if (s.is8Bit())
return equal(s.characters8(), buffer, length);
return equal(s.characters16(), buffer, length);
}
template<typename StringType>
bool equal(const StringBuilder& a, const StringType& b)
{
if (a.length() != b.length())
return false;
if (!a.length())
return true;
if (a.is8Bit()) {
if (b.is8Bit())
return equal(a.characters8(), b.characters8(), a.length());
return equal(a.characters8(), b.characters16(), a.length());
}
if (b.is8Bit())
return equal(a.characters16(), b.characters8(), a.length());
return equal(a.characters16(), b.characters16(), a.length());
}
inline bool operator==(const StringBuilder& a, const StringBuilder& b) { return equal(a, b); }
inline bool operator!=(const StringBuilder& a, const StringBuilder& b) { return !equal(a, b); }
inline bool operator==(const StringBuilder& a, const String& b) { return equal(a, b); }
inline bool operator!=(const StringBuilder& a, const String& b) { return !equal(a, b); }
inline bool operator==(const String& a, const StringBuilder& b) { return equal(b, a); }
inline bool operator!=(const String& a, const StringBuilder& b) { return !equal(b, a); }
template<> struct IntegerToStringConversionTrait<StringBuilder> {
using ReturnType = void;
using AdditionalArgumentType = StringBuilder;
static void flush(LChar* characters, unsigned length, StringBuilder* stringBuilder) { stringBuilder->appendCharacters(characters, length); }
};
} // namespace WTF
using WTF::StringBuilder;