#
# Check if the symbol exists in include files
#
# CHECK_SYMBOL_EXISTS - macro which checks the symbol exists in include files.
# SYMBOL - symbol
# FILES  - include files to check
# VARIABLE - variable to return result
#

MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
  IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
    SET(CHECK_SYMBOL_EXISTS_CONTENT "/* */\n")
    SET(MACRO_CHECK_SYMBOL_EXISTS_FLAGS ${CMAKE_REQUIRED_FLAGS})
    STRING(ASCII 35 POUND)
    STRING(ASCII 40 OPEN_PARENT)
    STRING(ASCII 41 CLOSE_PARENT)
    SET(PARENTS "${OPEN_PARENT}${CLOSE_PARENT}")
    IF(CMAKE_REQUIRED_LIBRARIES)
      SET(CHECK_SYMBOL_EXISTS_LIBS 
        "-DLINK_LIBRARIES:STRING=${CMAKE_REQUIRED_LIBRARIES}")
    ENDIF(CMAKE_REQUIRED_LIBRARIES)
    FOREACH(FILE ${FILES})
      SET(CHECK_SYMBOL_EXISTS_CONTENT
            "${CHECK_SYMBOL_EXISTS_CONTENT}${POUND}include <${FILE}>\n")
    ENDFOREACH(FILE)
    SET(CHECK_SYMBOL_EXISTS_CONTENT
      "${CHECK_SYMBOL_EXISTS_CONTENT}\nvoid cmakeRequireSymbol${OPEN_PARENT}int dummy,...${CLOSE_PARENT}{${OPEN_PARENT}void${CLOSE_PARENT}dummy;}\nint main${PARENTS}\n{\n${POUND}ifndef ${SYMBOL}\n  cmakeRequireSymbol${OPEN_PARENT}0,&${SYMBOL}${CLOSE_PARENT};\n${POUND}endif\n  return 0;\n}\n")

    WRITE_FILE(${CMAKE_BINARY_DIR}/CMakeTmp/CheckSymbolExists.c 
               "${CHECK_SYMBOL_EXISTS_CONTENT}")
    
    MESSAGE(STATUS "Looking for ${SYMBOL}")
    TRY_COMPILE(${VARIABLE}
               ${CMAKE_BINARY_DIR}
               ${CMAKE_BINARY_DIR}/CMakeTmp/CheckSymbolExists.c
               CMAKE_FLAGS 
                -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_SYMBOL_EXISTS_FLAGS}
               "${CHECK_SYMBOL_EXISTS_LIBS}"
               OUTPUT_VARIABLE OUTPUT)
    IF(${VARIABLE})
      MESSAGE(STATUS "Looking for ${SYMBOL} - found")
      SET(${VARIABLE} 1 CACHE INTERNAL "Have symbol ${SYMBOL}")
      WRITE_FILE(${CMAKE_BINARY_DIR}/CMakeOutput.log 
        "Determining if the ${SYMBOL} "
        "exist passed with the following output:\n"
        "${OUTPUT}\nFile ${CMAKE_BINARY_DIR}/CMakeTmp/CheckSymbolExists.c:\n"
        "${CHECK_SYMBOL_EXISTS_CONTENT}" APPEND)
    ELSE(${VARIABLE})
      MESSAGE(STATUS "Looking for ${SYMBOL} - not found.")
      SET(${VARIABLE} "" CACHE INTERNAL "Have symbol ${SYMBOL}")
      WRITE_FILE(${CMAKE_BINARY_DIR}/CMakeError.log 
        "Determining if the ${SYMBOL} "
        "exist failed with the following output:\n"
        "${OUTPUT}\nFile ${CMAKE_BINARY_DIR}/CMakeTmp/CheckSymbolExists.c:\n"
        "${CHECK_SYMBOL_EXISTS_CONTENT}" APPEND)
    ENDIF(${VARIABLE})
  ENDIF("${VARIABLE}" MATCHES "^${VARIABLE}$")
ENDMACRO(CHECK_SYMBOL_EXISTS)