add 2nd, more powerful mode to find_package_handle_standard_args()

This additional mode also supports version checking and should be
easily extendible, e.g. for COMPONENT stuff.
Updated FindBISON.cmake as first user of this new mode.
Docs updated.

Alex

Modules/FindBISON.cmake

@@ -5,6 +5,9 @@
 #  BISON_VERSION - version of bison
 #  BISON_FOUND - true if the program was found
 #
+# The minimum required version of bison can be specified using the
+# standard CMake syntax, e.g. find_package(BISON 2.1.3)
+#
 # If bison is found, the module defines the macros:
 #  BISON_TARGET(<Name> <YaccInput> <CodeOutput> [VERBOSE <file>]
 #              [COMPILE_FLAGS <string>])
@@ -149,6 +152,7 @@ IF(BISON_EXECUTABLE)
 ENDIF(BISON_EXECUTABLE)
 
 INCLUDE(FindPackageHandleStandardArgs)
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(BISON DEFAULT_MSG BISON_EXECUTABLE)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(BISON REQUIRED_VARS  BISON_EXECUTABLE
+                                        VERSION_VAR BISON_VERSION)
 
 # FindBISON.cmake ends here

Modules/FindPackageHandleStandardArgs.cmake

@@ -1,21 +1,56 @@
-# FIND_PACKAGE_HANDLE_STANDARD_ARGS(NAME (DEFAULT_MSG|"Custom failure message") VAR1 ... )
+# FIND_PACKAGE_HANDLE_STANDARD_ARGS(<name> ... )
-#    This macro is intended to be used in FindXXX.cmake modules files.
+#    This function is intended to be used in FindXXX.cmake modules files.
-#    It handles the REQUIRED and QUIET argument to FIND_PACKAGE() and
+#    It handles the REQUIRED, QUIET and version-related arguments to FIND_PACKAGE().
-#    it also sets the <UPPERCASED_NAME>_FOUND variable.
+#    It also sets the <UPPERCASED_NAME>_FOUND variable.
-#    The package is found if all variables listed are TRUE.
+#    The package is considered found if all variables <var1>... listed contain
-#    Example:
+#    valid results, e.g. valid filepaths.
 #
-#    FIND_PACKAGE_HANDLE_STANDARD_ARGS(LibXml2 DEFAULT_MSG LIBXML2_LIBRARIES LIBXML2_INCLUDE_DIR)
+#    There are two modes of this function. The first argument in both modes is
+#    the name of the Find-module where it is called (in original casing).
 #
-#    LibXml2 is considered to be found, if both LIBXML2_LIBRARIES and 
+#    The first simple mode looks like this:
+#    FIND_PACKAGE_HANDLE_STANDARD_ARGS(<name> (DEFAULT_MSG|"Custom failure message") <var1>...<varN> )
+#    If the variables <var1> to <varN> are all valid, then <UPPERCASED_NAME>_FOUND
+#    will be set to TRUE.
+#    If DEFAULT_MSG is given as second argument, then the function will generate
+#    itself useful success and error messages. You can also supply a custom error message
+#    for the failure case. This is not recommended.
+#
+#    The second mode is more powerful and also supports version checking:
+#    FIND_PACKAGE_HANDLE_STANDARD_ARGS(NAME [REQUIRED_VARS <var1>...<varN>]
+#                                           [VERSION_VAR   <versionvar>
+#                                           [FAIL_MESSAGE "Custom failure message"] )
+#
+#    As above, if <var1> through <varN> are all valid, <UPPERCASED_NAME>_FOUND
+#    will be set to TRUE.
+#    Via FAIL_MESSAGE a custom failure message can be specified, if this is not
+#    used, the default message will be displayed.
+#    Following VERSION_VAR the name of the variable can be specified which holds
+#    the version of the package which has been found. If this is done, this version
+#    will be checked against the (potentially) specified required version used
+#    in the find_package() call. The EXACT keyword is also handled. The default
+#    messages include information about the required version and the version
+#    which has been actually found, both if the version is ok or not.
+#    Example for mode 1:
+#
+#    FIND_PACKAGE_HANDLE_STANDARD_ARGS(LibXml2  DEFAULT_MSG  LIBXML2_LIBRARY LIBXML2_INCLUDE_DIR)
+#
+#    LibXml2 is considered to be found, if both LIBXML2_LIBRARY and
 #    LIBXML2_INCLUDE_DIR are valid. Then also LIBXML2_FOUND is set to TRUE.
 #    If it is not found and REQUIRED was used, it fails with FATAL_ERROR,
 #    independent whether QUIET was used or not.
-#    If it is found, the location is reported using the VAR1 argument, so 
+#    If it is found, success will be reported, including the content of <var1>.
-#    here a message "Found LibXml2: /usr/lib/libxml2.so" will be printed out.
+#    On repeated Cmake runs, the same message won't be printed again.
-#    If the second argument is DEFAULT_MSG, the message in the failure case will 
+#
-#    be "Could NOT find LibXml2", if you don't like this message you can specify
+#    Example for mode 2:
-#    your own custom failure message there.
+#
+#    FIND_PACKAGE_HANDLE_STANDARD_ARGS(BISON  REQUIRED_VARS BISON_EXECUTABLE
+#                                             VERSION_VAR BISON_VERSION)
+#    In this case, BISON is considered to be found if the variable(s) listed
+#    after REQUIRED_VAR are all valid, i.e. BISON_EXECUTABLE in this case.
+#    Also the version of BISON will be checked by using the version contained
+#    in BISON_VERSION.
+#    Since no FAIL_MESSAGE is given, the default messages will be printed.
 
