Modules/CheckVariableExists.cmake

   1 #
   2 # Check if the variable exists.
   3 # # CHECK_VARIABLE_EXISTS - macro which checks if the variable exists
   4 # VAR - the name of the variable
   5 # VARIABLE - variable to store the result
   6 #
   7
   8 MACRO(CHECK_VARIABLE_EXISTS VAR VARIABLE)
   9   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
  10     SET(MACRO_CHECK_VARIABLE_DEFINITIONS
  11       "-DCHECK_VARIABLE_EXISTS=${VAR} ${CMAKE_REQUIRED_FLAGS}")
  12     MESSAGE(STATUS "Looking for ${VAR}")
  13     IF(CMAKE_REQUIRED_LIBRARIES)
  14       SET(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES
  15         "-DLINK_LIBRARIES:STRING=${CMAKE_REQUIRED_LIBRARIES}")
  16     ENDIF(CMAKE_REQUIRED_LIBRARIES)
  17     TRY_COMPILE(${VARIABLE}
  18       ${CMAKE_BINARY_DIR}
  19       ${CMAKE_ROOT}/Modules/CheckVariableExists.c
  20       CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_VARIABLE_DEFINITIONS}
  21       "${CHECK_VARIABLE_EXISTS_ADD_LIBRARIES}"
  22       OUTPUT_VARIABLE OUTPUT)
  23     IF(${VARIABLE})
  24       SET(${VARIABLE} 1 CACHE INTERNAL "Have variable ${VAR}")
  25       MESSAGE(STATUS "Looking for ${VAR} - found")
  26       FILE(APPEND ${CMAKE_BINARY_DIR}/CMakeOutput.log
  27         "Determining if the variable ${VAR} exists passed with the following output:\n"
  28         "${OUTPUT}\n\n")
  29     ELSE(${VARIABLE})
  30       SET(${VARIABLE} "" CACHE INTERNAL "Have variable ${VAR}")
  31       MESSAGE(STATUS "Looking for ${VAR} - not found")
  32       FILE(APPEND ${CMAKE_BINARY_DIR}/CMakeError.log
  33         "Determining if the variable ${VAR} exists failed with the following output:\n"
  34         "${OUTPUT}\n\n")
  35     ENDIF(${VARIABLE})
  36   ENDIF("${VARIABLE}" MATCHES "^${VARIABLE}$")
  37 ENDMACRO(CHECK_VARIABLE_EXISTS)