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/*=========================================================================
Program: CMake - Cross-Platform Makefile Generator
Module: $RCSfile$
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) 2002 Kitware, Inc., Insight Consortium. All rights reserved.
See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef cmGeneratedFileStream_h
#define cmGeneratedFileStream_h
#include "cmStandardIncludes.h"
#include "cmSystemTools.h"
/** \class cmGeneratedFileStream
* \brief Output stream for generated files that does copy-if-different.
*
* Many files generated by CMake don't change each time they are generated.
* This class can be used in place of std::ofstream to open a file and
* write output to it. The class will automatically write output to a
* temporary file and copy it over an existing file only if the generated
* file has changed.
*/
class cmGeneratedFileStream
{
public:
/**
* The constructor takes the name of the file to be generated. It
* automatically generates a name for the temporary file.
*/
cmGeneratedFileStream(const char* name):
m_Name(name),
m_TempName(m_Name+".tmp"),
m_Stream(m_TempName.c_str()),
m_Copied(false),
m_AlwaysCopy(false)
{}
/**
* The destructor ensures that the file has been closed and copied if
* it has changed.
*/
~cmGeneratedFileStream() { this->DoCopy(); }
/**
* Get the real output stream.
*/
std::ostream& GetStream() { return m_Stream; }
/**
* Allow a test for whether the file is open.
*/
operator bool() { return m_Stream.good(); }
/**
* Close the file stream. This will cause the copy-if-different to the
* real file name to occur.
*/
void close() { this->DoCopy(); }
/**
* If always copy is true, then copy the file all the time without
* checking for differences. The default is false.
*/
bool SetAlwaysCopy(bool v) { m_AlwaysCopy = v; return v;}
private:
/**
* The name of the real file where output will be copied if it has changed.
*/
std::string m_Name;
/**
* The name of the temporary file.
*/
std::string m_TempName;
/**
* The real output stream used to write to the file.
*/
std::ofstream m_Stream;
/**
* Whether the temporary file has already been copied to the real file.
*/
bool m_Copied;
/**
* If always copy is true, then copy the file all the time without
* checking for differences. The default is false.
*/
bool m_AlwaysCopy;
/**
* Closes the temporary file and does the copy-if-different to the
* real file.
*/
void DoCopy()
{
if(!m_Copied)
{
m_Stream.close();
if(m_AlwaysCopy)
{
cmSystemTools::cmCopyFile(m_TempName.c_str(), m_Name.c_str());
}
else
{
cmSystemTools::CopyFileIfDifferent(m_TempName.c_str(),
m_Name.c_str());
}
cmSystemTools::RemoveFile(m_TempName.c_str());
m_Copied = true;
}
}
};
/**
* Allow a cmGeneratedFileStream to be used just as a real std::ostream
* would be.
*/
template <class T>
std::ostream& operator << (cmGeneratedFileStream& l, const T& r)
{
std::ostream& os = l.GetStream();
os << r;
return os;
}
#endif
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