Modules/FindPkgConfig.cmake - third_party/cmake - Git at Google

 #.rst:
 # FindPkgConfig
 # -------------
 #
 # A `pkg-config` module for CMake.
 #
 # Finds the ``pkg-config`` executable and add the
 # :command:`pkg_check_modules` and :command:`pkg_search_module`
 # commands.
 #
 # In order to find the ``pkg-config`` executable, it uses the
 # :variable:`PKG_CONFIG_EXECUTABLE` variable or the ``PKG_CONFIG``
 # environment variable first.

 #=============================================================================
 # Copyright 2006-2014 Kitware, Inc.
 # Copyright 2014      Christoph Grüninger <foss@grueninger.de>
 # Copyright 2006      Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de>
 #
 # Distributed under the OSI-approved BSD License (the "License");
 # see accompanying file Copyright.txt for details.
 #
 # This software is distributed WITHOUT ANY WARRANTY; without even the
 # implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 # See the License for more information.
 #=============================================================================
 # (To distribute this file outside of CMake, substitute the full
 #  License text for the above reference.)

 ### Common stuff ####
 set(PKG_CONFIG_VERSION 1)

 # find pkg-config, use PKG_CONFIG if set
 if((NOT PKG_CONFIG_EXECUTABLE) AND (NOT "$ENV{PKG_CONFIG}" STREQUAL ""))
   set(PKG_CONFIG_EXECUTABLE "$ENV{PKG_CONFIG}" CACHE FILEPATH "pkg-config executable")
 endif()
 find_program(PKG_CONFIG_EXECUTABLE NAMES pkg-config DOC "pkg-config executable")
 mark_as_advanced(PKG_CONFIG_EXECUTABLE)

 if (PKG_CONFIG_EXECUTABLE)
   execute_process(COMMAND ${PKG_CONFIG_EXECUTABLE} --version
     OUTPUT_VARIABLE PKG_CONFIG_VERSION_STRING
     ERROR_QUIET
     OUTPUT_STRIP_TRAILING_WHITESPACE)
 endif ()

 include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
 find_package_handle_standard_args(PkgConfig
                                   REQUIRED_VARS PKG_CONFIG_EXECUTABLE
                                   VERSION_VAR PKG_CONFIG_VERSION_STRING)

 # This is needed because the module name is "PkgConfig" but the name of
 # this variable has always been PKG_CONFIG_FOUND so this isn't automatically
 # handled by FPHSA.
 set(PKG_CONFIG_FOUND "${PKGCONFIG_FOUND}")

 # Unsets the given variables
 macro(_pkgconfig_unset var)
   set(${var} "" CACHE INTERNAL "")
 endmacro()

 macro(_pkgconfig_set var value)
   set(${var} ${value} CACHE INTERNAL "")
 endmacro()

 # Invokes pkgconfig, cleans up the result and sets variables
 macro(_pkgconfig_invoke _pkglist _prefix _varname _regexp)
   set(_pkgconfig_invoke_result)

   execute_process(
     COMMAND ${PKG_CONFIG_EXECUTABLE} ${ARGN} ${_pkglist}
     OUTPUT_VARIABLE _pkgconfig_invoke_result
     RESULT_VARIABLE _pkgconfig_failed
     OUTPUT_STRIP_TRAILING_WHITESPACE)

   if (_pkgconfig_failed)
     set(_pkgconfig_${_varname} "")
     _pkgconfig_unset(${_prefix}_${_varname})
   else()
     string(REGEX REPLACE "[\r\n]"                  " " _pkgconfig_invoke_result "${_pkgconfig_invoke_result}")

     if (NOT ${_regexp} STREQUAL "")
       string(REGEX REPLACE "${_regexp}" " " _pkgconfig_invoke_result "${_pkgconfig_invoke_result}")
     endif()

     separate_arguments(_pkgconfig_invoke_result)

     #message(STATUS "  ${_varname} ... ${_pkgconfig_invoke_result}")
     set(_pkgconfig_${_varname} ${_pkgconfig_invoke_result})
     _pkgconfig_set(${_prefix}_${_varname} "${_pkgconfig_invoke_result}")
   endif()
 endmacro()

 #[========================================[.rst:
 .. command:: pkg_get_variable

   Retrieves the value of a variable from a package::

     pkg_get_variable(<RESULT> <MODULE> <VARIABLE>)

   For example:

   .. code-block:: cmake

     pkg_get_variable(GI_GIRDIR gobject-introspection-1.0 girdir)
 #]========================================]
 function (pkg_get_variable result pkg variable)
   _pkgconfig_invoke("${pkg}" "prefix" "result" "" "--variable=${variable}")
   set("${result}"
     "${prefix_result}"
     PARENT_SCOPE)
 endfunction ()

 # Invokes pkgconfig two times; once without '--static' and once with
 # '--static'
 macro(_pkgconfig_invoke_dyn _pkglist _prefix _varname cleanup_regexp)
   _pkgconfig_invoke("${_pkglist}" ${_prefix}        ${_varname} "${cleanup_regexp}" ${ARGN})
   _pkgconfig_invoke("${_pkglist}" ${_prefix} STATIC_${_varname} "${cleanup_regexp}" --static  ${ARGN})
 endmacro()

 # Splits given arguments into options and a package list
 macro(_pkgconfig_parse_options _result _is_req _is_silent _no_cmake_path _no_cmake_environment_path)
   set(${_is_req} 0)
   set(${_is_silent} 0)
   set(${_no_cmake_path} 0)
   set(${_no_cmake_environment_path} 0)
   if(DEFINED PKG_CONFIG_USE_CMAKE_PREFIX_PATH)
     if(NOT PKG_CONFIG_USE_CMAKE_PREFIX_PATH)
       set(${_no_cmake_path} 1)
       set(${_no_cmake_environment_path} 1)
     endif()
   elseif(CMAKE_MINIMUM_REQUIRED_VERSION VERSION_LESS 3.1)
     set(${_no_cmake_path} 1)
     set(${_no_cmake_environment_path} 1)
   endif()

   foreach(_pkg ${ARGN})
     if (_pkg STREQUAL "REQUIRED")
       set(${_is_req} 1)
     endif ()
     if (_pkg STREQUAL "QUIET")
       set(${_is_silent} 1)
     endif ()
     if (_pkg STREQUAL "NO_CMAKE_PATH")
       set(${_no_cmake_path} 1)
     endif()
     if (_pkg STREQUAL "NO_CMAKE_ENVIRONMENT_PATH")
       set(${_no_cmake_environment_path} 1)
     endif()
   endforeach()

   set(${_result} ${ARGN})
   list(REMOVE_ITEM ${_result} "REQUIRED")
   list(REMOVE_ITEM ${_result} "QUIET")
   list(REMOVE_ITEM ${_result} "NO_CMAKE_PATH")
   list(REMOVE_ITEM ${_result} "NO_CMAKE_ENVIRONMENT_PATH")
 endmacro()

