#
# Defines a list of files with a given name, prepends the relative path to the
# source dir to each file if available and passes the list to PARENT_SCOPE.
#
# Usage:
#	add_files(
#		NAME_OF_FILES
#		file1.cpp
#		file2.cpp
#		...
#		)
#
macro(add_files var_name)
	if(DEFINED SRC_DIR)
		file (RELATIVE_PATH _relPath "${SRC_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}")
	else()
		file (RELATIVE_PATH _relPath "${CMAKE_SOURCE_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}")
	endif()

	foreach (_src ${ARGN})
		if (_relPath)
			list (APPEND ${var_name} "${_relPath}/${_src}")
		else()
			list (APPEND ${var_name} "${_src}")
		endif()
	endforeach()

	if (_relPath)
		set(${var_name} ${${var_name}} PARENT_SCOPE)
	else()
		set(${var_name} ${${var_name}})
	endif()
endmacro()