cmake/FindGlog.cmake - ceres-solver - Git at Google

 # Ceres Solver - A fast non-linear least squares minimizer
 # Copyright 2023 Google Inc. All rights reserved.
 # http://ceres-solver.org/
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
 #
 # * Redistributions of source code must retain the above copyright notice,
 #   this list of conditions and the following disclaimer.
 # * Redistributions in binary form must reproduce the above copyright notice,
 #   this list of conditions and the following disclaimer in the documentation
 #   and/or other materials provided with the distribution.
 # * Neither the name of Google Inc. nor the names of its contributors may be
 #   used to endorse or promote products derived from this software without
 #   specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 #
 # Author: alexs.mac@gmail.com (Alex Stewart)
 #

 # FindGlog.cmake - Find Google glog logging library.
 #
 # This module defines the following variables:
 #
 # GLOG_FOUND: TRUE iff glog is found.
 # GLOG_INCLUDE_DIRS: Include directories for glog.
 # GLOG_LIBRARIES: Libraries required to link glog.
 # FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION: True iff the version of glog found
 #                                           was built & installed / exported
 #                                           as a CMake package.
 #
 # The following variables control the behaviour of this module:
 #
 # GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION: TRUE/FALSE, iff TRUE then
 #                           then prefer using an exported CMake configuration
 #                           generated by glog > 0.3.4 over searching for the
 #                           glog components manually.  Otherwise (FALSE)
 #                           ignore any exported glog CMake configurations and
 #                           always perform a manual search for the components.
 #                           Default: TRUE iff user does not define this variable
 #                           before we are called, and does NOT specify either
 #                           GLOG_INCLUDE_DIR_HINTS or GLOG_LIBRARY_DIR_HINTS
 #                           otherwise FALSE.
 # GLOG_INCLUDE_DIR_HINTS: List of additional directories in which to
 #                         search for glog includes, e.g: /timbuktu/include.
 # GLOG_LIBRARY_DIR_HINTS: List of additional directories in which to
 #                         search for glog libraries, e.g: /timbuktu/lib.
 #
 # The following variables are also defined by this module, but in line with
 # CMake recommended FindPackage() module style should NOT be referenced directly
 # by callers (use the plural variables detailed above instead).  These variables
 # do however affect the behaviour of the module via FIND_[PATH/LIBRARY]() which
 # are NOT re-called (i.e. search for library is not repeated) if these variables
 # are set with valid values _in the CMake cache_. This means that if these
 # variables are set directly in the cache, either by the user in the CMake GUI,
 # or by the user passing -DVAR=VALUE directives to CMake when called (which
 # explicitly defines a cache variable), then they will be used verbatim,
 # bypassing the HINTS variables and other hard-coded search locations.
 #
 # GLOG_INCLUDE_DIR: Include directory for glog, not including the
 #                   include directory of any dependencies.
 # GLOG_LIBRARY: glog library, not including the libraries of any
 #               dependencies.

 # Reset CALLERS_CMAKE_FIND_LIBRARY_PREFIXES to its value when
 # FindGlog was invoked.
 macro(GLOG_RESET_FIND_LIBRARY_PREFIX)
   if (MSVC AND CALLERS_CMAKE_FIND_LIBRARY_PREFIXES)
     set(CMAKE_FIND_LIBRARY_PREFIXES "${CALLERS_CMAKE_FIND_LIBRARY_PREFIXES}")
   endif()
 endmacro(GLOG_RESET_FIND_LIBRARY_PREFIX)

 # Called if we failed to find glog or any of it's required dependencies,
 # unsets all public (designed to be used externally) variables and reports
 # error message at priority depending upon [REQUIRED/QUIET/<NONE>] argument.
 macro(GLOG_REPORT_NOT_FOUND REASON_MSG)
   unset(GLOG_FOUND)
   unset(GLOG_INCLUDE_DIRS)
   unset(GLOG_LIBRARIES)
   # Make results of search visible in the CMake GUI if glog has not
   # been found so that user does not have to toggle to advanced view.
   mark_as_advanced(CLEAR GLOG_INCLUDE_DIR
                          GLOG_LIBRARY)

   glog_reset_find_library_prefix()