 # Add the content of a variable or an environment variable to a list of
 # paths
 # Usage:
 #  - _pkgconfig_add_extra_path(_extra_paths VAR)
 #  - _pkgconfig_add_extra_path(_extra_paths ENV VAR)
 function(_pkgconfig_add_extra_path _extra_paths_var _var)
   set(_is_env 0)
   if(ARGC GREATER 2 AND _var STREQUAL "ENV")
     set(_var ${ARGV2})
     set(_is_env 1)
   endif()
   if(NOT _is_env)
     if(NOT "${${_var}}" STREQUAL "")
       list(APPEND ${_extra_paths_var} ${${_var}})
     endif()
   else()
     if(NOT "$ENV{${_var}}" STREQUAL "")
       file(TO_CMAKE_PATH "$ENV{${_var}}" _path)
       list(APPEND ${_extra_paths_var} ${_path})
       unset(_path)
     endif()
   endif()
   set(${_extra_paths_var} ${${_extra_paths_var}} PARENT_SCOPE)
 endfunction()

 ###
 macro(_pkg_check_modules_internal _is_required _is_silent _no_cmake_path _no_cmake_environment_path _prefix)
   _pkgconfig_unset(${_prefix}_FOUND)
   _pkgconfig_unset(${_prefix}_VERSION)
   _pkgconfig_unset(${_prefix}_PREFIX)
   _pkgconfig_unset(${_prefix}_INCLUDEDIR)
   _pkgconfig_unset(${_prefix}_LIBDIR)
   _pkgconfig_unset(${_prefix}_LIBS)
   _pkgconfig_unset(${_prefix}_LIBS_L)
   _pkgconfig_unset(${_prefix}_LIBS_PATHS)
   _pkgconfig_unset(${_prefix}_LIBS_OTHER)
   _pkgconfig_unset(${_prefix}_CFLAGS)
   _pkgconfig_unset(${_prefix}_CFLAGS_I)
   _pkgconfig_unset(${_prefix}_CFLAGS_OTHER)
   _pkgconfig_unset(${_prefix}_STATIC_LIBDIR)
   _pkgconfig_unset(${_prefix}_STATIC_LIBS)
   _pkgconfig_unset(${_prefix}_STATIC_LIBS_L)
   _pkgconfig_unset(${_prefix}_STATIC_LIBS_PATHS)
   _pkgconfig_unset(${_prefix}_STATIC_LIBS_OTHER)
   _pkgconfig_unset(${_prefix}_STATIC_CFLAGS)
   _pkgconfig_unset(${_prefix}_STATIC_CFLAGS_I)
   _pkgconfig_unset(${_prefix}_STATIC_CFLAGS_OTHER)

   # create a better addressable variable of the modules and calculate its size
   set(_pkg_check_modules_list ${ARGN})
   list(LENGTH _pkg_check_modules_list _pkg_check_modules_cnt)

   if(PKG_CONFIG_EXECUTABLE)
     # give out status message telling checked module
     if (NOT ${_is_silent})
       if (_pkg_check_modules_cnt EQUAL 1)
         message(STATUS "Checking for module '${_pkg_check_modules_list}'")
       else()
         message(STATUS "Checking for modules '${_pkg_check_modules_list}'")
       endif()
     endif()

     set(_pkg_check_modules_packages)
     set(_pkg_check_modules_failed)

     set(_extra_paths)

     if(NOT _no_cmake_path)
       _pkgconfig_add_extra_path(_extra_paths CMAKE_PREFIX_PATH)
       _pkgconfig_add_extra_path(_extra_paths CMAKE_FRAMEWORK_PATH)
       _pkgconfig_add_extra_path(_extra_paths CMAKE_APPBUNDLE_PATH)
     endif()

     if(NOT _no_cmake_environment_path)
       _pkgconfig_add_extra_path(_extra_paths ENV CMAKE_PREFIX_PATH)
       _pkgconfig_add_extra_path(_extra_paths ENV CMAKE_FRAMEWORK_PATH)
       _pkgconfig_add_extra_path(_extra_paths ENV CMAKE_APPBUNDLE_PATH)
     endif()

     if(NOT "${_extra_paths}" STREQUAL "")
       # Save the PKG_CONFIG_PATH environment variable, and add paths
       # from the CMAKE_PREFIX_PATH variables
       set(_pkgconfig_path_old $ENV{PKG_CONFIG_PATH})
       set(_pkgconfig_path ${_pkgconfig_path_old})
       if(NOT "${_pkgconfig_path}" STREQUAL "")
         file(TO_CMAKE_PATH "${_pkgconfig_path}" _pkgconfig_path)
       endif()

       # Create a list of the possible pkgconfig subfolder (depending on
       # the system
       set(_lib_dirs)
       if(NOT DEFINED CMAKE_SYSTEM_NAME
           OR (CMAKE_SYSTEM_NAME MATCHES "^(Linux|kFreeBSD|GNU)$"
               AND NOT CMAKE_CROSSCOMPILING))
         if(EXISTS "/etc/debian_version") # is this a debian system ?
           if(CMAKE_LIBRARY_ARCHITECTURE)
             list(APPEND _lib_dirs "lib/${CMAKE_LIBRARY_ARCHITECTURE}/pkgconfig")
           endif()
         else()
           # not debian, chech the FIND_LIBRARY_USE_LIB64_PATHS property
           get_property(uselib64 GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS)
           if(uselib64)
             list(APPEND _lib_dirs "lib64/pkgconfig")
           endif()
         endif()
       endif()
       list(APPEND _lib_dirs "lib/pkgconfig")

       # Check if directories exist and eventually append them to the
       # pkgconfig path list
       foreach(_prefix_dir ${_extra_paths})
         foreach(_lib_dir ${_lib_dirs})
           if(EXISTS "${_prefix_dir}/${_lib_dir}")
             list(APPEND _pkgconfig_path "${_prefix_dir}/${_lib_dir}")
             list(REMOVE_DUPLICATES _pkgconfig_path)
           endif()
         endforeach()
       endforeach()

