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// string_data.h
/* Copyright 2010 10gen Inc.
*
* 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.
*/
#pragma once
#include <algorithm> // for min
#include <cstring>
#include <iosfwd>
#include <limits>
#include <string>
namespace mongo {
using std::string;
/**
* A StringData object wraps a 'const 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 string data can be used to pass a substring around, one should never assume a
* rawData() terminates with a null.
*/
class StringData {
public:
/** Constructs an empty string data */
StringData()
: _data(NULL), _size(0) {}
/**
* Constructs a StringData, for the case where the length of string is not known. 'c'
* must be a pointer to a null-terminated string.
*/
StringData( const char* c )
: _data(c), _size((c == NULL) ? 0 : string::npos) {}
/**
* Constructs a StringData explicitly, for the case where the length of the string is
* already known. 'c' must be a pointer to a null-terminated string, and len must
* be the length that strlen(c) would return, a.k.a the index of the terminator in c.
*/
StringData( const char* c, size_t len )
: _data(c), _size(len) {}
/** Constructs a StringData, for the case of a string. */
StringData( const std::string& s )
: _data(s.c_str()), _size(s.size()) {}
/**
* Constructs a StringData explicitly, for the case of a literal whose size is known at
* compile time.
*/
struct LiteralTag {};
template<size_t N>
StringData( const char (&val)[N], LiteralTag )
: _data(&val[0]), _size(N-1) {}
/**
* Returns -1, 0, or 1 if 'this' is less, equal, or greater than 'other' in
* lexicographical order.
*/
int compare(const StringData& other) const;
/**
* note: this uses tolower, and therefore does not handle
* come languages correctly.
* should be use sparingly
*/
bool equalCaseInsensitive( const 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( const StringData& needle ) const;
size_t rfind( char c, size_t fromPos = string::npos ) const;
/**
* Returns true if 'prefix' is a substring of this instance, anchored at position 0.
*/
bool startsWith( const StringData& prefix ) const;
/**
* Returns true if 'suffix' is a substring of this instance, anchored at the end.
*/
bool endsWith( const 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 { fillSize(); return _size; }
bool empty() const { return size() == 0; }
string toString() const { return 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() (const 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; // is not guaranted to be null terminated (see "notes" above)
mutable size_t _size; // 'size' does not include the null terminator
void fillSize() const {
if (_size == string::npos) {
_size = strlen(_data);
}
}
};
inline bool operator==(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) == 0;
}
inline bool operator!=(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) != 0;
}
inline bool operator<(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) < 0 ;
}
inline bool operator<=(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) <= 0;
}
inline bool operator>(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) > 0;
}
inline bool operator>=(const StringData& lhs, const StringData& rhs) {
return lhs.compare(rhs) >= 0;
}
std::ostream& operator<<(std::ostream& stream, const StringData& value);
} // namespace mongo
#include "mongo/base/string_data-inl.h"
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