#
# Check if the function exists.
#
# CHECK_LIBRARY_EXISTS - macro which checks if the function exists
# FUNCTION - the name of the function
# VARIABLE - variable to store the result
#

MACRO(CHECK_LIBRARY_EXISTS LIBRARY FUNCTION LOCATION VARIABLE)
  SET(MACRO_CHECK_LIBRARY_EXISTS_DEFINITION -DCHECK_FUNCTION_EXISTS=${FUNCTION})

  TRY_COMPILE(${VARIABLE}
             ${PROJECT_BINARY_DIR}
             ${CMAKE_ROOT}/Modules/CheckFunctionExists.c
             CMAKE_FLAGS 
               -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_LIBRARY_EXISTS_DEFINITION}
               -DLINK_DIRECTORIES:STRING=${LOCATION}
               -DLINK_LIBRARIES:STRING=${LIBRARY}
             OUTPUT_VARIABLE OUTPUT)

  IF(${VARIABLE})
    SET(${VARIABLE} 1 CACHE INTERNAL "Have library ${LIBRARY}")
  ELSE(${VARIABLE})
    SET(${VARIABLE} "" CACHE INTERNAL "Have library ${LIBRARY}")
    WRITE_FILE(${PROJECT_BINARY_DIR}/CMakeError.log 
      "Determining if the function ${FUNCTION} exists in the ${LIBRARY} failed with the following output:\n"
      "${OUTPUT}\n")
  ENDIF(${VARIABLE})
ENDMACRO(CHECK_LIBRARY_EXISTS)