       # Prepare and set the environment variable
       if(NOT "${_pkgconfig_path}" STREQUAL "")
         # remove empty values from the list
         list(REMOVE_ITEM _pkgconfig_path "")
         file(TO_NATIVE_PATH "${_pkgconfig_path}" _pkgconfig_path)
         if(UNIX)
           string(REPLACE ";" ":" _pkgconfig_path "${_pkgconfig_path}")
           string(REPLACE "\\ " " " _pkgconfig_path "${_pkgconfig_path}")
         endif()
         set(ENV{PKG_CONFIG_PATH} ${_pkgconfig_path})
       endif()

       # Unset variables
       unset(_lib_dirs)
       unset(_pkgconfig_path)
     endif()

     # iterate through module list and check whether they exist and match the required version
     foreach (_pkg_check_modules_pkg ${_pkg_check_modules_list})
       set(_pkg_check_modules_exist_query)

       # check whether version is given
       if (_pkg_check_modules_pkg MATCHES "(.*[^><])(>=|=|<=)(.*)")
         set(_pkg_check_modules_pkg_name "${CMAKE_MATCH_1}")
         set(_pkg_check_modules_pkg_op "${CMAKE_MATCH_2}")
         set(_pkg_check_modules_pkg_ver "${CMAKE_MATCH_3}")
       else()
         set(_pkg_check_modules_pkg_name "${_pkg_check_modules_pkg}")
         set(_pkg_check_modules_pkg_op)
         set(_pkg_check_modules_pkg_ver)
       endif()

       # handle the operands
       if (_pkg_check_modules_pkg_op STREQUAL ">=")
         list(APPEND _pkg_check_modules_exist_query --atleast-version)
       endif()

       if (_pkg_check_modules_pkg_op STREQUAL "=")
         list(APPEND _pkg_check_modules_exist_query --exact-version)
       endif()

       if (_pkg_check_modules_pkg_op STREQUAL "<=")
         list(APPEND _pkg_check_modules_exist_query --max-version)
       endif()

       # create the final query which is of the format:
       # * --atleast-version <version> <pkg-name>
       # * --exact-version <version> <pkg-name>
       # * --max-version <version> <pkg-name>
       # * --exists <pkg-name>
       if (_pkg_check_modules_pkg_op)
         list(APPEND _pkg_check_modules_exist_query "${_pkg_check_modules_pkg_ver}")
       else()
         list(APPEND _pkg_check_modules_exist_query --exists)
       endif()

       _pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_VERSION)
       _pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_PREFIX)
       _pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_INCLUDEDIR)
       _pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_LIBDIR)

       list(APPEND _pkg_check_modules_exist_query "${_pkg_check_modules_pkg_name}")
       list(APPEND _pkg_check_modules_packages    "${_pkg_check_modules_pkg_name}")

       # execute the query
       execute_process(
         COMMAND ${PKG_CONFIG_EXECUTABLE} ${_pkg_check_modules_exist_query}
         RESULT_VARIABLE _pkgconfig_retval)

       # evaluate result and tell failures
       if (_pkgconfig_retval)
         if(NOT ${_is_silent})
           message(STATUS "  Package '${_pkg_check_modules_pkg}' not found")
         endif()

         set(_pkg_check_modules_failed 1)
       endif()
     endforeach()

     if(_pkg_check_modules_failed)
       # fail when requested
       if (${_is_required})
         message(FATAL_ERROR "A required package was not found")
       endif ()
     else()
       # when we are here, we checked whether requested modules
       # exist. Now, go through them and set variables

       _pkgconfig_set(${_prefix}_FOUND 1)
       list(LENGTH _pkg_check_modules_packages pkg_count)

       # iterate through all modules again and set individual variables
       foreach (_pkg_check_modules_pkg ${_pkg_check_modules_packages})
         # handle case when there is only one package required
         if (pkg_count EQUAL 1)
           set(_pkg_check_prefix "${_prefix}")
         else()
           set(_pkg_check_prefix "${_prefix}_${_pkg_check_modules_pkg}")
         endif()

         _pkgconfig_invoke(${_pkg_check_modules_pkg} "${_pkg_check_prefix}" VERSION    ""   --modversion )
         pkg_get_variable("${_pkg_check_prefix}_PREFIX" ${_pkg_check_modules_pkg} "prefix")
         pkg_get_variable("${_pkg_check_prefix}_INCLUDEDIR" ${_pkg_check_modules_pkg} "includedir")
         pkg_get_variable("${_pkg_check_prefix}_LIBDIR" ${_pkg_check_modules_pkg} "libdir")

         if (NOT ${_is_silent})
           message(STATUS "  Found ${_pkg_check_modules_pkg}, version ${_pkgconfig_VERSION}")
         endif ()
       endforeach()

       # set variables which are combined for multiple modules
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LIBRARIES           "(^| )-l" --libs-only-l )
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LIBRARY_DIRS        "(^| )-L" --libs-only-L )
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LDFLAGS             ""        --libs )
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LDFLAGS_OTHER       ""        --libs-only-other )

       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" INCLUDE_DIRS        "(^| )-I" --cflags-only-I )
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" CFLAGS              ""        --cflags )
       _pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" CFLAGS_OTHER        ""        --cflags-only-other )
     endif()

     if(NOT "${_extra_paths}" STREQUAL "")
       # Restore the environment variable
       set(ENV{PKG_CONFIG_PATH} ${_pkgconfig_path})
     endif()

     unset(_extra_paths)
     unset(_pkgconfig_path_old)
   else()
     if (${_is_required})
       message(SEND_ERROR "pkg-config tool not found")
     endif ()
   endif()
 endmacro()

 ###
 ### User visible macros start here
 ###

 #[========================================[.rst:
 .. command:: pkg_check_modules

  Checks for all the given modules. ::

     pkg_check_modules(<PREFIX> [REQUIRED] [QUIET]
                       [NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
                       <MODULE> [<MODULE>]*)


  When the ``REQUIRED`` argument was set, macros will fail with an error
  when module(s) could not be found.

  When the ``QUIET`` argument is set, no status messages will be printed.

  By default, if :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` is 3.1 or
  later, or if :variable:`PKG_CONFIG_USE_CMAKE_PREFIX_PATH` is set, the
  :variable:`CMAKE_PREFIX_PATH`, :variable:`CMAKE_FRAMEWORK_PATH`, and
  :variable:`CMAKE_APPBUNDLE_PATH` cache and environment variables will
  be added to ``pkg-config`` search path.
  The ``NO_CMAKE_PATH`` and ``NO_CMAKE_ENVIRONMENT_PATH`` arguments
  disable this behavior for the cache variables and the environment
  variables, respectively.

