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/**
* @file stringize.h
* @author Nat Goodspeed
* @date 2008-12-17
* @brief stringize(item) template function and STRINGIZE(expression) macro
*
* $LicenseInfo:firstyear=2008&license=viewergpl$
* Copyright (c) 2008, Linden Research, Inc.
* $/LicenseInfo$
*/
#if ! defined(LL_STRINGIZE_H)
#define LL_STRINGIZE_H
#include <sstream>
/**
* stringize(item) encapsulates an idiom we use constantly, using
* operator<<(std::ostringstream&, TYPE) followed by std::ostringstream::str()
* to render a string expressing some item.
*/
template <typename T>
std::string stringize(const T& item)
{
std::ostringstream out;
out << item;
return out.str();
}
/**
* STRINGIZE(item1 << item2 << item3 ...) effectively expands to the
* following:
* @code
* std::ostringstream out;
* out << item1 << item2 << item3 ... ;
* return out.str();
* @endcode
*/
#define STRINGIZE(EXPRESSION) (static_cast<std::ostringstream&>(Stringize() << EXPRESSION).str())
/**
* Helper class for STRINGIZE() macro. Ideally the body of
* STRINGIZE(EXPRESSION) would look something like this:
* @code
* (std::ostringstream() << EXPRESSION).str()
* @endcode
* That doesn't work because each of the relevant operator<<() functions
* accepts a non-const std::ostream&, to which you can't pass a temp instance
* of std::ostringstream. Stringize plays the necessary const tricks to make
* the whole thing work.
*/
class Stringize
{
public:
/**
* This is the essence of Stringize. The leftmost << operator (the one
* coded in the STRINGIZE() macro) engages this operator<<() const method
* on the temp Stringize instance. Every other << operator (ones embedded
* in EXPRESSION) simply sees the std::ostream& returned by the first one.
*
* Finally, the STRINGIZE() macro downcasts that std::ostream& to
* std::ostringstream&.
*/
template <typename T>
std::ostream& operator<<(const T& item) const
{
mOut << item;
return mOut;
}
private:
mutable std::ostringstream mOut;
};
#endif /* ! defined(LL_STRINGIZE_H) */
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