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// string_data.h
/* Copyright 2010 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <algorithm> // for min
#include <cstring>
#include <iosfwd>
#include <limits>
#include <string>
#define MONGO_INCLUDE_INVARIANT_H_WHITELISTED
#include "mongo/util/invariant.h"
#undef MONGO_INCLUDE_INVARIANT_H_WHITELISTED
namespace mongo {
/**
* A StringData object wraps a 'const std::string&' or a 'const char*' without copying its
* contents. The most common usage is as a function argument that takes any of the two
* forms of strings above. Fundamentally, this class tries go around the fact that string
* literals in C++ are char[N]'s.
*
* Notes:
*
* + The object StringData wraps around must be alive while the StringData is.
*
* + Because std::string data can be used to pass a substring around, one should never assume a
* rawData() terminates with a null.
*/
class StringData {
struct TrustedInitTag {};
StringData(const char* c, size_t len, TrustedInitTag) : _data(c), _size(len) {}
public:
// Declared in string_data_comparator_interface.h.
class ComparatorInterface;
/** Constructs an empty StringData. */
StringData() = default;
/**
* Constructs a StringData, for the case where the length of the
* string is not known. 'c' must either be NULL, or a pointer to a
* null-terminated string.
*/
StringData(const char* str) : StringData(str, str ? std::strlen(str) : 0) {}
/**
* Constructs a StringData explicitly, for the case of a literal
* whose size is known at compile time. Note that you probably
* don't need this on a modern compiler that can see that the call
* to std::strlen on StringData("foo") can be constexpr'ed out.
*/
struct LiteralTag {};
template <size_t N>
StringData(const char (&val)[N], LiteralTag) : StringData(&val[0], N - 1) {}
/**
* Constructs a StringData, for the case of a std::string. We can
* use the trusted init path with no follow on checks because
* string::data is assured to never return nullptr.
*/
StringData(const std::string& s) : StringData(s.data(), s.length(), TrustedInitTag()) {}
/**
* Constructs a StringData with an explicit length. 'c' must
* either be NULL (in which case len must be zero), or be a
* pointer into a character array. The StringData will refer to
* the first 'len' characters starting at 'c'. The range of
* characters c to c+len must be valid.
*/
StringData(const char* c, size_t len) : StringData(c, len, TrustedInitTag()) {
invariant(_data || (_size == 0));
}
/**
* Returns -1, 0, or 1 if 'this' is less, equal, or greater than 'other' in
* lexicographical order.
*/
int compare(StringData other) const;
/**
* note: this uses tolower, and therefore does not handle
* come languages correctly.
* should be use sparingly
*/
bool equalCaseInsensitive(StringData other) const;
void copyTo(char* dest, bool includeEndingNull) const;
StringData substr(size_t pos, size_t n = std::numeric_limits<size_t>::max()) const;
//
// finders
//
size_t find(char c, size_t fromPos = 0) const;
size_t find(StringData needle) const;
size_t rfind(char c, size_t fromPos = std::string::npos) const;
/**
* Returns true if 'prefix' is a substring of this instance, anchored at position 0.
*/
bool startsWith(StringData prefix) const;
/**
* Returns true if 'suffix' is a substring of this instance, anchored at the end.
*/
bool endsWith(StringData suffix) const;
//
// accessors
//
/**
* Get the pointer to the first byte of StringData. This is not guaranteed to be
* null-terminated, so if using this without checking size(), you are likely doing
* something wrong.
*/
const char* rawData() const {
return _data;
}
size_t size() const {
return _size;
}
bool empty() const {
return size() == 0;
}
std::string toString() const {
return std::string(_data, size());
}
char operator[](unsigned pos) const {
return _data[pos];
}
/**
* Functor compatible with std::hash for std::unordered_{map,set}
* Warning: The hash function is subject to change. Do not use in cases where hashes need
* to be consistent across versions.
*/
struct Hasher {
size_t operator()(StringData str) const;
};
//
// iterators
//
typedef const char* const_iterator;
const_iterator begin() const {
return rawData();
}
const_iterator end() const {
return rawData() + size();
}
private:
const char* _data = nullptr; // is not guaranted to be null terminated (see "notes" above)
size_t _size = 0; // 'size' does not include the null terminator
};
inline bool operator==(StringData lhs, StringData rhs) {
return (lhs.size() == rhs.size()) && (lhs.compare(rhs) == 0);
}
inline bool operator!=(StringData lhs, StringData rhs) {
return !(lhs == rhs);
}
inline bool operator<(StringData lhs, StringData rhs) {
return lhs.compare(rhs) < 0;
}
inline bool operator<=(StringData lhs, StringData rhs) {
return lhs.compare(rhs) <= 0;
}
inline bool operator>(StringData lhs, StringData rhs) {
return lhs.compare(rhs) > 0;
}
inline bool operator>=(StringData lhs, StringData rhs) {
return lhs.compare(rhs) >= 0;
}
std::ostream& operator<<(std::ostream& stream, StringData value);
} // namespace mongo
#include "mongo/base/string_data-inl.h"
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