  It sets the following variables: ::

     PKG_CONFIG_FOUND          ... if pkg-config executable was found
     PKG_CONFIG_EXECUTABLE     ... pathname of the pkg-config program
     PKG_CONFIG_VERSION_STRING ... the version of the pkg-config program found
                                   (since CMake 2.8.8)

  For the following variables two sets of values exist; first one is the
  common one and has the given PREFIX.  The second set contains flags
  which are given out when ``pkg-config`` was called with the ``--static``
  option. ::

     <XPREFIX>_FOUND          ... set to 1 if module(s) exist
     <XPREFIX>_LIBRARIES      ... only the libraries (w/o the '-l')
     <XPREFIX>_LIBRARY_DIRS   ... the paths of the libraries (w/o the '-L')
     <XPREFIX>_LDFLAGS        ... all required linker flags
     <XPREFIX>_LDFLAGS_OTHER  ... all other linker flags
     <XPREFIX>_INCLUDE_DIRS   ... the '-I' preprocessor flags (w/o the '-I')
     <XPREFIX>_CFLAGS         ... all required cflags
     <XPREFIX>_CFLAGS_OTHER   ... the other compiler flags

  ::

     <XPREFIX> = <PREFIX>        for common case
     <XPREFIX> = <PREFIX>_STATIC for static linking

  There are some special variables whose prefix depends on the count of
  given modules.  When there is only one module, <PREFIX> stays
  unchanged.  When there are multiple modules, the prefix will be
  changed to <PREFIX>_<MODNAME>: ::

     <XPREFIX>_VERSION    ... version of the module
     <XPREFIX>_PREFIX     ... prefix-directory of the module
     <XPREFIX>_INCLUDEDIR ... include-dir of the module
     <XPREFIX>_LIBDIR     ... lib-dir of the module

  ::

     <XPREFIX> = <PREFIX>  when |MODULES| == 1, else
     <XPREFIX> = <PREFIX>_<MODNAME>

  A <MODULE> parameter can have the following formats: ::

     {MODNAME}            ... matches any version
     {MODNAME}>={VERSION} ... at least version <VERSION> is required
     {MODNAME}={VERSION}  ... exactly version <VERSION> is required
     {MODNAME}<={VERSION} ... modules must not be newer than <VERSION>

  Examples

  .. code-block:: cmake

     pkg_check_modules (GLIB2   glib-2.0)

  .. code-block:: cmake

     pkg_check_modules (GLIB2   glib-2.0>=2.10)

  Requires at least version 2.10 of glib2 and defines e.g.
  ``GLIB2_VERSION=2.10.3``

  .. code-block:: cmake

     pkg_check_modules (FOO     glib-2.0>=2.10 gtk+-2.0)

  Requires both glib2 and gtk2, and defines e.g.
  ``FOO_glib-2.0_VERSION=2.10.3`` and ``FOO_gtk+-2.0_VERSION=2.8.20``

  .. code-block:: cmake

     pkg_check_modules (XRENDER REQUIRED xrender)

  Defines for example::

    XRENDER_LIBRARIES=Xrender;X11``
    XRENDER_STATIC_LIBRARIES=Xrender;X11;pthread;Xau;Xdmcp
 #]========================================]
 macro(pkg_check_modules _prefix _module0)
   # check cached value
   if (NOT DEFINED __pkg_config_checked_${_prefix} OR __pkg_config_checked_${_prefix} LESS ${PKG_CONFIG_VERSION} OR NOT ${_prefix}_FOUND)
     _pkgconfig_parse_options   (_pkg_modules _pkg_is_required _pkg_is_silent _no_cmake_path _no_cmake_environment_path "${_module0}" ${ARGN})
     _pkg_check_modules_internal("${_pkg_is_required}" "${_pkg_is_silent}" ${_no_cmake_path} ${_no_cmake_environment_path} "${_prefix}" ${_pkg_modules})

     _pkgconfig_set(__pkg_config_checked_${_prefix} ${PKG_CONFIG_VERSION})
   endif()
 endmacro()


 #[========================================[.rst:
 .. command:: pkg_search_module

  Same as :command:`pkg_check_modules`, but instead it checks for given
  modules and uses the first working one. ::

     pkg_search_module(<PREFIX> [REQUIRED] [QUIET]
                       [NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
                       <MODULE> [<MODULE>]*)

  Examples

  .. code-block:: cmake

     pkg_search_module (BAR     libxml-2.0 libxml2 libxml>=2)
 #]========================================]
 macro(pkg_search_module _prefix _module0)
   # check cached value
   if (NOT DEFINED __pkg_config_checked_${_prefix} OR __pkg_config_checked_${_prefix} LESS ${PKG_CONFIG_VERSION} OR NOT ${_prefix}_FOUND)
     set(_pkg_modules_found 0)
     _pkgconfig_parse_options(_pkg_modules_alt _pkg_is_required _pkg_is_silent _no_cmake_path _no_cmake_environment_path "${_module0}" ${ARGN})

     if (NOT ${_pkg_is_silent})
       message(STATUS "Checking for one of the modules '${_pkg_modules_alt}'")
     endif ()

     # iterate through all modules and stop at the first working one.
     foreach(_pkg_alt ${_pkg_modules_alt})
       if(NOT _pkg_modules_found)
         _pkg_check_modules_internal(0 1 ${_no_cmake_path} ${_no_cmake_environment_path} "${_prefix}" "${_pkg_alt}")
       endif()

       if (${_prefix}_FOUND)
         set(_pkg_modules_found 1)
       endif()
     endforeach()

     if (NOT ${_prefix}_FOUND)
       if(${_pkg_is_required})
         message(SEND_ERROR "None of the required '${_pkg_modules_alt}' found")
       endif()
     endif()

     _pkgconfig_set(__pkg_config_checked_${_prefix} ${PKG_CONFIG_VERSION})
   endif()
 endmacro()


 #[========================================[.rst:
 .. variable:: PKG_CONFIG_EXECUTABLE

  Path to the pkg-config executable.


 .. variable:: PKG_CONFIG_USE_CMAKE_PREFIX_PATH

  Whether :command:`pkg_check_modules` and :command:`pkg_search_module`
  should add the paths in :variable:`CMAKE_PREFIX_PATH`,
  :variable:`CMAKE_FRAMEWORK_PATH`, and :variable:`CMAKE_APPBUNDLE_PATH`
  cache and environment variables to ``pkg-config`` search path.