   # Note <package>_FIND_[REQUIRED/QUIETLY] variables defined by FindPackage()
   # use the camelcase library name, not uppercase.
   if (Glog_FIND_QUIETLY)
     message(STATUS "Failed to find glog - " ${REASON_MSG} ${ARGN})
   elseif (Glog_FIND_REQUIRED)
     message(FATAL_ERROR "Failed to find glog - " ${REASON_MSG} ${ARGN})
   else()
     # Neither QUIETLY nor REQUIRED, use no priority which emits a message
     # but continues configuration and allows generation.
     message("-- Failed to find glog - " ${REASON_MSG} ${ARGN})
   endif ()
   return()
 endmacro(GLOG_REPORT_NOT_FOUND)

 # glog_message([mode] "message text")
 #
 # Wraps the standard cmake 'message' command, but suppresses output
 # if the QUIET flag was passed to the find_package(Glog ...) call.
 function(GLOG_MESSAGE)
   if (NOT Glog_FIND_QUIETLY)
     message(${ARGN})
   endif()
 endfunction()

 # Protect against any alternative find_package scripts for this library having
 # been called previously (in a client project) which set GLOG_FOUND, but not
 # the other variables we require / set here which could cause the search logic
 # here to fail.
 unset(GLOG_FOUND)

 # -----------------------------------------------------------------
 # By default, if the user has expressed no preference for using an exported
 # glog CMake configuration over performing a search for the installed
 # components, and has not specified any hints for the search locations, then
 # prefer a glog exported configuration if available.
 if (NOT DEFINED GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION
     AND NOT GLOG_INCLUDE_DIR_HINTS
     AND NOT GLOG_LIBRARY_DIR_HINTS)
   glog_message(STATUS "No preference for use of exported glog CMake "
     "configuration set, and no hints for include/library directories provided. "
     "Defaulting to preferring an installed/exported glog CMake configuration "
     "if available.")
   set(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION TRUE)
 endif()

 # On macOS, add the Homebrew prefix (with appropriate suffixes) to the
 # respective HINTS directories (after any user-specified locations).  This
 # handles Homebrew installations into non-standard locations (not /usr/local).
 # We do not use CMAKE_PREFIX_PATH for this as given the search ordering of
 # find_xxx(), doing so would override any user-specified HINTS locations with
 # the Homebrew version if it exists.
 if (CMAKE_SYSTEM_NAME MATCHES "Darwin")
   find_program(HOMEBREW_EXECUTABLE brew)
   mark_as_advanced(FORCE HOMEBREW_EXECUTABLE)
   if (HOMEBREW_EXECUTABLE)
     # Detected a Homebrew install, query for its install prefix.
     execute_process(COMMAND ${HOMEBREW_EXECUTABLE} --prefix
       OUTPUT_VARIABLE HOMEBREW_INSTALL_PREFIX
       OUTPUT_STRIP_TRAILING_WHITESPACE)
     glog_message(STATUS "Detected Homebrew with install prefix: "
       "${HOMEBREW_INSTALL_PREFIX}, adding to CMake search paths.")
     list(APPEND GLOG_INCLUDE_DIR_HINTS "${HOMEBREW_INSTALL_PREFIX}/include")
     list(APPEND GLOG_LIBRARY_DIR_HINTS "${HOMEBREW_INSTALL_PREFIX}/lib")
   endif()
 endif()

