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// stringdata.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 <string>
#include <cstring>
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.
*
* Note that the object StringData wraps around must be alive while the StringData
* is.
*/
class StringData {
public:
/** Construct 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((unsigned) strlen(c)) {}
/** Construct 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 strlenOfc
* must be the length that std::strlen(c) would return, a.k.a the index of the
* terminator in c.
*/
StringData( const char* c, unsigned len )
: _data(c), _size(len) {}
/** Construct a StringData, for the case of a std::string. */
StringData( const string& s )
: _data(s.c_str()), _size((unsigned) s.size()) {}
// Construct 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) {}
// accessors
const char* data() const { return _data; }
unsigned size() const { return _size; }
private:
const char* const _data; // is always null terminated
const unsigned _size; // 'size' does not include the null terminator
};
} // namespace mongo
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