 #=============================================================================
 # Copyright 2007-2009 Kitware, Inc.
@@ -31,13 +66,89 @@
 #  License text for the above reference.)
 
 INCLUDE(FindPackageMessage)
-FUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS _NAME _FAIL_MSG _VAR1 )
 
-  IF("${_FAIL_MSG}" STREQUAL "DEFAULT_MSG")
+# Checks a list of strings (typically function/macro parameters) whether it contains a keyword
+# (_keyword) and return the value(s) following this keyword in _outputVar.
+# If _multipleValues is true, this can be more than one value.
+# Then end of the values for a keyword is then determined by checking whether the
+# next argument is contained in _allKeywordsList.
+FUNCTION(FPHSA_GET_OPTION_VALUE _keyword _outputVar _allArgsList _allKeywordsList _multipleValues)
+  UNSET(${_outputVar})
+  UNSET(_removeIndices)
+
+  SET(_insideValues FALSE)
+  SET(_counter 0)
+  FOREACH(_currentArg ${${_allArgsList}})
+    IF(NOT _insideValues)  # first check that we find the keyword we are currently interested in...
+      IF("${_currentArg}" STREQUAL "${_keyword}")
+        SET(_insideValues TRUE)
+        LIST(APPEND _removeIndices ${_counter})
+      ENDIF("${_currentArg}" STREQUAL "${_keyword}")
+    ELSE(NOT _insideValues)
+
+      LIST(FIND ${_allKeywordsList} "${_currentArg}" _index)  # ... then this marks the end of the arguments belonging to this keyword
+      IF(${_index} EQUAL -1)
+        LIST(APPEND _result ${_currentArg})
+        LIST(APPEND _removeIndices ${_counter}) # collect the indices of the strings we found to remove them from the list afterwards
+        IF(NOT _multipleValues)
+          BREAK()
+        ENDIF(NOT _multipleValues)
+      ELSE(${_index} EQUAL -1)
+        SET(_insideValues FALSE)
+        BREAK()
+      ENDIF(${_index} EQUAL -1)
+    ENDIF(NOT _insideValues)
+
+    MATH(EXPR _counter "${_counter} + 1")
+
+  ENDFOREACH(_currentArg ${${_allArgsList}})
+
+  IF(DEFINED _removeIndices)
+    LIST(REMOVE_AT ${_allArgsList} ${_removeIndices})
+  ENDIF(DEFINED _removeIndices)
+
+  SET(${_outputVar} ${_result} PARENT_SCOPE)
+  SET(${_allArgsList} ${${_allArgsList}} PARENT_SCOPE)
+
+ENDFUNCTION(FPHSA_GET_OPTION_VALUE _keyword _outputVar _allArgsList _allKeywordsList _multipleValues)
+
+
+FUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS _NAME _FIRST_ARG _VAR1)
+
+  SET(_KEYWORDS_FOR_EXTENDED_MODE  FAIL_MESSAGE REQUIRED_VARS VERSION_VAR )
+  LIST(FIND _KEYWORDS_FOR_EXTENDED_MODE "${_FIRST_ARG}" INDEX)
+
+  IF(${INDEX} EQUAL -1)
+    SET(_FAIL_MESSAGE ${_FIRST_ARG})
+    SET(_REQUIRED_VARS ${_VAR1} ${ARGN})
+    SET(_VERSION_VAR)
+  ELSE(${INDEX} EQUAL -1)
+    SET(ALL_ARGS ${_FIRST_ARG} ${_VAR1} ${ARGN})
+
+    FPHSA_GET_OPTION_VALUE("FAIL_MESSAGE"    _FAIL_MESSAGE    ALL_ARGS _KEYWORDS_FOR_EXTENDED_MODE FALSE)
+    FPHSA_GET_OPTION_VALUE("REQUIRED_VARS"   _REQUIRED_VARS   ALL_ARGS _KEYWORDS_FOR_EXTENDED_MODE TRUE)
+    FPHSA_GET_OPTION_VALUE("VERSION_VAR"     _VERSION_VAR     ALL_ARGS _KEYWORDS_FOR_EXTENDED_MODE FALSE)
+
+    IF(ALL_ARGS)
+      MESSAGE(FATAL_ERROR "Unknown keywords given to FIND_PACKAGE_HANDLE_STANDARD_ARGS(): \"${ALL_ARGS}\"")
+    ENDIF(ALL_ARGS)
+
+    IF(NOT _FAIL_MESSAGE)
+      SET(_FAIL_MESSAGE  "DEFAULT_MSG")
+    ENDIF(NOT _FAIL_MESSAGE)
+  ENDIF(${INDEX} EQUAL -1)
+
+# now that we collected all arguments, process them
+
+  IF("${_FAIL_MESSAGE}" STREQUAL "DEFAULT_MSG")
     SET(_FAIL_MESSAGE "Could NOT find ${_NAME}")
-  ELSE("${_FAIL_MSG}" STREQUAL "DEFAULT_MSG")
+  ENDIF("${_FAIL_MESSAGE}" STREQUAL "DEFAULT_MSG")
-    SET(_FAIL_MESSAGE "${_FAIL_MSG}")
+
-  ENDIF("${_FAIL_MSG}" STREQUAL "DEFAULT_MSG")
+  IF(NOT _REQUIRED_VARS)
+    MESSAGE(FATAL_ERROR "No REQUIRED_VARS specified for FIND_PACKAGE_HANDLE_STANDARD_ARGS()")
+  ENDIF(NOT _REQUIRED_VARS)
+
+  LIST(GET _REQUIRED_VARS 0 _FIRST_REQUIRED_VAR)
 
