# - Check if the given C++ source code compiles.
# CHECK_CXX_SOURCE_COMPILES(<code> <var> [FAIL_REGEX <fail-regex>])
#  <code>       - source code to try to compile
#  <var>        - variable to store whether the source code compiled
#  <fail-regex> - fail if test output matches this regex
# The following variables may be set before calling this macro to
# modify the way the check is run:
#
#  CMAKE_REQUIRED_FLAGS = string of compile command line flags
#  CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
#  CMAKE_REQUIRED_INCLUDES = list of include directories
#  CMAKE_REQUIRED_LIBRARIES = list of libraries to link

MACRO(CHECK_CXX_SOURCE_COMPILES SOURCE VAR)
  IF("${VAR}" MATCHES "^${VAR}$")
    SET(_FAIL_REGEX)
    SET(_key)
    FOREACH(arg ${ARGN})
      IF("${arg}" MATCHES "^(FAIL_REGEX)$")
        SET(_key "${arg}")
      ELSEIF(_key)
        LIST(APPEND _${_key} "${arg}")
      ELSE()
        MESSAGE(FATAL_ERROR "Unknown argument:\n  ${arg}\n")
      ENDIF()
    ENDFOREACH()

    SET(MACRO_CHECK_FUNCTION_DEFINITIONS
      "-D${VAR} ${CMAKE_REQUIRED_FLAGS}")
    IF(CMAKE_REQUIRED_LIBRARIES)
      SET(CHECK_CXX_SOURCE_COMPILES_ADD_LIBRARIES
        "-DLINK_LIBRARIES:STRING=${CMAKE_REQUIRED_LIBRARIES}")
    ELSE(CMAKE_REQUIRED_LIBRARIES)
      SET(CHECK_CXX_SOURCE_COMPILES_ADD_LIBRARIES)
    ENDIF(CMAKE_REQUIRED_LIBRARIES)
    IF(CMAKE_REQUIRED_INCLUDES)
      SET(CHECK_CXX_SOURCE_COMPILES_ADD_INCLUDES
        "-DINCLUDE_DIRECTORIES:STRING=${CMAKE_REQUIRED_INCLUDES}")
    ELSE(CMAKE_REQUIRED_INCLUDES)
      SET(CHECK_CXX_SOURCE_COMPILES_ADD_INCLUDES)
    ENDIF(CMAKE_REQUIRED_INCLUDES)
    FILE(WRITE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.cxx"
      "${SOURCE}\n")

    MESSAGE(STATUS "Performing Test ${VAR}")
    TRY_COMPILE(${VAR}
      ${CMAKE_BINARY_DIR}
      ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.cxx
      COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
      CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_FUNCTION_DEFINITIONS}
      "${CHECK_CXX_SOURCE_COMPILES_ADD_LIBRARIES}"
      "${CHECK_CXX_SOURCE_COMPILES_ADD_INCLUDES}"
      OUTPUT_VARIABLE OUTPUT)

    FOREACH(_regex ${_FAIL_REGEX})
      IF("${OUTPUT}" MATCHES "${_regex}")
        SET(${VAR} 0)
      ENDIF()
    ENDFOREACH()

    IF(${VAR})
      SET(${VAR} 1 CACHE INTERNAL "Test ${VAR}")
      MESSAGE(STATUS "Performing Test ${VAR} - Success")
      FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
        "Performing C++ SOURCE FILE Test ${VAR} succeded with the following output:\n"
        "${OUTPUT}\n"
        "Source file was:\n${SOURCE}\n")
    ELSE(${VAR})
      MESSAGE(STATUS "Performing Test ${VAR} - Failed")
      SET(${VAR} "" CACHE INTERNAL "Test ${VAR}")
      FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
        "Performing C++ SOURCE FILE Test ${VAR} failed with the following output:\n"
        "${OUTPUT}\n"
        "Source file was:\n${SOURCE}\n")
    ENDIF(${VAR})
  ENDIF("${VAR}" MATCHES "^${VAR}$")
ENDMACRO(CHECK_CXX_SOURCE_COMPILES)

