# use bison for .yy files

# search for bison
MACRO(FIND_BISON)
    IF(NOT BISON_EXECUTABLE)
        FIND_PROGRAM(BISON_EXECUTABLE bison)
        IF (NOT BISON_EXECUTABLE)
        
	  MESSAGE(FATAL_ERROR "Bison not found - aborting")
	
	ELSE (NOT BISON_EXECUTABLE)

          EXEC_PROGRAM(${BISON_EXECUTABLE} ARGS --version OUTPUT_VARIABLE BISON_VERSION_STR)
          # get first line in case it's multiline
          STRING(REGEX REPLACE "([^\n]+).*" "\\1" FIRST_LINE "${BISON_VERSION_STR}")
          # get version information
          STRING(REGEX REPLACE ".* ([0-9]+)\\.([0-9]+)" "\\1" BISON_VERSION_MAJOR "${FIRST_LINE}")
          STRING(REGEX REPLACE ".* ([0-9]+)\\.([0-9]+)" "\\2" BISON_VERSION_MINOR "${FIRST_LINE}")
          IF (BISON_VERSION_MAJOR LESS 2)
            MESSAGE (FATAL_ERROR "Bison version is too old (${BISON_VERSION_MAJOR}.${BISON_VERSION_MINOR}). Use 2.0 or higher.")
          ENDIF (BISON_VERSION_MAJOR LESS 2)

      ENDIF (NOT BISON_EXECUTABLE)
    ENDIF(NOT BISON_EXECUTABLE)

ENDMACRO(FIND_BISON)

MACRO(ADD_BISON_FILES _sources )
    FIND_BISON()

    FOREACH (_current_FILE ${ARGN})
      GET_FILENAME_COMPONENT(_in ${_current_FILE} ABSOLUTE)
      GET_FILENAME_COMPONENT(_basename ${_current_FILE} NAME_WE)

      SET(_out ${CMAKE_CURRENT_BINARY_DIR}/${_basename}.cpp)
      SET(_out_h ${CMAKE_CURRENT_BINARY_DIR}/${_basename}.h)  	 
      SET(_out_hpp ${CMAKE_CURRENT_BINARY_DIR}/${_basename}.hpp)

		# bison options:
		# -t add debugging facilities
		# -d produce additional header file (used in parser.l)
		# -v produce additional *.output file with parser states

      ADD_CUSTOM_COMMAND(
         OUTPUT ${_out}
         COMMAND ${BISON_EXECUTABLE}
         ARGS
         -o${_out} -d -v -t
         ${_in}
         DEPENDS ${_in}
      )

      # Hack to change output file name to <include_file>.h
      # instead of <include_file>.hpp
      # (Instead of changing source code)

      ADD_CUSTOM_COMMAND(  	 
         OUTPUT ${_out_h} 	 
         COMMAND ${CMAKE_COMMAND} 	 
         ARGS 	 
         -E copy ${_out_hpp} ${_out_h} 	 
         DEPENDS ${_out} 	 
      )

      SET(${_sources} ${${_sources}} ${_out} ${_out_h} )
   ENDFOREACH (_current_FILE)
ENDMACRO(ADD_BISON_FILES)