   STRING(TOUPPER ${_NAME} _NAME_UPPER)
 
@@ -46,15 +157,8 @@ FUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS _NAME _FAIL_MSG _VAR1 )
   SET(MISSING_VARS "")
   SET(DETAILS "")
   SET(${_NAME_UPPER}_FOUND TRUE)
-  IF(NOT ${_VAR1})
-    SET(${_NAME_UPPER}_FOUND FALSE)
-    SET(MISSING_VARS " ${_VAR1}")
-  ELSE(NOT ${_VAR1})
-    SET(DETAILS "${DETAILS}[${${_VAR1}}]")
-  ENDIF(NOT ${_VAR1})
-
   # check if all passed variables are valid
-  FOREACH(_CURRENT_VAR ${ARGN})
+  FOREACH(_CURRENT_VAR ${_REQUIRED_VARS})
     IF(NOT ${_CURRENT_VAR})
       SET(${_NAME_UPPER}_FOUND FALSE)
       SET(MISSING_VARS "${MISSING_VARS} ${_CURRENT_VAR}")
@@ -63,18 +167,84 @@ FUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS _NAME _FAIL_MSG _VAR1 )
     ENDIF(NOT ${_CURRENT_VAR})
   ENDFOREACH(_CURRENT_VAR)
 
+
+  # version handling:
+  SET(VERSION_MSG "")
+  SET(VERSION_OK TRUE)
+  IF (${_NAME}_FIND_VERSION)
+
+    # if the package was found, check for the version using <NAME>_FIND_VERSION
     IF (${_NAME_UPPER}_FOUND)
-    FIND_PACKAGE_MESSAGE(${_NAME} "Found ${_NAME}: ${${_VAR1}}" "${DETAILS}")
+      SET(VERSION ${${_VERSION_VAR}} )
+
+      IF(VERSION)
+
+        IF(${_NAME}_FIND_VERSION_EXACT)       # exact version required
+          IF (NOT "${${_NAME}_FIND_VERSION}" VERSION_EQUAL "${VERSION}")
+            SET(VERSION_MSG " Found version \"${VERSION}\", but required is exact version \"${${_NAME}_FIND_VERSION}\"")
+            SET(VERSION_OK FALSE)
+          ELSE (NOT "${${_NAME}_FIND_VERSION}" VERSION_EQUAL "${VERSION}")
+            SET(VERSION_MSG " (found exact version \"${VERSION}\")")
+          ENDIF (NOT "${${_NAME}_FIND_VERSION}" VERSION_EQUAL "${VERSION}")
+
+        ELSE(${_NAME}_FIND_VERSION_EXACT)     # minimum version specified:
+          IF ("${${_NAME}_FIND_VERSION}" VERSION_GREATER "${VERSION}")
+            SET(VERSION_MSG " Found version \"${VERSION}\", but required is at least \"${${_NAME}_FIND_VERSION}\"")
+            SET(VERSION_OK FALSE)
+          ELSE ("${${_NAME}_FIND_VERSION}" VERSION_GREATER "${VERSION}")
+            SET(VERSION_MSG " (found version \"${VERSION}\", required is \"${${_NAME}_FIND_VERSION}\")")
+          ENDIF ("${${_NAME}_FIND_VERSION}" VERSION_GREATER "${VERSION}")
+        ENDIF(${_NAME}_FIND_VERSION_EXACT)
+