 if (GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)
   # Try to find an exported CMake configuration for glog, as generated by
   # glog versions > 0.3.4
   #
   # We search twice, s/t we can invert the ordering of precedence used by
   # find_package() for exported package build directories, and installed
   # packages (found via CMAKE_SYSTEM_PREFIX_PATH), listed as items 6) and 7)
   # respectively in [1].
   #
   # By default, exported build directories are (in theory) detected first, and
   # this is usually the case on Windows.  However, on OS X & Linux, the install
   # path (/usr/local) is typically present in the PATH environment variable
   # which is checked in item 4) in [1] (i.e. before both of the above, unless
   # NO_SYSTEM_ENVIRONMENT_PATH is passed).  As such on those OSs installed
   # packages are usually detected in preference to exported package build
   # directories.
   #
   # To ensure a more consistent response across all OSs, and as users usually
   # want to prefer an installed version of a package over a locally built one
   # where both exist (esp. as the exported build directory might be removed
   # after installation), we first search with NO_CMAKE_PACKAGE_REGISTRY which
   # means any build directories exported by the user are ignored, and thus
   # installed directories are preferred.  If this fails to find the package
   # we then research again, but without NO_CMAKE_PACKAGE_REGISTRY, so any
   # exported build directories will now be detected.
   #
   # To prevent confusion on Windows, we also pass NO_CMAKE_BUILDS_PATH (which
   # is item 5) in [1]), to not preferentially use projects that were built
   # recently with the CMake GUI to ensure that we always prefer an installed
   # version if available.
   #
   # NOTE: We use the NAMES option as glog erroneously uses 'google-glog' as its
   #       project name when built with CMake, but exports itself as just 'glog'.
   #       On Linux/OS X this does not break detection as the project name is
   #       not used as part of the install path for the CMake package files,
   #       e.g. /usr/local/lib/cmake/glog, where the <glog> suffix is hardcoded
   #       in glog's CMakeLists.  However, on Windows the project name *is*
   #       part of the install prefix: C:/Program Files/google-glog/[include,lib].
   #       However, by default CMake checks:
   #       C:/Program Files/<FIND_PACKAGE_ARGUMENT_NAME='glog'> which does not
   #       exist and thus detection fails.  Thus we use the NAMES to force the
   #       search to use both google-glog & glog.
   #
   # [1] http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:find_package
   find_package(glog QUIET
                     NAMES google-glog glog
                     HINTS ${glog_DIR} ${HOMEBREW_INSTALL_PREFIX}
                     NO_MODULE
                     NO_CMAKE_PACKAGE_REGISTRY
                     NO_CMAKE_BUILDS_PATH)
   if (glog_FOUND)
     glog_message(STATUS "Found installed version of glog: ${glog_DIR}")
   else()
     # Failed to find an installed version of glog, repeat search allowing
     # exported build directories.
     glog_message(STATUS "Failed to find installed glog CMake configuration, "
       "searching for glog build directories exported with CMake.")
     # Again pass NO_CMAKE_BUILDS_PATH, as we know that glog is exported and
     # do not want to treat projects built with the CMake GUI preferentially.
     find_package(glog QUIET
                       NAMES google-glog glog
                       NO_MODULE
                       NO_CMAKE_BUILDS_PATH)
     if (glog_FOUND)
       glog_message(STATUS "Found exported glog build directory: ${glog_DIR}")
     endif(glog_FOUND)
   endif(glog_FOUND)

   set(FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION ${glog_FOUND})

   if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
     glog_message(STATUS "Detected glog version: ${glog_VERSION}")
     set(GLOG_FOUND ${glog_FOUND})
     # glog wraps the include directories into the exported glog::glog target.
     set(GLOG_INCLUDE_DIR "")
     set(GLOG_LIBRARY glog::glog)
   else (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
     glog_message(STATUS "Failed to find an installed/exported CMake "
       "configuration for glog, will perform search for installed glog "
       "components.")
   endif (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
 endif(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)

 if (NOT GLOG_FOUND)
   # Either failed to find an exported glog CMake configuration, or user
   # told us not to use one.  Perform a manual search for all glog components.

   # Handle possible presence of lib prefix for libraries on MSVC, see
   # also GLOG_RESET_FIND_LIBRARY_PREFIX().
   if (MSVC)
     # Preserve the caller's original values for CMAKE_FIND_LIBRARY_PREFIXES
     # s/t we can set it back before returning.
     set(CALLERS_CMAKE_FIND_LIBRARY_PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
     # The empty string in this list is important, it represents the case when
     # the libraries have no prefix (shared libraries / DLLs).
     set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "" "${CMAKE_FIND_LIBRARY_PREFIXES}")
   endif (MSVC)

   # Search user-installed locations first, so that we prefer user installs
   # to system installs where both exist.
   list(APPEND GLOG_CHECK_INCLUDE_DIRS
     /usr/local/include
     /usr/local/homebrew/include # Mac OS X
     /opt/local/var/macports/software # Mac OS X.
     /opt/local/include
     /usr/include)
   # Windows (for C:/Program Files prefix).
   list(APPEND GLOG_CHECK_PATH_SUFFIXES
     glog/include
     glog/Include
     Glog/include
     Glog/Include
     google-glog/include # CMake installs with project name prefix.
     google-glog/Include)

   list(APPEND GLOG_CHECK_LIBRARY_DIRS
     /usr/local/lib
     /usr/local/homebrew/lib # Mac OS X.
     /opt/local/lib
     /usr/lib)
   # Windows (for C:/Program Files prefix).
   list(APPEND GLOG_CHECK_LIBRARY_SUFFIXES
     glog/lib
     glog/Lib
     Glog/lib
     Glog/Lib
     google-glog/lib # CMake installs with project name prefix.
     google-glog/Lib)

