cmake_m4_preprocessor template

cmake_m4_preprocessor

cmake_minimum_required(VERSION 2.6)
project( test CXX )

# we need the M4 macro processor
find_program( M4_EXECUTABLE m4 DOC "The M4 macro processor" )
if( NOT M4_EXECUTABLE )
   message( SEND_ERROR "Failed to find the M4 macro processor." )
endif( NOT M4_EXECUTABLE )

# - Pass a list of files through the M4 macro processor
#
# ADD_M4_SOURCES( OUTVAR source1 ... sourceN )
#
#  OUTVAR  A list containing all the output file names, suitable
#          to be passed to add_executable or add_library.
#
# If the source files have a .m4 suffix it is stripped from the output
# file name. The output files are placed in the same relative location
# to CMAKE_CURRENT_BINARY_DIR as they are to CMAKE_CURRENT_SOURCE_DIR.
#
# Example:
#  add_m4_sources( SRCS src/test1.cxx.m4 src/test2.cxx.m4 )
#  add_executable( test ${SRCS} )
function( ADD_M4_SOURCES OUTVAR )
   set( outfiles )
   foreach( f ${ARGN} )
     # first we might need to make the input file absolute
     get_filename_component( f "${f}" ABSOLUTE )
     #if( NOT IS_ABSOLUTE "${f}" )
     #  set( f "${CMAKE_CURRENT_SOURCE_DIR}/${f}" )
     #endif( NOT IS_ABSOLUTE "${f}" )
     # get the relative path of the file to the current source dir
     file( RELATIVE_PATH rf "${CMAKE_CURRENT_SOURCE_DIR}" "${f}" )
     # strip the .m4 off the end if present and prepend the current  
binary dir
     string( REGEX REPLACE "\\.m4$" ""  of "$ 
{CMAKE_CURRENT_BINARY_DIR}/${rf}" )
     # append the output file to the list of outputs
     list( APPEND outfiles "${of}" )
     # create the output directory if it doesn't exist
     get_filename_component( d "${of}" PATH )
     if( NOT IS_DIRECTORY "${d}" )
       file( MAKE_DIRECTORY "${d}" )
     endif( NOT IS_DIRECTORY "${d}" )
     # now add the custom command to generate the output file
     add_custom_command( OUTPUT "${of}"
       COMMAND ${M4_EXECUTABLE} ARGS -P -s "${f}" > "${of}"
       DEPENDS "${f}"
       )
   endforeach( f )
   # set the output list in the calling scope
   set( ${OUTVAR} ${outfiles} PARENT_SCOPE )
endfunction( ADD_M4_SOURCES )

add_m4_sources( SRCS src/test1.cxx.m4 src/test2.cxx.m4 )
add_executable( test ${SRCS} )