+# Uncomment the following two lines to see to which Find-modules the VERSION_VAR keywords still need to be added:
+#      ELSE(VERSION)
+#        SET(VERSION_MSG " (WARNING: Required version is \"${${_NAME}_FIND_VERSION}\", but version of ${_NAME} is unknown)")
+      ENDIF(VERSION)
+
+    # if the package was not found, but a version was given, add that to the output:
     ELSE (${_NAME_UPPER}_FOUND)
+      IF(${_NAME}_FIND_VERSION_EXACT)
+         SET(VERSION_MSG " (Required is exact version \"${${_NAME}_FIND_VERSION}\")")
+      ELSE(${_NAME}_FIND_VERSION_EXACT)
+         SET(VERSION_MSG " (Required is at least version \"${${_NAME}_FIND_VERSION}\")")
+      ENDIF(${_NAME}_FIND_VERSION_EXACT)
+    ENDIF (${_NAME_UPPER}_FOUND)
+  ENDIF (${_NAME}_FIND_VERSION)
+
+  IF(VERSION_OK)
+    SET(DETAILS "${DETAILS}[v${${VERSION}}]")
+  ELSE(VERSION_OK)
+    SET(${_NAME_UPPER}_FOUND FALSE)
+  ENDIF(VERSION_OK)
+
+
+  # print the result:
+  IF (${_NAME_UPPER}_FOUND)
+    FIND_PACKAGE_MESSAGE(${_NAME} "Found ${_NAME}: ${${_FIRST_REQUIRED_VAR}} ${VERSION_MSG}" "${DETAILS}")
+  ELSE (${_NAME_UPPER}_FOUND)
+    IF(NOT VERSION_OK)
+
       IF (${_NAME}_FIND_REQUIRED)
-        MESSAGE(FATAL_ERROR "${_FAIL_MESSAGE} (missing: ${MISSING_VARS})")
+          MESSAGE(FATAL_ERROR "${_FAIL_MESSAGE}: ${VERSION_MSG} (found ${${_FIRST_REQUIRED_VAR}})")
       ELSE (${_NAME}_FIND_REQUIRED)
         IF (NOT ${_NAME}_FIND_QUIETLY)
-        MESSAGE(STATUS "${_FAIL_MESSAGE}  (missing: ${MISSING_VARS})")
+          MESSAGE(STATUS "${_FAIL_MESSAGE}: ${VERSION_MSG} (found ${${_FIRST_REQUIRED_VAR}})")
         ENDIF (NOT ${_NAME}_FIND_QUIETLY)
       ENDIF (${_NAME}_FIND_REQUIRED)
+
+    ELSE(NOT VERSION_OK)
+
+      IF (${_NAME}_FIND_REQUIRED)
+          MESSAGE(FATAL_ERROR "${_FAIL_MESSAGE} (missing: ${MISSING_VARS}) ${VERSION_MSG}")
+      ELSE (${_NAME}_FIND_REQUIRED)
+        IF (NOT ${_NAME}_FIND_QUIETLY)
+          MESSAGE(STATUS "${_FAIL_MESSAGE}  (missing: ${MISSING_VARS}) ${VERSION_MSG}")
+        ENDIF (NOT ${_NAME}_FIND_QUIETLY)
+      ENDIF (${_NAME}_FIND_REQUIRED)
+    ENDIF(NOT VERSION_OK)
+
   ENDIF (${_NAME_UPPER}_FOUND)
 
   SET(${_NAME_UPPER}_FOUND ${${_NAME_UPPER}_FOUND} PARENT_SCOPE)
 
-ENDFUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS)
+ENDFUNCTION(FIND_PACKAGE_HANDLE_STANDARD_ARGS _FIRST_ARG)