  If this variable is not set, this behavior is enabled by default if
  :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` is 3.1 or later, disabled
  otherwise.
 #]========================================]


 ### Local Variables:
 ### mode: cmake
 ### End:
	#.rst:
	# FindPkgConfig
	# -------------
	#
	# A `pkg-config` module for CMake.
	#
	# Finds the ``pkg-config`` executable and add the
	# :command:`pkg_check_modules` and :command:`pkg_search_module`
	# commands.
	#
	# In order to find the ``pkg-config`` executable, it uses the
	# :variable:`PKG_CONFIG_EXECUTABLE` variable or the ``PKG_CONFIG``
	# environment variable first.

	#=============================================================================
	# Copyright 2006-2014 Kitware, Inc.
	# Copyright 2014 Christoph Grüninger <foss@grueninger.de>
	# Copyright 2006 Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de>
	#
	# Distributed under the OSI-approved BSD License (the "License");
	# see accompanying file Copyright.txt for details.
	#
	# This software is distributed WITHOUT ANY WARRANTY; without even the
	# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	# See the License for more information.
	#=============================================================================
	# (To distribute this file outside of CMake, substitute the full
	# License text for the above reference.)

	### Common stuff ####
	set(PKG_CONFIG_VERSION 1)

	# find pkg-config, use PKG_CONFIG if set
	if((NOT PKG_CONFIG_EXECUTABLE) AND (NOT "$ENV{PKG_CONFIG}" STREQUAL ""))
	set(PKG_CONFIG_EXECUTABLE "$ENV{PKG_CONFIG}" CACHE FILEPATH "pkg-config executable")
	endif()
	find_program(PKG_CONFIG_EXECUTABLE NAMES pkg-config DOC "pkg-config executable")
	mark_as_advanced(PKG_CONFIG_EXECUTABLE)

	if (PKG_CONFIG_EXECUTABLE)
	execute_process(COMMAND ${PKG_CONFIG_EXECUTABLE} --version
	OUTPUT_VARIABLE PKG_CONFIG_VERSION_STRING
	ERROR_QUIET
	OUTPUT_STRIP_TRAILING_WHITESPACE)
	endif ()

	include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
	find_package_handle_standard_args(PkgConfig
	REQUIRED_VARS PKG_CONFIG_EXECUTABLE
	VERSION_VAR PKG_CONFIG_VERSION_STRING)

	# This is needed because the module name is "PkgConfig" but the name of
	# this variable has always been PKG_CONFIG_FOUND so this isn't automatically
	# handled by FPHSA.
	set(PKG_CONFIG_FOUND "${PKGCONFIG_FOUND}")

	# Unsets the given variables
	macro(_pkgconfig_unset var)
	set(${var} "" CACHE INTERNAL "")
	endmacro()

	macro(_pkgconfig_set var value)
	set(${var} ${value} CACHE INTERNAL "")
	endmacro()

	# Invokes pkgconfig, cleans up the result and sets variables
	macro(_pkgconfig_invoke _pkglist _prefix _varname _regexp)
	set(_pkgconfig_invoke_result)

	execute_process(
	COMMAND ${PKG_CONFIG_EXECUTABLE} ${ARGN} ${_pkglist}
	OUTPUT_VARIABLE _pkgconfig_invoke_result
	RESULT_VARIABLE _pkgconfig_failed
	OUTPUT_STRIP_TRAILING_WHITESPACE)

	if (_pkgconfig_failed)
	set(_pkgconfig_${_varname} "")
	_pkgconfig_unset(${_prefix}_${_varname})
	else()
	string(REGEX REPLACE "[\r\n]" " " _pkgconfig_invoke_result "${_pkgconfig_invoke_result}")

	if (NOT ${_regexp} STREQUAL "")
	string(REGEX REPLACE "${_regexp}" " " _pkgconfig_invoke_result "${_pkgconfig_invoke_result}")
	endif()

	separate_arguments(_pkgconfig_invoke_result)

	#message(STATUS " ${_varname} ... ${_pkgconfig_invoke_result}")
	set(_pkgconfig_${_varname} ${_pkgconfig_invoke_result})
	_pkgconfig_set(${_prefix}_${_varname} "${_pkgconfig_invoke_result}")
	endif()
	endmacro()

	#[========================================[.rst:
	.. command:: pkg_get_variable

	Retrieves the value of a variable from a package::

	pkg_get_variable(<RESULT> <MODULE> <VARIABLE>)

	For example:

	.. code-block:: cmake

	pkg_get_variable(GI_GIRDIR gobject-introspection-1.0 girdir)
	#]========================================]
	function (pkg_get_variable result pkg variable)
	_pkgconfig_invoke("${pkg}" "prefix" "result" "" "--variable=${variable}")
	set("${result}"
	"${prefix_result}"
	PARENT_SCOPE)
	endfunction ()

	# Invokes pkgconfig two times; once without '--static' and once with
	# '--static'
	macro(_pkgconfig_invoke_dyn _pkglist _prefix _varname cleanup_regexp)
	_pkgconfig_invoke("${_pkglist}" ${_prefix} ${_varname} "${cleanup_regexp}" ${ARGN})
	_pkgconfig_invoke("${_pkglist}" ${_prefix} STATIC_${_varname} "${cleanup_regexp}" --static ${ARGN})
	endmacro()

	# Splits given arguments into options and a package list
	macro(_pkgconfig_parse_options _result _is_req _is_silent _no_cmake_path _no_cmake_environment_path)
	set(${_is_req} 0)
	set(${_is_silent} 0)
	set(${_no_cmake_path} 0)
	set(${_no_cmake_environment_path} 0)
	if(DEFINED PKG_CONFIG_USE_CMAKE_PREFIX_PATH)
	if(NOT PKG_CONFIG_USE_CMAKE_PREFIX_PATH)
	set(${_no_cmake_path} 1)
	set(${_no_cmake_environment_path} 1)
	endif()
	elseif(CMAKE_MINIMUM_REQUIRED_VERSION VERSION_LESS 3.1)
	set(${_no_cmake_path} 1)
	set(${_no_cmake_environment_path} 1)
	endif()

	foreach(_pkg ${ARGN})
	if (_pkg STREQUAL "REQUIRED")
	set(${_is_req} 1)
	endif ()
	if (_pkg STREQUAL "QUIET")
	set(${_is_silent} 1)
	endif ()
	if (_pkg STREQUAL "NO_CMAKE_PATH")
	set(${_no_cmake_path} 1)
	endif()
	if (_pkg STREQUAL "NO_CMAKE_ENVIRONMENT_PATH")
	set(${_no_cmake_environment_path} 1)
	endif()
	endforeach()

	set(${_result} ${ARGN})
	list(REMOVE_ITEM ${_result} "REQUIRED")
	list(REMOVE_ITEM ${_result} "QUIET")
	list(REMOVE_ITEM ${_result} "NO_CMAKE_PATH")
	list(REMOVE_ITEM ${_result} "NO_CMAKE_ENVIRONMENT_PATH")
	endmacro()

