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// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_STRING_COMPARATOR_H_
#define V8_OBJECTS_STRING_COMPARATOR_H_
#include "src/base/logging.h"
#include "src/common/globals.h"
#include "src/objects/string.h"
#include "src/utils/utils.h"
namespace v8 {
namespace internal {
// Compares the contents of two strings by reading and comparing
// int-sized blocks of characters.
template <typename Char>
static inline bool CompareRawStringContents(const Char* const a,
const Char* const b, int length) {
return CompareChars(a, b, length) == 0;
}
template <typename Chars1, typename Chars2>
class RawStringComparator : public AllStatic {
public:
static inline bool compare(const Chars1* a, const Chars2* b, int len) {
DCHECK(sizeof(Chars1) != sizeof(Chars2));
for (int i = 0; i < len; i++) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
};
template <>
class RawStringComparator<uint16_t, uint16_t> {
public:
static inline bool compare(const uint16_t* a, const uint16_t* b, int len) {
return CompareRawStringContents(a, b, len);
}
};
template <>
class RawStringComparator<uint8_t, uint8_t> {
public:
static inline bool compare(const uint8_t* a, const uint8_t* b, int len) {
return CompareRawStringContents(a, b, len);
}
};
class StringComparator {
class State {
public:
State() : is_one_byte_(true), length_(0), buffer8_(nullptr) {}
void Init(String string);
inline void VisitOneByteString(const uint8_t* chars, int length) {
is_one_byte_ = true;
buffer8_ = chars;
length_ = length;
}
inline void VisitTwoByteString(const uint16_t* chars, int length) {
is_one_byte_ = false;
buffer16_ = chars;
length_ = length;
}
void Advance(int consumed);
ConsStringIterator iter_;
bool is_one_byte_;
int length_;
union {
const uint8_t* buffer8_;
const uint16_t* buffer16_;
};
private:
DISALLOW_COPY_AND_ASSIGN(State);
};
public:
inline StringComparator() = default;
template <typename Chars1, typename Chars2>
static inline bool Equals(State* state_1, State* state_2, int to_check) {
const Chars1* a = reinterpret_cast<const Chars1*>(state_1->buffer8_);
const Chars2* b = reinterpret_cast<const Chars2*>(state_2->buffer8_);
return RawStringComparator<Chars1, Chars2>::compare(a, b, to_check);
}
bool Equals(String string_1, String string_2);
private:
State state_1_;
State state_2_;
DISALLOW_COPY_AND_ASSIGN(StringComparator);
};
} // namespace internal
} // namespace v8
#endif // V8_OBJECTS_STRING_COMPARATOR_H_