   # Search supplied hint directories first if supplied.
   find_path(GLOG_INCLUDE_DIR
     NAMES glog/logging.h
     HINTS ${GLOG_INCLUDE_DIR_HINTS}
     PATHS ${GLOG_CHECK_INCLUDE_DIRS}
     PATH_SUFFIXES ${GLOG_CHECK_PATH_SUFFIXES})
   if (NOT GLOG_INCLUDE_DIR OR
       NOT EXISTS ${GLOG_INCLUDE_DIR})
     glog_report_not_found(
       "Could not find glog include directory, set GLOG_INCLUDE_DIR "
       "to directory containing glog/logging.h")
   endif (NOT GLOG_INCLUDE_DIR OR
     NOT EXISTS ${GLOG_INCLUDE_DIR})

   find_library(GLOG_LIBRARY NAMES glog
     HINTS ${GLOG_LIBRARY_DIR_HINTS}
     PATHS ${GLOG_CHECK_LIBRARY_DIRS}
     PATH_SUFFIXES ${GLOG_CHECK_LIBRARY_SUFFIXES})
   if (NOT GLOG_LIBRARY OR
       NOT EXISTS ${GLOG_LIBRARY})
     glog_report_not_found(
       "Could not find glog library, set GLOG_LIBRARY "
       "to full path to libglog.")
   endif (NOT GLOG_LIBRARY OR
     NOT EXISTS ${GLOG_LIBRARY})

   # Mark internally as found, then verify. GLOG_REPORT_NOT_FOUND() unsets
   # if called.
   set(GLOG_FOUND TRUE)

   # Glog does not seem to provide any record of the version in its
   # source tree, thus cannot extract version.

   # Catch case when caller has set GLOG_INCLUDE_DIR in the cache / GUI and
   # thus FIND_[PATH/LIBRARY] are not called, but specified locations are
   # invalid, otherwise we would report the library as found.
   if (GLOG_INCLUDE_DIR AND
       NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
     glog_report_not_found(
       "Caller defined GLOG_INCLUDE_DIR:"
       " ${GLOG_INCLUDE_DIR} does not contain glog/logging.h header.")
   endif (GLOG_INCLUDE_DIR AND
     NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
   # TODO: This regex for glog library is pretty primitive, we use lowercase
   #       for comparison to handle Windows using CamelCase library names, could
   #       this check be better?
   string(TOLOWER "${GLOG_LIBRARY}" LOWERCASE_GLOG_LIBRARY)
   if (GLOG_LIBRARY AND
       NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".*glog[^/]*")
     glog_report_not_found(
       "Caller defined GLOG_LIBRARY: "
       "${GLOG_LIBRARY} does not match glog.")
   endif (GLOG_LIBRARY AND
     NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".*glog[^/]*")

   # add glog::glog target
   add_library(glog::glog INTERFACE IMPORTED)
   target_include_directories(glog::glog INTERFACE ${GLOG_INCLUDE_DIRS})
   target_link_libraries(glog::glog INTERFACE ${GLOG_LIBRARY})

   glog_reset_find_library_prefix()

 endif(NOT GLOG_FOUND)

 # Set standard CMake FindPackage variables if found.
 if (GLOG_FOUND)
   set(GLOG_INCLUDE_DIRS ${GLOG_INCLUDE_DIR})
   set(GLOG_LIBRARIES ${GLOG_LIBRARY})
 endif (GLOG_FOUND)

 # If we are using an exported CMake glog target, the include directories are
 # wrapped into the target itself, and do not have to be (and are not)
 # separately specified.  In which case, we should not add GLOG_INCLUDE_DIRS
 # to the list of required variables in order that glog be reported as found.
 if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
   set(GLOG_REQUIRED_VARIABLES GLOG_LIBRARIES)
 else()
   set(GLOG_REQUIRED_VARIABLES GLOG_INCLUDE_DIRS GLOG_LIBRARIES)
 endif()

 # Handle REQUIRED / QUIET optional arguments.
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Glog DEFAULT_MSG
   ${GLOG_REQUIRED_VARIABLES})

