FindProtobuf: Better MSVC support, Searching for protobuf lite

Add support for finding debug libraries
Add support for searching Google provided MSVC project dir structure for libs
Add support for finding Protobuf "Lite" libraries

Modules/FindProtobuf.cmake

@@ -1,15 +1,31 @@
 # Locate and configure the Google Protocol Buffers library.
+#
+# The following variables can be set and are optional:
+#
+#   PROTOBUF_SRC_ROOT_FOLDER - When compiling with MSVC, if this cache variable is set
+#                              the protobuf-default VS project build locations
+#                              (vsprojects/Debug & vsprojects/Release) will be searched
+#                              for libraries and binaries.
+#
 # Defines the following variables:
 #
-#   PROTOBUF_FOUND - Found the Google Protocol Buffers library
+#   PROTOBUF_FOUND - Found the Google Protocol Buffers library (libprotobuf & header files)
 #   PROTOBUF_INCLUDE_DIRS - Include directories for Google Protocol Buffers
-#   PROTOBUF_LIBRARIES - The protobuf library
+#   PROTOBUF_LIBRARIES - The protobuf libraries
+# [New in CMake 2.8.5]
+#   PROTOBUF_PROTOC_LIBRARIES - The protoc libraries
+#   PROTOBUF_LITE_LIBRARIES - The protobuf-lite libraries
 #
-# The following cache variables are also defined:
+# The following cache variables are also available to set or use:
 #   PROTOBUF_LIBRARY - The protobuf library
 #   PROTOBUF_PROTOC_LIBRARY   - The protoc library
 #   PROTOBUF_INCLUDE_DIR - The include directory for protocol buffers
 #   PROTOBUF_PROTOC_EXECUTABLE - The protoc compiler
+# [New in CMake 2.8.5]
+#   PROTOBUF_LIBRARY_DEBUG - The protobuf library (debug)
+#   PROTOBUF_PROTOC_LIBRARY_DEBUG   - The protoc library (debug)
+#   PROTOBUF_LITE_LIBRARY - The protobuf lite library
+#   PROTOBUF_LITE_LIBRARY_DEBUG - The protobuf lite library (debug)
 #
 #  ====================================================================
 #  Example:
@@ -20,7 +36,7 @@
 #   include_directories(${CMAKE_CURRENT_BINARY_DIR})
 #   PROTOBUF_GENERATE_CPP(PROTO_SRCS PROTO_HDRS foo.proto)
 #   add_executable(bar bar.cc ${PROTO_SRCS} ${PROTO_HDRS})
-#   target_link_libraries(bar ${PROTOBUF_LIBRARY})
+#   target_link_libraries(bar ${PROTOBUF_LIBRARIES})
 #
 # NOTE: You may need to link against pthreads, depending
 # on the platform.
@@ -38,7 +54,7 @@
 
 #=============================================================================
 # Copyright 2009 Kitware, Inc.
-# Copyright 2009 Philip Lowman <[email protected]>
+# Copyright 2009,2011 Philip Lowman <[email protected]>
 # Copyright 2008 Esben Mose Hansen, Ange Optimization ApS
 #
 # Distributed under the OSI-approved BSD License (the "License");
@@ -81,41 +97,85 @@ function(PROTOBUF_GENERATE_CPP SRCS HDRS)
   set(${HDRS} ${${HDRS}} PARENT_SCOPE)
 endfunction()
 
+# Internal function: search for normal library as well as a debug one
+#    if the debug one is specified also include debug/optimized keywords
+#    in *_LIBRARIES variable
+function(_protobuf_find_libraries name filename)
+   find_library(${name}_LIBRARY
+       NAMES ${filename}
+       PATHS ${PROTOBUF_SRC_ROOT_FOLDER}/vsprojects/Release)
+   mark_as_advanced(${name}_LIBRARY)
+
+   find_library(${name}_LIBRARY_DEBUG
+       NAMES ${filename}
+       PATHS ${PROTOBUF_SRC_ROOT_FOLDER}/vsprojects/Debug)
+   mark_as_advanced(${name}_LIBRARY_DEBUG)
+
+   if(NOT ${name}_LIBRARY_DEBUG)
+      # There is no debug library
+      set(${name}_LIBRARY_DEBUG ${${name}_LIBRARY} PARENT_SCOPE)
+      set(${name}_LIBRARIES     ${${name}_LIBRARY} PARENT_SCOPE)
+   else()
+      # There IS a debug library
+      set(${name}_LIBRARIES
+          optimized ${${name}_LIBRARY}
+          debug     ${${name}_LIBRARY_DEBUG}
+          PARENT_SCOPE
+      )
+   endif()
+endfunction()
+
 
-find_path(PROTOBUF_INCLUDE_DIR google/protobuf/service.h)
+#
+# Main.
+#
 
 # Google's provided vcproj files generate libraries with a "lib"
 # prefix on Windows
-if(WIN32)
+if(MSVC)
     set(PROTOBUF_ORIG_FIND_LIBRARY_PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
     set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "")
+
+    find_path(PROTOBUF_SRC_ROOT_FOLDER protobuf.pc.in)
 endif()
 
-find_library(PROTOBUF_LIBRARY NAMES protobuf
-             DOC "The Google Protocol Buffers Library"
-)
-find_library(PROTOBUF_PROTOC_LIBRARY NAMES protoc
-             DOC "The Google Protocol Buffers Compiler Library"
-)
-find_program(PROTOBUF_PROTOC_EXECUTABLE NAMES protoc
-             DOC "The Google Protocol Buffers Compiler"
-)
+# The Protobuf library
+_protobuf_find_libraries(PROTOBUF protobuf)
+#DOC "The Google Protocol Buffers RELEASE Library"
 
-mark_as_advanced(PROTOBUF_INCLUDE_DIR
-                 PROTOBUF_LIBRARY
-                 PROTOBUF_PROTOC_LIBRARY
-                 PROTOBUF_PROTOC_EXECUTABLE)
+_protobuf_find_libraries(PROTOBUF_LITE protobuf-lite)
+
+# The Protobuf Protoc Library
+_protobuf_find_libraries(PROTOBUF_PROTOC protoc)
 
 # Restore original find library prefixes
-if(WIN32)
+if(MSVC)
     set(CMAKE_FIND_LIBRARY_PREFIXES "${PROTOBUF_ORIG_FIND_LIBRARY_PREFIXES}")
 endif()
 
+
+# Find the include directory
+find_path(PROTOBUF_INCLUDE_DIR
+    google/protobuf/service.h
+    PATHS ${PROTOBUF_SRC_ROOT_FOLDER}/src
+)
+mark_as_advanced(PROTOBUF_INCLUDE_DIR)
+
+# Find the protoc Executable
+find_program(PROTOBUF_PROTOC_EXECUTABLE
+    NAMES protoc
+    DOC "The Google Protocol Buffers Compiler"
+    PATHS
+    ${PROTOBUF_SRC_ROOT_FOLDER}/vsprojects/Release
+    ${PROTOBUF_SRC_ROOT_FOLDER}/vsprojects/Debug
+)
+mark_as_advanced(PROTOBUF_PROTOC_EXECUTABLE)
+
+
 include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
 FIND_PACKAGE_HANDLE_STANDARD_ARGS(PROTOBUF DEFAULT_MSG
     PROTOBUF_LIBRARY PROTOBUF_INCLUDE_DIR)
 
 if(PROTOBUF_FOUND)
     set(PROTOBUF_INCLUDE_DIRS ${PROTOBUF_INCLUDE_DIR})
-    set(PROTOBUF_LIBRARIES    ${PROTOBUF_LIBRARY})
 endif()