# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#[=======================================================================[.rst:
CheckLibraryExists
------------------

Check if the function exists.

CHECK_LIBRARY_EXISTS (LIBRARY FUNCTION LOCATION VARIABLE)

::

  LIBRARY  - the name of the library you are looking for
  FUNCTION - the name of the function
  LOCATION - location where the library should be found
  VARIABLE - variable to store the result
             Will be created as an internal cache variable.



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_LIBRARIES = list of libraries to link
  CMAKE_REQUIRED_QUIET = execute quietly without messages
#]=======================================================================]

include_guard(GLOBAL)

macro(CHECK_LIBRARY_EXISTS LIBRARY FUNCTION LOCATION VARIABLE)
  if(NOT DEFINED "${VARIABLE}")
    set(MACRO_CHECK_LIBRARY_EXISTS_DEFINITION
      "-DCHECK_FUNCTION_EXISTS=${FUNCTION} ${CMAKE_REQUIRED_FLAGS}")
    if(NOT CMAKE_REQUIRED_QUIET)
      message(STATUS "Looking for ${FUNCTION} in ${LIBRARY}")
    endif()
    set(CHECK_LIBRARY_EXISTS_LIBRARIES ${LIBRARY})
    if(CMAKE_REQUIRED_LIBRARIES)
      set(CHECK_LIBRARY_EXISTS_LIBRARIES
        ${CHECK_LIBRARY_EXISTS_LIBRARIES} ${CMAKE_REQUIRED_LIBRARIES})
    endif()

    if(CMAKE_C_COMPILER_LOADED)
      set(_cle_source ${CMAKE_ROOT}/Modules/CheckFunctionExists.c)
    elseif(CMAKE_CXX_COMPILER_LOADED)
      set(_cle_source ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CheckLibraryExists/CheckFunctionExists.cxx)
      configure_file(${CMAKE_ROOT}/Modules/CheckFunctionExists.c "${_cle_source}" COPYONLY)
    else()
      message(FATAL_ERROR "CHECK_FUNCTION_EXISTS needs either C or CXX language enabled")
    endif()

    try_compile(${VARIABLE}
      ${CMAKE_BINARY_DIR}
      ${_cle_source}
      COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
      LINK_LIBRARIES ${CHECK_LIBRARY_EXISTS_LIBRARIES}
      CMAKE_FLAGS
      -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_LIBRARY_EXISTS_DEFINITION}
      -DLINK_DIRECTORIES:STRING=${LOCATION}
      OUTPUT_VARIABLE OUTPUT)
    unset(_cle_source)

    if(${VARIABLE})
      if(NOT CMAKE_REQUIRED_QUIET)
        message(STATUS "Looking for ${FUNCTION} in ${LIBRARY} - found")
      endif()
      set(${VARIABLE} 1 CACHE INTERNAL "Have library ${LIBRARY}")
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
        "Determining if the function ${FUNCTION} exists in the ${LIBRARY} "
        "passed with the following output:\n"
        "${OUTPUT}\n\n")
    else()
      if(NOT CMAKE_REQUIRED_QUIET)
        message(STATUS "Looking for ${FUNCTION} in ${LIBRARY} - not found")
      endif()
      set(${VARIABLE} "" CACHE INTERNAL "Have library ${LIBRARY}")
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
        "Determining if the function ${FUNCTION} exists in the ${LIBRARY} "
        "failed with the following output:\n"
        "${OUTPUT}\n\n")
    endif()
  endif()
endmacro()