 # Only mark internal variables as advanced if we found glog, otherwise
 # leave them visible in the standard GUI for the user to set manually.
 if (GLOG_FOUND)
   mark_as_advanced(FORCE GLOG_INCLUDE_DIR
                          GLOG_LIBRARY
                          glog_DIR) # Autogenerated by find_package(glog)
 endif (GLOG_FOUND)
	# Ceres Solver - A fast non-linear least squares minimizer
	# Copyright 2023 Google Inc. All rights reserved.
	# http://ceres-solver.org/
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions are met:
	#
	# * Redistributions of source code must retain the above copyright notice,
	# this list of conditions and the following disclaimer.
	# * Redistributions in binary form must reproduce the above copyright notice,
	# this list of conditions and the following disclaimer in the documentation
	# and/or other materials provided with the distribution.
	# * Neither the name of Google Inc. nor the names of its contributors may be
	# used to endorse or promote products derived from this software without
	# specific prior written permission.
	#
	# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	# POSSIBILITY OF SUCH DAMAGE.
	#
	# Author: alexs.mac@gmail.com (Alex Stewart)
	#

	# FindGlog.cmake - Find Google glog logging library.
	#
	# This module defines the following variables:
	#
	# GLOG_FOUND: TRUE iff glog is found.
	# GLOG_INCLUDE_DIRS: Include directories for glog.
	# GLOG_LIBRARIES: Libraries required to link glog.
	# FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION: True iff the version of glog found
	# was built & installed / exported
	# as a CMake package.
	#
	# The following variables control the behaviour of this module:
	#
	# GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION: TRUE/FALSE, iff TRUE then
	# then prefer using an exported CMake configuration
	# generated by glog > 0.3.4 over searching for the
	# glog components manually. Otherwise (FALSE)
	# ignore any exported glog CMake configurations and
	# always perform a manual search for the components.
	# Default: TRUE iff user does not define this variable
	# before we are called, and does NOT specify either
	# GLOG_INCLUDE_DIR_HINTS or GLOG_LIBRARY_DIR_HINTS
	# otherwise FALSE.
	# GLOG_INCLUDE_DIR_HINTS: List of additional directories in which to
	# search for glog includes, e.g: /timbuktu/include.
	# GLOG_LIBRARY_DIR_HINTS: List of additional directories in which to
	# search for glog libraries, e.g: /timbuktu/lib.
	#
	# The following variables are also defined by this module, but in line with
	# CMake recommended FindPackage() module style should NOT be referenced directly
	# by callers (use the plural variables detailed above instead). These variables
	# do however affect the behaviour of the module via FIND_[PATH/LIBRARY]() which
	# are NOT re-called (i.e. search for library is not repeated) if these variables
	# are set with valid values _in the CMake cache_. This means that if these
	# variables are set directly in the cache, either by the user in the CMake GUI,
	# or by the user passing -DVAR=VALUE directives to CMake when called (which
	# explicitly defines a cache variable), then they will be used verbatim,
	# bypassing the HINTS variables and other hard-coded search locations.
	#
	# GLOG_INCLUDE_DIR: Include directory for glog, not including the
	# include directory of any dependencies.
	# GLOG_LIBRARY: glog library, not including the libraries of any
	# dependencies.

	# Reset CALLERS_CMAKE_FIND_LIBRARY_PREFIXES to its value when
	# FindGlog was invoked.
	macro(GLOG_RESET_FIND_LIBRARY_PREFIX)
	if (MSVC AND CALLERS_CMAKE_FIND_LIBRARY_PREFIXES)
	set(CMAKE_FIND_LIBRARY_PREFIXES "${CALLERS_CMAKE_FIND_LIBRARY_PREFIXES}")
	endif()
	endmacro(GLOG_RESET_FIND_LIBRARY_PREFIX)

	# Called if we failed to find glog or any of it's required dependencies,
	# unsets all public (designed to be used externally) variables and reports
	# error message at priority depending upon [REQUIRED/QUIET/<NONE>] argument.
	macro(GLOG_REPORT_NOT_FOUND REASON_MSG)
	unset(GLOG_FOUND)
	unset(GLOG_INCLUDE_DIRS)
	unset(GLOG_LIBRARIES)
	# Make results of search visible in the CMake GUI if glog has not
	# been found so that user does not have to toggle to advanced view.
	mark_as_advanced(CLEAR GLOG_INCLUDE_DIR
	GLOG_LIBRARY)

	glog_reset_find_library_prefix()