	# Add the content of a variable or an environment variable to a list of
	# paths
	# Usage:
	# - _pkgconfig_add_extra_path(_extra_paths VAR)
	# - _pkgconfig_add_extra_path(_extra_paths ENV VAR)
	function(_pkgconfig_add_extra_path _extra_paths_var _var)
	set(_is_env 0)
	if(ARGC GREATER 2 AND _var STREQUAL "ENV")
	set(_var ${ARGV2})
	set(_is_env 1)
	endif()
	if(NOT _is_env)
	if(NOT "${${_var}}" STREQUAL "")
	list(APPEND ${_extra_paths_var} ${${_var}})
	endif()
	else()
	if(NOT "$ENV{${_var}}" STREQUAL "")
	file(TO_CMAKE_PATH "$ENV{${_var}}" _path)
	list(APPEND ${_extra_paths_var} ${_path})
	unset(_path)
	endif()
	endif()
	set(${_extra_paths_var} ${${_extra_paths_var}} PARENT_SCOPE)
	endfunction()

	###
	macro(_pkg_check_modules_internal _is_required _is_silent _no_cmake_path _no_cmake_environment_path _prefix)
	_pkgconfig_unset(${_prefix}_FOUND)
	_pkgconfig_unset(${_prefix}_VERSION)
	_pkgconfig_unset(${_prefix}_PREFIX)
	_pkgconfig_unset(${_prefix}_INCLUDEDIR)
	_pkgconfig_unset(${_prefix}_LIBDIR)
	_pkgconfig_unset(${_prefix}_LIBS)
	_pkgconfig_unset(${_prefix}_LIBS_L)
	_pkgconfig_unset(${_prefix}_LIBS_PATHS)
	_pkgconfig_unset(${_prefix}_LIBS_OTHER)
	_pkgconfig_unset(${_prefix}_CFLAGS)
	_pkgconfig_unset(${_prefix}_CFLAGS_I)
	_pkgconfig_unset(${_prefix}_CFLAGS_OTHER)
	_pkgconfig_unset(${_prefix}_STATIC_LIBDIR)
	_pkgconfig_unset(${_prefix}_STATIC_LIBS)
	_pkgconfig_unset(${_prefix}_STATIC_LIBS_L)
	_pkgconfig_unset(${_prefix}_STATIC_LIBS_PATHS)
	_pkgconfig_unset(${_prefix}_STATIC_LIBS_OTHER)
	_pkgconfig_unset(${_prefix}_STATIC_CFLAGS)
	_pkgconfig_unset(${_prefix}_STATIC_CFLAGS_I)
	_pkgconfig_unset(${_prefix}_STATIC_CFLAGS_OTHER)

	# create a better addressable variable of the modules and calculate its size
	set(_pkg_check_modules_list ${ARGN})
	list(LENGTH _pkg_check_modules_list _pkg_check_modules_cnt)

	if(PKG_CONFIG_EXECUTABLE)
	# give out status message telling checked module
	if (NOT ${_is_silent})
	if (_pkg_check_modules_cnt EQUAL 1)
	message(STATUS "Checking for module '${_pkg_check_modules_list}'")
	else()
	message(STATUS "Checking for modules '${_pkg_check_modules_list}'")
	endif()
	endif()

	set(_pkg_check_modules_packages)
	set(_pkg_check_modules_failed)

	set(_extra_paths)

	if(NOT _no_cmake_path)
	_pkgconfig_add_extra_path(_extra_paths CMAKE_PREFIX_PATH)
	_pkgconfig_add_extra_path(_extra_paths CMAKE_FRAMEWORK_PATH)
	_pkgconfig_add_extra_path(_extra_paths CMAKE_APPBUNDLE_PATH)
	endif()

	if(NOT _no_cmake_environment_path)
	_pkgconfig_add_extra_path(_extra_paths ENV CMAKE_PREFIX_PATH)
	_pkgconfig_add_extra_path(_extra_paths ENV CMAKE_FRAMEWORK_PATH)
	_pkgconfig_add_extra_path(_extra_paths ENV CMAKE_APPBUNDLE_PATH)
	endif()

	if(NOT "${_extra_paths}" STREQUAL "")
	# Save the PKG_CONFIG_PATH environment variable, and add paths
	# from the CMAKE_PREFIX_PATH variables
	set(_pkgconfig_path_old $ENV{PKG_CONFIG_PATH})
	set(_pkgconfig_path ${_pkgconfig_path_old})
	if(NOT "${_pkgconfig_path}" STREQUAL "")
	file(TO_CMAKE_PATH "${_pkgconfig_path}" _pkgconfig_path)
	endif()

	# Create a list of the possible pkgconfig subfolder (depending on
	# the system
	set(_lib_dirs)
	if(NOT DEFINED CMAKE_SYSTEM_NAME
	OR (CMAKE_SYSTEM_NAME MATCHES "^(Linux\|kFreeBSD\|GNU)$"
	AND NOT CMAKE_CROSSCOMPILING))
	if(EXISTS "/etc/debian_version") # is this a debian system ?
	if(CMAKE_LIBRARY_ARCHITECTURE)
	list(APPEND _lib_dirs "lib/${CMAKE_LIBRARY_ARCHITECTURE}/pkgconfig")
	endif()
	else()
	# not debian, chech the FIND_LIBRARY_USE_LIB64_PATHS property
	get_property(uselib64 GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS)
	if(uselib64)
	list(APPEND _lib_dirs "lib64/pkgconfig")
	endif()
	endif()
	endif()
	list(APPEND _lib_dirs "lib/pkgconfig")

	# Check if directories exist and eventually append them to the
	# pkgconfig path list
	foreach(_prefix_dir ${_extra_paths})
	foreach(_lib_dir ${_lib_dirs})
	if(EXISTS "${_prefix_dir}/${_lib_dir}")
	list(APPEND _pkgconfig_path "${_prefix_dir}/${_lib_dir}")
	list(REMOVE_DUPLICATES _pkgconfig_path)
	endif()
	endforeach()
	endforeach()

	# Prepare and set the environment variable
	if(NOT "${_pkgconfig_path}" STREQUAL "")
	# remove empty values from the list
	list(REMOVE_ITEM _pkgconfig_path "")
	file(TO_NATIVE_PATH "${_pkgconfig_path}" _pkgconfig_path)
	if(UNIX)
	string(REPLACE ";" ":" _pkgconfig_path "${_pkgconfig_path}")
	string(REPLACE "\\ " " " _pkgconfig_path "${_pkgconfig_path}")
	endif()
	set(ENV{PKG_CONFIG_PATH} ${_pkgconfig_path})
	endif()

