Commit 8011fe0f authored by Brad King's avatar Brad King

ENH: cmGeneratedFileStream class added to simplify copy-if-different usage on generated files.

parent b9cfc413
/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: $RCSfile$
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) 2001 Insight Consortium
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* The name of the Insight Consortium, nor the names of any consortium members,
nor of any contributors, may be used to endorse or promote products derived
from this software without specific prior written permission.
* Modified source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
=========================================================================*/
#ifndef cmGeneratedFileStream_h
#define cmGeneratedFileStream_h
#include "cmStandardIncludes.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)
{}
/**
* 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() const { return m_Stream; }
/**
* Close the file stream. This will cause the copy-if-different to the
* real file name to occur.
*/
void close() { this->DoCopy(); }
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;
/**
* Closes the temporary file and does the copy-if-different to the real file.
*/
void DoCopy()
{
if(!m_Copied)
{
m_Stream.close();
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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