	# Note <package>_FIND_[REQUIRED/QUIETLY] variables defined by FindPackage()
	# use the camelcase library name, not uppercase.
	if (Glog_FIND_QUIETLY)
	message(STATUS "Failed to find glog - " ${REASON_MSG} ${ARGN})
	elseif (Glog_FIND_REQUIRED)
	message(FATAL_ERROR "Failed to find glog - " ${REASON_MSG} ${ARGN})
	else()
	# Neither QUIETLY nor REQUIRED, use no priority which emits a message
	# but continues configuration and allows generation.
	message("-- Failed to find glog - " ${REASON_MSG} ${ARGN})
	endif ()
	return()
	endmacro(GLOG_REPORT_NOT_FOUND)

	# glog_message([mode] "message text")
	#
	# Wraps the standard cmake 'message' command, but suppresses output
	# if the QUIET flag was passed to the find_package(Glog ...) call.
	function(GLOG_MESSAGE)
	if (NOT Glog_FIND_QUIETLY)
	message(${ARGN})
	endif()
	endfunction()

	# Protect against any alternative find_package scripts for this library having
	# been called previously (in a client project) which set GLOG_FOUND, but not
	# the other variables we require / set here which could cause the search logic
	# here to fail.
	unset(GLOG_FOUND)

	# -----------------------------------------------------------------
	# By default, if the user has expressed no preference for using an exported
	# glog CMake configuration over performing a search for the installed
	# components, and has not specified any hints for the search locations, then
	# prefer a glog exported configuration if available.
	if (NOT DEFINED GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION
	AND NOT GLOG_INCLUDE_DIR_HINTS
	AND NOT GLOG_LIBRARY_DIR_HINTS)
	glog_message(STATUS "No preference for use of exported glog CMake "
	"configuration set, and no hints for include/library directories provided. "
	"Defaulting to preferring an installed/exported glog CMake configuration "
	"if available.")
	set(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION TRUE)
	endif()

	# On macOS, add the Homebrew prefix (with appropriate suffixes) to the
	# respective HINTS directories (after any user-specified locations). This
	# handles Homebrew installations into non-standard locations (not /usr/local).
	# We do not use CMAKE_PREFIX_PATH for this as given the search ordering of
	# find_xxx(), doing so would override any user-specified HINTS locations with
	# the Homebrew version if it exists.
	if (CMAKE_SYSTEM_NAME MATCHES "Darwin")
	find_program(HOMEBREW_EXECUTABLE brew)
	mark_as_advanced(FORCE HOMEBREW_EXECUTABLE)
	if (HOMEBREW_EXECUTABLE)
	# Detected a Homebrew install, query for its install prefix.
	execute_process(COMMAND ${HOMEBREW_EXECUTABLE} --prefix
	OUTPUT_VARIABLE HOMEBREW_INSTALL_PREFIX
	OUTPUT_STRIP_TRAILING_WHITESPACE)
	glog_message(STATUS "Detected Homebrew with install prefix: "
	"${HOMEBREW_INSTALL_PREFIX}, adding to CMake search paths.")
	list(APPEND GLOG_INCLUDE_DIR_HINTS "${HOMEBREW_INSTALL_PREFIX}/include")
	list(APPEND GLOG_LIBRARY_DIR_HINTS "${HOMEBREW_INSTALL_PREFIX}/lib")
	endif()
	endif()

