# - Check if the source code provided in the SOURCE argument compiles and runs.
# CHECK_CXX_SOURCE_RUNS(SOURCE VAR)
# - macro which checks if the source code compiles
#  SOURCE - source code to try to compile
#  VAR    - variable to store the result, 1 for success, empty for failure
#
# 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_RUNS SOURCE VAR)
  IF("${VAR}" MATCHES "^${VAR}$")
    SET(MACRO_CHECK_FUNCTION_DEFINITIONS 
      "-D${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 ${VAR}")
    TRY_RUN(${VAR}_EXITCODE ${VAR}_COMPILED
      ${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}
      -DCMAKE_SKIP_RPATH:BOOL=${CMAKE_SKIP_RPATH}
      "${CHECK_CXX_SOURCE_COMPILES_ADD_LIBRARIES}"
      "${CHECK_CXX_SOURCE_COMPILES_ADD_INCLUDES}"
      COMPILE_OUTPUT_VARIABLE OUTPUT)

    # if it did not compile make the return value fail code of 1
    IF(NOT ${VAR}_COMPILED)
      SET(${VAR}_EXITCODE 1)
    ENDIF(NOT ${VAR}_COMPILED)
    # if the return value was 0 then it worked
    IF("${${VAR}_EXITCODE}" EQUAL 0)
      SET(${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" 
        "Return value: ${${VAR}}\n"
        "Source file was:\n${SOURCE}\n")
    ELSE("${${VAR}_EXITCODE}" EQUAL 0)
      IF(CMAKE_CROSSCOMPILING AND "${${VAR}_EXITCODE}" MATCHES  "FAILED_TO_RUN")
        SET(${VAR} "${${VAR}_EXITCODE}")
      ELSE(CMAKE_CROSSCOMPILING AND "${${VAR}_EXITCODE}" MATCHES  "FAILED_TO_RUN")
        SET(${VAR} "" CACHE INTERNAL "Test ${VAR}")
      ENDIF(CMAKE_CROSSCOMPILING AND "${${VAR}_EXITCODE}" MATCHES  "FAILED_TO_RUN")

      MESSAGE(STATUS "Performing Test ${VAR} - Failed")
      FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log 
        "Performing C++ SOURCE FILE Test ${VAR} failed with the following output:\n"
        "${OUTPUT}\n"  
        "Return value: ${${VAR}_EXITCODE}\n"
        "Source file was:\n${SOURCE}\n")
    ENDIF("${${VAR}_EXITCODE}" EQUAL 0)
  ENDIF("${VAR}" MATCHES "^${VAR}$")
ENDMACRO(CHECK_CXX_SOURCE_RUNS)