GPP is a general-purpose preprocessor with customizable syntax, suitable for a wide range of preprocessing tasks. Its independence from any one programming language makes it much more versatile than the C preprocessor (cpp), while its syntax is lighter and more flexible than that of GNU m4. There are built-in macros for use with C/C++, LaTeX, HTML, XHTML, and Prolog files.

GPP is Free Software. It is distributed under the terms of the GNU Lesser General Public Licence.

You can download portable source packages (as .tar.bz2 files) for the current and previous releases on GitHub or nothingisreal.com.

Alternatively, you can browse, download, or clone the development version on GitHub, though note that if you do this you will need to manually set up the build system using the GNU Autotools rather than using the end-user installation instructions described below.

To configure, build, and install from the portable source packages, see the included INSTALL file. (In brief, ./configure && make && make install should work in most cases, provided you have make and a C compiler installed.)

For other systems, including Microsoft Windows, you may be able to follow the INSTALL instructions with the help of a Unix-like environment such as Cygwin or MSYS. Failing that, copy the file config.h.in to src/config.h. Open the file and follow the instructions inside to modify it based on your system's capabilities. Then use a C compiler to compile the gpp.c file in the src subdirectory with the macro HAVE_CONFIG_H defined. On Microsoft Windows systems, you may need to also define the macro WIN_NT if your compiler does not already define it by default.

Links to binary packages for various operating systems are available on the GPP home page.

Extensive documentation, including usage examples, is included in the portable source package and should get installed automatically as a man page and an HTML file. The HTML version is also available online on the GPP home page.

Note that the documentation itself is generated by GPP using an input file (gpp.pp) with macros that can automatically produce HTML, LaTeX, or troff (man page) output. Studying this file should prove instructive, and manually running it through GPP can serve as a basic test of the program's functionality. Once you have installed GPP, you can invoke it as follows to get instructions on how to manually generate the documentation: gpp -H /path/to/gpp.pp

To refer to GPP in a publication, please use the following citation:

Tristan Miller and Denis Auroux. GPP, the generic preprocessor. Journal of Open Source Software, 5(51), July 2020. ISSN 2475-9066. DOI: 10.21105/joss.02400.

Contributions are welcome. Please post bug reports, feature requests, and support requests on the issue tracker. Feel free to fork the project and send pull requests for integration into the main distribution.