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// Copyright (C) 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ICING_UTIL_CHARACTER_ITERATOR_H_
#define ICING_UTIL_CHARACTER_ITERATOR_H_
#include "icing/legacy/core/icing-string-util.h"
#include "icing/util/i18n-utils.h"
namespace icing {
namespace lib {
class CharacterIterator {
public:
explicit CharacterIterator(std::string_view text)
: CharacterIterator(text, 0, 0, 0) {}
CharacterIterator(std::string_view text, int utf8_index, int utf16_index,
int utf32_index)
: text_(text),
cached_current_char_(i18n_utils::kInvalidUChar32),
utf8_index_(utf8_index),
utf16_index_(utf16_index),
utf32_index_(utf32_index) {}
// Returns the character that the iterator currently points to.
// i18n_utils::kInvalidUChar32 if unable to read that character.
UChar32 GetCurrentChar();
// Moves current position to desired_utf8_index.
// REQUIRES: 0 <= desired_utf8_index <= text_.length()
bool MoveToUtf8(int desired_utf8_index);
// Advances from current position to the character that includes the specified
// UTF-8 index.
// REQUIRES: desired_utf8_index <= text_.length()
// desired_utf8_index is allowed to point one index past the end, but no
// further.
bool AdvanceToUtf8(int desired_utf8_index);
// Rewinds from current position to the character that includes the specified
// UTF-8 index.
// REQUIRES: 0 <= desired_utf8_index
bool RewindToUtf8(int desired_utf8_index);
// Moves current position to desired_utf16_index.
// REQUIRES: 0 <= desired_utf16_index <= text_.utf16_length()
bool MoveToUtf16(int desired_utf16_index);
// Advances current position to desired_utf16_index.
// REQUIRES: desired_utf16_index <= text_.utf16_length()
// desired_utf16_index is allowed to point one index past the end, but no
// further.
bool AdvanceToUtf16(int desired_utf16_index);
// Rewinds current position to desired_utf16_index.
// REQUIRES: 0 <= desired_utf16_index
bool RewindToUtf16(int desired_utf16_index);
// Moves current position to desired_utf32_index.
// REQUIRES: 0 <= desired_utf32_index <= text_.utf32_length()
bool MoveToUtf32(int desired_utf32_index);
// Advances current position to desired_utf32_index.
// REQUIRES: desired_utf32_index <= text_.utf32_length()
// desired_utf32_index is allowed to point one index past the end, but no
// further.
bool AdvanceToUtf32(int desired_utf32_index);
// Rewinds current position to desired_utf32_index.
// REQUIRES: 0 <= desired_utf32_index
bool RewindToUtf32(int desired_utf32_index);
int utf8_index() const { return utf8_index_; }
int utf16_index() const { return utf16_index_; }
int utf32_index() const { return utf32_index_; }
bool operator==(const CharacterIterator& rhs) const {
// cached_current_char_ is just that: a cached value. As such, it's not
// considered for equality.
return text_ == rhs.text_ && utf8_index_ == rhs.utf8_index_ &&
utf16_index_ == rhs.utf16_index_ && utf32_index_ == rhs.utf32_index_;
}
std::string DebugString() const {
return IcingStringUtil::StringPrintf("(u8:%d,u16:%d,u32:%d)", utf8_index_,
utf16_index_, utf32_index_);
}
private:
// Resets the character iterator to the start of the text if any of the
// indices are negative.
void ResetToStartIfNecessary();
std::string_view text_;
UChar32 cached_current_char_;
int utf8_index_;
int utf16_index_;
int utf32_index_;
};
} // namespace lib
} // namespace icing
#endif // ICING_UTIL_CHARACTER_ITERATOR_H_
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