	if (GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)
	# Try to find an exported CMake configuration for glog, as generated by
	# glog versions > 0.3.4
	#
	# We search twice, s/t we can invert the ordering of precedence used by
	# find_package() for exported package build directories, and installed
	# packages (found via CMAKE_SYSTEM_PREFIX_PATH), listed as items 6) and 7)
	# respectively in [1].
	#
	# By default, exported build directories are (in theory) detected first, and
	# this is usually the case on Windows. However, on OS X & Linux, the install
	# path (/usr/local) is typically present in the PATH environment variable
	# which is checked in item 4) in [1] (i.e. before both of the above, unless
	# NO_SYSTEM_ENVIRONMENT_PATH is passed). As such on those OSs installed
	# packages are usually detected in preference to exported package build
	# directories.
	#
	# To ensure a more consistent response across all OSs, and as users usually
	# want to prefer an installed version of a package over a locally built one
	# where both exist (esp. as the exported build directory might be removed
	# after installation), we first search with NO_CMAKE_PACKAGE_REGISTRY which
	# means any build directories exported by the user are ignored, and thus
	# installed directories are preferred. If this fails to find the package
	# we then research again, but without NO_CMAKE_PACKAGE_REGISTRY, so any
	# exported build directories will now be detected.
	#
	# To prevent confusion on Windows, we also pass NO_CMAKE_BUILDS_PATH (which
	# is item 5) in [1]), to not preferentially use projects that were built
	# recently with the CMake GUI to ensure that we always prefer an installed
	# version if available.
	#
	# NOTE: We use the NAMES option as glog erroneously uses 'google-glog' as its
	# project name when built with CMake, but exports itself as just 'glog'.
	# On Linux/OS X this does not break detection as the project name is
	# not used as part of the install path for the CMake package files,
	# e.g. /usr/local/lib/cmake/glog, where the <glog> suffix is hardcoded
	# in glog's CMakeLists. However, on Windows the project name is
	# part of the install prefix: C:/Program Files/google-glog/[include,lib].
	# However, by default CMake checks:
	# C:/Program Files/<FIND_PACKAGE_ARGUMENT_NAME='glog'> which does not
	# exist and thus detection fails. Thus we use the NAMES to force the
	# search to use both google-glog & glog.
	#
	# [1] http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:find_package
	find_package(glog QUIET
	NAMES google-glog glog
	HINTS ${glog_DIR} ${HOMEBREW_INSTALL_PREFIX}
	NO_MODULE
	NO_CMAKE_PACKAGE_REGISTRY
	NO_CMAKE_BUILDS_PATH)
	if (glog_FOUND)
	glog_message(STATUS "Found installed version of glog: ${glog_DIR}")
	else()
	# Failed to find an installed version of glog, repeat search allowing
	# exported build directories.
	glog_message(STATUS "Failed to find installed glog CMake configuration, "
	"searching for glog build directories exported with CMake.")
	# Again pass NO_CMAKE_BUILDS_PATH, as we know that glog is exported and
	# do not want to treat projects built with the CMake GUI preferentially.
	find_package(glog QUIET
	NAMES google-glog glog
	NO_MODULE
	NO_CMAKE_BUILDS_PATH)
	if (glog_FOUND)
	glog_message(STATUS "Found exported glog build directory: ${glog_DIR}")
	endif(glog_FOUND)
	endif(glog_FOUND)

	set(FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION ${glog_FOUND})

	if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
	glog_message(STATUS "Detected glog version: ${glog_VERSION}")
	set(GLOG_FOUND ${glog_FOUND})
	# glog wraps the include directories into the exported glog::glog target.
	set(GLOG_INCLUDE_DIR "")
	set(GLOG_LIBRARY glog::glog)
	else (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
	glog_message(STATUS "Failed to find an installed/exported CMake "
	"configuration for glog, will perform search for installed glog "
	"components.")
	endif (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
	endif(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)

	if (NOT GLOG_FOUND)
	# Either failed to find an exported glog CMake configuration, or user
	# told us not to use one. Perform a manual search for all glog components.

	# Handle possible presence of lib prefix for libraries on MSVC, see
	# also GLOG_RESET_FIND_LIBRARY_PREFIX().
	if (MSVC)
	# Preserve the caller's original values for CMAKE_FIND_LIBRARY_PREFIXES
	# s/t we can set it back before returning.
	set(CALLERS_CMAKE_FIND_LIBRARY_PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
	# The empty string in this list is important, it represents the case when
	# the libraries have no prefix (shared libraries / DLLs).
	set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "" "${CMAKE_FIND_LIBRARY_PREFIXES}")
	endif (MSVC)

	# Search user-installed locations first, so that we prefer user installs
	# to system installs where both exist.
	list(APPEND GLOG_CHECK_INCLUDE_DIRS
	/usr/local/include
	/usr/local/homebrew/include # Mac OS X
	/opt/local/var/macports/software # Mac OS X.
	/opt/local/include
	/usr/include)
	# Windows (for C:/Program Files prefix).
	list(APPEND GLOG_CHECK_PATH_SUFFIXES
	glog/include
	glog/Include
	Glog/include
	Glog/Include
	google-glog/include # CMake installs with project name prefix.
	google-glog/Include)

	list(APPEND GLOG_CHECK_LIBRARY_DIRS
	/usr/local/lib
	/usr/local/homebrew/lib # Mac OS X.
	/opt/local/lib
	/usr/lib)
	# Windows (for C:/Program Files prefix).
	list(APPEND GLOG_CHECK_LIBRARY_SUFFIXES
	glog/lib
	glog/Lib
	Glog/lib
	Glog/Lib
	google-glog/lib # CMake installs with project name prefix.
	google-glog/Lib)