	# Unset variables
	unset(_lib_dirs)
	unset(_pkgconfig_path)
	endif()

	# iterate through module list and check whether they exist and match the required version
	foreach (_pkg_check_modules_pkg ${_pkg_check_modules_list})
	set(_pkg_check_modules_exist_query)

	# check whether version is given
	if (_pkg_check_modules_pkg MATCHES "(.[^><])(>=\|=\|<=)(.)")
	set(_pkg_check_modules_pkg_name "${CMAKE_MATCH_1}")
	set(_pkg_check_modules_pkg_op "${CMAKE_MATCH_2}")
	set(_pkg_check_modules_pkg_ver "${CMAKE_MATCH_3}")
	else()
	set(_pkg_check_modules_pkg_name "${_pkg_check_modules_pkg}")
	set(_pkg_check_modules_pkg_op)
	set(_pkg_check_modules_pkg_ver)
	endif()

	# handle the operands
	if (_pkg_check_modules_pkg_op STREQUAL ">=")
	list(APPEND _pkg_check_modules_exist_query --atleast-version)
	endif()

	if (_pkg_check_modules_pkg_op STREQUAL "=")
	list(APPEND _pkg_check_modules_exist_query --exact-version)
	endif()

	if (_pkg_check_modules_pkg_op STREQUAL "<=")
	list(APPEND _pkg_check_modules_exist_query --max-version)
	endif()

	# create the final query which is of the format:
	# * --atleast-version <version> <pkg-name>
	# * --exact-version <version> <pkg-name>
	# * --max-version <version> <pkg-name>
	# * --exists <pkg-name>
	if (_pkg_check_modules_pkg_op)
	list(APPEND _pkg_check_modules_exist_query "${_pkg_check_modules_pkg_ver}")
	else()
	list(APPEND _pkg_check_modules_exist_query --exists)
	endif()

	_pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_VERSION)
	_pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_PREFIX)
	_pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_INCLUDEDIR)
	_pkgconfig_unset(${_prefix}_${_pkg_check_modules_pkg_name}_LIBDIR)

	list(APPEND _pkg_check_modules_exist_query "${_pkg_check_modules_pkg_name}")
	list(APPEND _pkg_check_modules_packages "${_pkg_check_modules_pkg_name}")

	# execute the query
	execute_process(
	COMMAND ${PKG_CONFIG_EXECUTABLE} ${_pkg_check_modules_exist_query}
	RESULT_VARIABLE _pkgconfig_retval)

	# evaluate result and tell failures
	if (_pkgconfig_retval)
	if(NOT ${_is_silent})
	message(STATUS " Package '${_pkg_check_modules_pkg}' not found")
	endif()

	set(_pkg_check_modules_failed 1)
	endif()
	endforeach()

	if(_pkg_check_modules_failed)
	# fail when requested
	if (${_is_required})
	message(FATAL_ERROR "A required package was not found")
	endif ()
	else()
	# when we are here, we checked whether requested modules
	# exist. Now, go through them and set variables

	_pkgconfig_set(${_prefix}_FOUND 1)
	list(LENGTH _pkg_check_modules_packages pkg_count)

	# iterate through all modules again and set individual variables
	foreach (_pkg_check_modules_pkg ${_pkg_check_modules_packages})
	# handle case when there is only one package required
	if (pkg_count EQUAL 1)
	set(_pkg_check_prefix "${_prefix}")
	else()
	set(_pkg_check_prefix "${_prefix}_${_pkg_check_modules_pkg}")
	endif()

	_pkgconfig_invoke(${_pkg_check_modules_pkg} "${_pkg_check_prefix}" VERSION "" --modversion )
	pkg_get_variable("${_pkg_check_prefix}_PREFIX" ${_pkg_check_modules_pkg} "prefix")
	pkg_get_variable("${_pkg_check_prefix}_INCLUDEDIR" ${_pkg_check_modules_pkg} "includedir")
	pkg_get_variable("${_pkg_check_prefix}_LIBDIR" ${_pkg_check_modules_pkg} "libdir")

	if (NOT ${_is_silent})
	message(STATUS " Found ${_pkg_check_modules_pkg}, version ${_pkgconfig_VERSION}")
	endif ()
	endforeach()

	# set variables which are combined for multiple modules
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LIBRARIES "(^\| )-l" --libs-only-l )
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LIBRARY_DIRS "(^\| )-L" --libs-only-L )
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LDFLAGS "" --libs )
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" LDFLAGS_OTHER "" --libs-only-other )

	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" INCLUDE_DIRS "(^\| )-I" --cflags-only-I )
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" CFLAGS "" --cflags )
	_pkgconfig_invoke_dyn("${_pkg_check_modules_packages}" "${_prefix}" CFLAGS_OTHER "" --cflags-only-other )
	endif()

	if(NOT "${_extra_paths}" STREQUAL "")
	# Restore the environment variable
	set(ENV{PKG_CONFIG_PATH} ${_pkgconfig_path})
	endif()

	unset(_extra_paths)
	unset(_pkgconfig_path_old)
	else()
	if (${_is_required})
	message(SEND_ERROR "pkg-config tool not found")
	endif ()
	endif()
	endmacro()

	###
	### User visible macros start here
	###

	#[========================================[.rst:
	.. command:: pkg_check_modules

	Checks for all the given modules. ::

	pkg_check_modules(<PREFIX> [REQUIRED] [QUIET]
	[NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
	<MODULE> [<MODULE>]*)


	When the ``REQUIRED`` argument was set, macros will fail with an error
	when module(s) could not be found.

	When the ``QUIET`` argument is set, no status messages will be printed.

	By default, if :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` is 3.1 or
	later, or if :variable:`PKG_CONFIG_USE_CMAKE_PREFIX_PATH` is set, the
	:variable:`CMAKE_PREFIX_PATH`, :variable:`CMAKE_FRAMEWORK_PATH`, and
	:variable:`CMAKE_APPBUNDLE_PATH` cache and environment variables will
	be added to ``pkg-config`` search path.
	The ``NO_CMAKE_PATH`` and ``NO_CMAKE_ENVIRONMENT_PATH`` arguments
	disable this behavior for the cache variables and the environment
	variables, respectively.

