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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <cstdint>
#include <memory>
#include <string>
#include "mongo/base/string_data.h"
#include "mongo/bson/util/builder.h"
#include "mongo/db/fts/unicode/codepoints.h"
namespace mongo {
namespace unicode {
/**
* A string class that support basic Unicode functionality such as removing diacritic marks, and
* lowercasing. The String is constructed with UTF-8 source data, and is converted under the hood to
* a u32string (UTF-32) so operations can be easily done with individual Unicode code points.
*/
class String {
public:
String() = default;
/**
* Construct a String with UTF-8 source data (supports standard C++ string literals, and
* std::strings).
*/
explicit String(StringData utf8_src);
/**
* Reset the String with the new UTF-8 source data, reusing the underlying buffer when possible.
*/
void resetData(const StringData utf8_src);
/**
* Takes a substring of the current String and puts it in another String.
* Overwrites buffer's previous contents rather than appending.
*/
StringData substrToBuf(StackBufBuilder* buffer, size_t pos, size_t len) const;
/**
* Lowercases a substring of the current String and stores the UTF8 result in buffer.
* Overwrites buffer's previous contents rather than appending.
*/
StringData toLowerToBuf(StackBufBuilder* buffer,
CaseFoldMode mode,
size_t offset = 0,
size_t len = std::string::npos) const;
/**
* Returns a UTF-8 encoded std::string version of the String instance. Uses the conversion
* stored in the output buffer when possible.
*/
std::string toString();
/**
* Returns the number Unicode codepoints in the String.
*/
size_t size() const {
return _data.size();
}
/**
* Returns the Unicode codepoint at index i of the String.
*/
const char32_t& operator[](int i) const {
return _data[i];
}
/**
* Options for the substrMatch method.
*/
using SubstrMatchOptions = uint8_t;
/**
* No options (case insensitive and diacritic insensitive).
*/
static const SubstrMatchOptions kNone = 0;
/**
* Perform case sensitive substring match.
*/
static const SubstrMatchOptions kCaseSensitive = 1 << 0;
/**
* Perform diacritic sensitive substring match.
*/
static const SubstrMatchOptions kDiacriticSensitive = 1 << 1;
/**
* Search the string 'str' for the string 'find'. If 'find' exists in 'str', return true, else
* return false. Optionally searches can be made case sensitive and diacritic insensitive. If
* the search is case insensitive, non-Turkish case folding is used unless the
* CaseFoldMode::Turkish is passed to mode.
*/
static bool substrMatch(const std::string& str,
const std::string& find,
SubstrMatchOptions options,
CaseFoldMode mode = CaseFoldMode::kNormal);
/**
* Strips diacritics and case-folds the utf8 input string, as needed to support options.
*
* The options field specifies what operations to *skip*, so kCaseSensitive means to skip case
* folding and kDiacriticSensitive means to skip diacritic striping. If both flags are
* specified, the input utf8 StringData is returned directly without any processing or copying.
*
* If processing is performed, the returned StringData will be placed in buffer. buffer's
* contents (if any) will be replaced. Since we may return the input unmodified the returned
* StringData's lifetime is the shorter of the input utf8 and the next modification to buffer.
* The input utf8 must not point into buffer.
*/
static StringData caseFoldAndStripDiacritics(StackBufBuilder* buffer,
StringData utf8,
SubstrMatchOptions options,
CaseFoldMode mode);
private:
/**
* Helper method for converting a UTF-8 string to a UTF-32 string.
*/
void setData(const StringData utf8_src);
/**
* Unified implementation of substrToBuf and toLowerToBuf.
*/
template <typename Func>
StringData substrToBufWithTransform(StackBufBuilder* buffer,
size_t pos,
size_t len,
Func transform) const;
/**
* The underlying UTF-32 data.
*/
std::u32string _data;
/**
* A buffer for storing the result of the UTF-32 to UTF-8 conversion.
*/
std::string _outputBuf;
/**
* A bool flag that is set to true when toString() will require that the UTF-32 to UTF-8
* conversion be applied again.
*/
bool _needsOutputConversion;
};
} // namespace unicode
} // namespace mongo
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