	# Search supplied hint directories first if supplied.
	find_path(GLOG_INCLUDE_DIR
	NAMES glog/logging.h
	HINTS ${GLOG_INCLUDE_DIR_HINTS}
	PATHS ${GLOG_CHECK_INCLUDE_DIRS}
	PATH_SUFFIXES ${GLOG_CHECK_PATH_SUFFIXES})
	if (NOT GLOG_INCLUDE_DIR OR
	NOT EXISTS ${GLOG_INCLUDE_DIR})
	glog_report_not_found(
	"Could not find glog include directory, set GLOG_INCLUDE_DIR "
	"to directory containing glog/logging.h")
	endif (NOT GLOG_INCLUDE_DIR OR
	NOT EXISTS ${GLOG_INCLUDE_DIR})

	find_library(GLOG_LIBRARY NAMES glog
	HINTS ${GLOG_LIBRARY_DIR_HINTS}
	PATHS ${GLOG_CHECK_LIBRARY_DIRS}
	PATH_SUFFIXES ${GLOG_CHECK_LIBRARY_SUFFIXES})
	if (NOT GLOG_LIBRARY OR
	NOT EXISTS ${GLOG_LIBRARY})
	glog_report_not_found(
	"Could not find glog library, set GLOG_LIBRARY "
	"to full path to libglog.")
	endif (NOT GLOG_LIBRARY OR
	NOT EXISTS ${GLOG_LIBRARY})

	# Mark internally as found, then verify. GLOG_REPORT_NOT_FOUND() unsets
	# if called.
	set(GLOG_FOUND TRUE)

	# Glog does not seem to provide any record of the version in its
	# source tree, thus cannot extract version.

	# Catch case when caller has set GLOG_INCLUDE_DIR in the cache / GUI and
	# thus FIND_[PATH/LIBRARY] are not called, but specified locations are
	# invalid, otherwise we would report the library as found.
	if (GLOG_INCLUDE_DIR AND
	NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
	glog_report_not_found(
	"Caller defined GLOG_INCLUDE_DIR:"
	" ${GLOG_INCLUDE_DIR} does not contain glog/logging.h header.")
	endif (GLOG_INCLUDE_DIR AND
	NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
	# TODO: This regex for glog library is pretty primitive, we use lowercase
	# for comparison to handle Windows using CamelCase library names, could
	# this check be better?
	string(TOLOWER "${GLOG_LIBRARY}" LOWERCASE_GLOG_LIBRARY)
	if (GLOG_LIBRARY AND
	NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".glog[^/]")
	glog_report_not_found(
	"Caller defined GLOG_LIBRARY: "
	"${GLOG_LIBRARY} does not match glog.")
	endif (GLOG_LIBRARY AND
	NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".glog[^/]")

	# add glog::glog target
	add_library(glog::glog INTERFACE IMPORTED)
	target_include_directories(glog::glog INTERFACE ${GLOG_INCLUDE_DIRS})
	target_link_libraries(glog::glog INTERFACE ${GLOG_LIBRARY})

	glog_reset_find_library_prefix()

	endif(NOT GLOG_FOUND)

	# Set standard CMake FindPackage variables if found.
	if (GLOG_FOUND)
	set(GLOG_INCLUDE_DIRS ${GLOG_INCLUDE_DIR})
	set(GLOG_LIBRARIES ${GLOG_LIBRARY})
	endif (GLOG_FOUND)

	# If we are using an exported CMake glog target, the include directories are
	# wrapped into the target itself, and do not have to be (and are not)
	# separately specified. In which case, we should not add GLOG_INCLUDE_DIRS
	# to the list of required variables in order that glog be reported as found.
	if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
	set(GLOG_REQUIRED_VARIABLES GLOG_LIBRARIES)
	else()
	set(GLOG_REQUIRED_VARIABLES GLOG_INCLUDE_DIRS GLOG_LIBRARIES)
	endif()

	# Handle REQUIRED / QUIET optional arguments.
	include(FindPackageHandleStandardArgs)
	find_package_handle_standard_args(Glog DEFAULT_MSG
	${GLOG_REQUIRED_VARIABLES})

	# Only mark internal variables as advanced if we found glog, otherwise
	# leave them visible in the standard GUI for the user to set manually.
	if (GLOG_FOUND)
	mark_as_advanced(FORCE GLOG_INCLUDE_DIR
	GLOG_LIBRARY
	glog_DIR) # Autogenerated by find_package(glog)
	endif (GLOG_FOUND)