	It sets the following variables: ::

	PKG_CONFIG_FOUND ... if pkg-config executable was found
	PKG_CONFIG_EXECUTABLE ... pathname of the pkg-config program
	PKG_CONFIG_VERSION_STRING ... the version of the pkg-config program found
	(since CMake 2.8.8)

	For the following variables two sets of values exist; first one is the
	common one and has the given PREFIX. The second set contains flags
	which are given out when ``pkg-config`` was called with the ``--static``
	option. ::

	<XPREFIX>_FOUND ... set to 1 if module(s) exist
	<XPREFIX>_LIBRARIES ... only the libraries (w/o the '-l')
	<XPREFIX>_LIBRARY_DIRS ... the paths of the libraries (w/o the '-L')
	<XPREFIX>_LDFLAGS ... all required linker flags
	<XPREFIX>_LDFLAGS_OTHER ... all other linker flags
	<XPREFIX>_INCLUDE_DIRS ... the '-I' preprocessor flags (w/o the '-I')
	<XPREFIX>_CFLAGS ... all required cflags
	<XPREFIX>_CFLAGS_OTHER ... the other compiler flags

	::

	<XPREFIX> = <PREFIX> for common case
	<XPREFIX> = <PREFIX>_STATIC for static linking

	There are some special variables whose prefix depends on the count of
	given modules. When there is only one module, <PREFIX> stays
	unchanged. When there are multiple modules, the prefix will be
	changed to <PREFIX>_<MODNAME>: ::

	<XPREFIX>_VERSION ... version of the module
	<XPREFIX>_PREFIX ... prefix-directory of the module
	<XPREFIX>_INCLUDEDIR ... include-dir of the module
	<XPREFIX>_LIBDIR ... lib-dir of the module

	::

	<XPREFIX> = <PREFIX> when \|MODULES\| == 1, else
	<XPREFIX> = <PREFIX>_<MODNAME>

	A <MODULE> parameter can have the following formats: ::

	{MODNAME} ... matches any version
	{MODNAME}>={VERSION} ... at least version <VERSION> is required
	{MODNAME}={VERSION} ... exactly version <VERSION> is required
	{MODNAME}<={VERSION} ... modules must not be newer than <VERSION>

	Examples

	.. code-block:: cmake

	pkg_check_modules (GLIB2 glib-2.0)

	.. code-block:: cmake

	pkg_check_modules (GLIB2 glib-2.0>=2.10)

	Requires at least version 2.10 of glib2 and defines e.g.
	``GLIB2_VERSION=2.10.3``

	.. code-block:: cmake

	pkg_check_modules (FOO glib-2.0>=2.10 gtk+-2.0)

	Requires both glib2 and gtk2, and defines e.g.
	``FOO_glib-2.0_VERSION=2.10.3`` and ``FOO_gtk+-2.0_VERSION=2.8.20``

	.. code-block:: cmake

	pkg_check_modules (XRENDER REQUIRED xrender)

	Defines for example::

	XRENDER_LIBRARIES=Xrender;X11``
	XRENDER_STATIC_LIBRARIES=Xrender;X11;pthread;Xau;Xdmcp
	#]========================================]
	macro(pkg_check_modules _prefix _module0)
	# check cached value
	if (NOT DEFINED __pkg_config_checked_${_prefix} OR __pkg_config_checked_${_prefix} LESS ${PKG_CONFIG_VERSION} OR NOT ${_prefix}_FOUND)
	_pkgconfig_parse_options (_pkg_modules _pkg_is_required _pkg_is_silent _no_cmake_path _no_cmake_environment_path "${_module0}" ${ARGN})
	_pkg_check_modules_internal("${_pkg_is_required}" "${_pkg_is_silent}" ${_no_cmake_path} ${_no_cmake_environment_path} "${_prefix}" ${_pkg_modules})

	_pkgconfig_set(__pkg_config_checked_${_prefix} ${PKG_CONFIG_VERSION})
	endif()
	endmacro()


	#[========================================[.rst:
	.. command:: pkg_search_module

	Same as :command:`pkg_check_modules`, but instead it checks for given
	modules and uses the first working one. ::

	pkg_search_module(<PREFIX> [REQUIRED] [QUIET]
	[NO_CMAKE_PATH] [NO_CMAKE_ENVIRONMENT_PATH]
	<MODULE> [<MODULE>]*)

	Examples

	.. code-block:: cmake

	pkg_search_module (BAR libxml-2.0 libxml2 libxml>=2)
	#]========================================]
	macro(pkg_search_module _prefix _module0)
	# check cached value
	if (NOT DEFINED __pkg_config_checked_${_prefix} OR __pkg_config_checked_${_prefix} LESS ${PKG_CONFIG_VERSION} OR NOT ${_prefix}_FOUND)
	set(_pkg_modules_found 0)
	_pkgconfig_parse_options(_pkg_modules_alt _pkg_is_required _pkg_is_silent _no_cmake_path _no_cmake_environment_path "${_module0}" ${ARGN})

	if (NOT ${_pkg_is_silent})
	message(STATUS "Checking for one of the modules '${_pkg_modules_alt}'")
	endif ()

	# iterate through all modules and stop at the first working one.
	foreach(_pkg_alt ${_pkg_modules_alt})
	if(NOT _pkg_modules_found)
	_pkg_check_modules_internal(0 1 ${_no_cmake_path} ${_no_cmake_environment_path} "${_prefix}" "${_pkg_alt}")
	endif()

	if (${_prefix}_FOUND)
	set(_pkg_modules_found 1)
	endif()
	endforeach()

	if (NOT ${_prefix}_FOUND)
	if(${_pkg_is_required})
	message(SEND_ERROR "None of the required '${_pkg_modules_alt}' found")
	endif()
	endif()

	_pkgconfig_set(__pkg_config_checked_${_prefix} ${PKG_CONFIG_VERSION})
	endif()
	endmacro()


	#[========================================[.rst:
	.. variable:: PKG_CONFIG_EXECUTABLE

	Path to the pkg-config executable.


	.. variable:: PKG_CONFIG_USE_CMAKE_PREFIX_PATH

	Whether :command:`pkg_check_modules` and :command:`pkg_search_module`
	should add the paths in :variable:`CMAKE_PREFIX_PATH`,
	:variable:`CMAKE_FRAMEWORK_PATH`, and :variable:`CMAKE_APPBUNDLE_PATH`
	cache and environment variables to ``pkg-config`` search path.

	If this variable is not set, this behavior is enabled by default if
	:variable:`CMAKE_MINIMUM_REQUIRED_VERSION` is 3.1 or later, disabled
	otherwise.
	#]========================================]


	### Local Variables:
	### mode: cmake
	### End: