flatbuffers/cmake: move build_flatbuffers to a standalone file

So that it could be included from both flatbuffers CMakeLists.txt and
FindFlatBuffers.cmake.

Change-Id: Ie16a879beef9367cd6fd9b2d2157044841a7cdbc

CMake/BuildFlatBuffers.cmake

+# Copyright 2015 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# General function to create FlatBuffer build rules for the given list of
+# schemas.
+#
+# flatbuffers_schemas: A list of flatbuffer schema files to process.
+#
+# schema_include_dirs: A list of schema file include directories, which will be
+# passed to flatc via the -I parameter.
+#
+# custom_target_name: The generated files will be added as dependencies for a
+# new custom target with this name. You should add that target as a dependency
+# for your main target to ensure these files are built. You can also retrieve
+# various properties from this target, such as GENERATED_INCLUDES_DIR,
+# BINARY_SCHEMAS_DIR, and COPY_TEXT_SCHEMAS_DIR.
+#
+# additional_dependencies: A list of additional dependencies that you'd like
+# all generated files to depend on. Pass in a blank string if you have none.
+#
+# generated_includes_dir: Where to generate the C++ header files for these
+# schemas. The generated includes directory will automatically be added to
+# CMake's include directories, and will be where generated header files are
+# placed. This parameter is optional; pass in empty string if you don't want to
+# generate include files for these schemas.
+#
+# binary_schemas_dir: If you specify an optional binary schema directory, binary
+# schemas will be generated for these schemas as well, and placed into the given
+# directory.
+#
+# copy_text_schemas_dir: If you want all text schemas (including schemas from
+# all schema include directories) copied into a directory (for example, if you
+# need them within your project to build JSON files), you can specify that
+# folder here. All text schemas will be copied to that folder.
+#
+# IMPORTANT: Make sure you quote all list arguments you pass to this function!
+# Otherwise CMake will only pass in the first element.
+# Example: build_flatbuffers("${fb_files}" "${include_dirs}" target_name ...)
+function(build_flatbuffers flatbuffers_schemas
+                           schema_include_dirs
+                           custom_target_name
+                           additional_dependencies
+                           generated_includes_dir
+                           binary_schemas_dir
+                           copy_text_schemas_dir)
+
+  # Test if including from FindFlatBuffers
+  if(FLATBUFFERS_FLATC_EXECUTABLE)
+    set(FLATC_TARGET "")
+    set(FLATC ${FLATBUFFERS_FLATC_EXECUTABLE})
+  else()
+    set(FLATC_TARGET flatc)
+    set(FLATC flatc)
+  endif()
+
+  set(schema_glob "*.fbs")
+  # Generate the include files parameters.
+  set(include_params "")
+  set(all_generated_files "")
+  foreach (include_dir ${schema_include_dirs})
+    set(include_params -I ${include_dir} ${include_params})
+    if (NOT ${copy_text_schemas_dir} STREQUAL "")
+      # Copy text schemas from dependent folders.
+      file(GLOB_RECURSE dependent_schemas ${include_dir}/${schema_glob})
+      foreach (dependent_schema ${dependent_schemas})
+        file(COPY ${dependent_schema} DESTINATION ${copy_text_schemas_dir})
+      endforeach()
+    endif()
+  endforeach()
+
+  foreach(schema ${flatbuffers_schemas})
+    get_filename_component(filename ${schema} NAME_WE)
+    # For each schema, do the things we requested.
+    if (NOT ${generated_includes_dir} STREQUAL "")
+      set(generated_include ${generated_includes_dir}/${filename}_generated.h)
+      add_custom_command(
+        OUTPUT ${generated_include}
+        COMMAND ${FLATC} --gen-mutable
+        -o ${generated_includes_dir}
+        ${include_params}
+        -c ${schema}
+        DEPENDS ${FLATC_TARGET} ${schema} ${additional_dependencies})
+      list(APPEND all_generated_files ${generated_include})
+    endif()
+
+    if (NOT ${binary_schemas_dir} STREQUAL "")
+      set(binary_schema ${binary_schemas_dir}/${filename}.bfbs)
+      add_custom_command(
+        OUTPUT ${binary_schema}
+        COMMAND ${FLATC} -b --schema
+        -o ${binary_schemas_dir}
+        ${include_params}
+        ${schema}
+        DEPENDS ${FLATC_TARGET} ${schema} ${additional_dependencies})
+      list(APPEND all_generated_files ${binary_schema})
+    endif()
+
+    if (NOT ${copy_text_schemas_dir} STREQUAL "")
+      file(COPY ${schema} DESTINATION ${copy_text_schemas_dir})
+    endif()
+  endforeach()
+
+  # Create a custom target that depends on all the generated files.
+  # This is the target that you can depend on to trigger all these
+  # to be built.
+  add_custom_target(${custom_target_name}
+                    DEPENDS ${all_generated_files} ${additional_dependencies})
+
+  # Register the include directory we are using.
+  if (NOT ${generated_includes_dir} STREQUAL "")
+    include_directories(${generated_includes_dir})
+    set_property(TARGET ${custom_target_name}
+      PROPERTY GENERATED_INCLUDES_DIR
+      ${generated_includes_dir})
+  endif()
+
+  # Register the binary schemas dir we are using.
+  if (NOT ${binary_schemas_dir} STREQUAL "")
+    set_property(TARGET ${custom_target_name}
+      PROPERTY BINARY_SCHEMAS_DIR
+      ${binary_schemas_dir})
+  endif()
+
+  # Register the text schema copy dir we are using.
+  if (NOT ${copy_text_schemas_dir} STREQUAL "")
+    set_property(TARGET ${custom_target_name}
+      PROPERTY COPY_TEXT_SCHEMAS_DIR
+      ${copy_text_schemas_dir})
+  endif()
+endfunction()

CMake/FindFlatBuffers.cmake

@@ -24,6 +24,8 @@
 #   for the given flatbuffer schema files.
 #   Returns the header files in ${Name}_OUTPUTS
 
+set(FLATBUFFERS_CMAKE_DIR ${CMAKE_CURRENT_LIST_DIR})
+
 find_program(FLATBUFFERS_FLATC_EXECUTABLE NAMES flatc)
 find_path(FLATBUFFERS_INCLUDE_DIR NAMES flatbuffers/flatbuffers.h)
 
@@ -54,3 +56,5 @@ if(FLATBUFFERS_FOUND)
 else()
   set(FLATBUFFERS_INCLUDE_DIR)
 endif()
+
+include("${FLATBUFFERS_CMAKE_DIR}/BuildFlatBuffers.cmake")
\ No newline at end of file

CMakeLists.txt

@@ -129,124 +129,6 @@ function(compile_flatbuffers_schema_to_binary SRC_FBS)
     DEPENDS flatc)
 endfunction()
 
-# General function to create FlatBuffer build rules for the given list of
-# schemas.
-#
-# flatbuffers_schemas: A list of flatbuffer schema files to process.
-#
-# schema_include_dirs: A list of schema file include directories, which will be
-# passed to flatc via the -I parameter.
-#
-# custom_target_name: The generated files will be added as dependencies for a
-# new custom target with this name. You should add that target as a dependency
-# for your main target to ensure these files are built. You can also retrieve
-# various properties from this target, such as GENERATED_INCLUDES_DIR,
-# BINARY_SCHEMAS_DIR, and COPY_TEXT_SCHEMAS_DIR.
-#
-# additional_dependencies: A list of additional dependencies that you'd like
-# all generated files to depend on. Pass in a blank string if you have none.
-#
-# generated_includes_dir: Where to generate the C++ header files for these
-# schemas. The generated includes directory will automatically be added to
-# CMake's include directories, and will be where generated header files are
-# placed. This parameter is optional; pass in empty string if you don't want to
-# generate include files for these schemas.
-#
-# binary_schemas_dir: If you specify an optional binary schema directory, binary
-# schemas will be generated for these schemas as well, and placed into the given
-# directory.
-#
-# copy_text_schemas_dir: If you want all text schemas (including schemas from
-# all schema include directories) copied into a directory (for example, if you
-# need them within your project to build JSON files), you can specify that
-# folder here. All text schemas will be copied to that folder.
-#
-# IMPORTANT: Make sure you quote all list arguments you pass to this function!
-# Otherwise CMake will only pass in the first element.
-# Example: build_flatbuffers("${fb_files}" "${include_dirs}" target_name ...)
-function(build_flatbuffers flatbuffers_schemas
-                           schema_include_dirs
-                           custom_target_name
-                           additional_dependencies
-                           generated_includes_dir
-                           binary_schemas_dir
-                           copy_text_schemas_dir)
-  set(schema_glob "*.fbs")
-  # Generate the include files parameters.
-  set(include_params "")
-  set(all_generated_files "")
-  foreach (include_dir ${schema_include_dirs})
-    set(include_params -I ${include_dir} ${include_params})
-    if (NOT ${copy_text_schemas_dir} STREQUAL "")
-      # Copy text schemas from dependent folders.
-      file(GLOB_RECURSE dependent_schemas ${include_dir}/${schema_glob})
-      foreach (dependent_schema ${dependent_schemas})
-        file(COPY ${dependent_schema} DESTINATION ${copy_text_schemas_dir})
-      endforeach()
-    endif()
-  endforeach()
-
-  foreach(schema ${flatbuffers_schemas})
-    get_filename_component(filename ${schema} NAME_WE)
-    # For each schema, do the things we requested.
-    if (NOT ${generated_includes_dir} STREQUAL "")
-      set(generated_include ${generated_includes_dir}/${filename}_generated.h)
-      add_custom_command(
-        OUTPUT ${generated_include}
-        COMMAND flatc --gen-mutable
-        -o ${generated_includes_dir}
-        ${include_params}
-        -c ${schema}
-        DEPENDS flatc ${schema} ${additional_dependencies})
-      list(APPEND all_generated_files ${generated_include})
-    endif()
-
-    if (NOT ${binary_schemas_dir} STREQUAL "")
-      set(binary_schema ${binary_schemas_dir}/${filename}.bfbs)
-      add_custom_command(
-        OUTPUT ${binary_schema}
-        COMMAND flatc -b --schema
-        -o ${binary_schemas_dir}
-        ${include_params}
-        ${schema}
-        DEPENDS flatc ${schema} ${additional_dependencies})
-      list(APPEND all_generated_files ${binary_schema})
-    endif()
-
-    if (NOT ${copy_text_schemas_dir} STREQUAL "")
-      file(COPY ${schema} DESTINATION ${copy_text_schemas_dir})
-    endif()
-  endforeach()
-
-  # Create a custom target that depends on all the generated files.
-  # This is the target that you can depend on to trigger all these
-  # to be built.
-  add_custom_target(${custom_target_name}
-                    DEPENDS ${all_generated_files} ${additional_dependencies})
-
-  # Register the include directory we are using.
-  if (NOT ${generated_includes_dir} STREQUAL "")
-    include_directories(${generated_includes_dir})
-    set_property(TARGET ${custom_target_name}
-      PROPERTY GENERATED_INCLUDES_DIR
-      ${generated_includes_dir})
-  endif()
-
-  # Register the binary schemas dir we are using.
-  if (NOT ${binary_schemas_dir} STREQUAL "")
-    set_property(TARGET ${custom_target_name}
-      PROPERTY BINARY_SCHEMAS_DIR
-      ${binary_schemas_dir})
-  endif()
-
-  # Register the text schema copy dir we are using.
-  if (NOT ${copy_text_schemas_dir} STREQUAL "")
-    set_property(TARGET ${custom_target_name}
-      PROPERTY COPY_TEXT_SCHEMAS_DIR
-      ${copy_text_schemas_dir})
-  endif()
-endfunction()
-
 if(FLATBUFFERS_BUILD_TESTS)
   compile_flatbuffers_schema_to_cpp(tests/monster_test.fbs)
   include_directories(${CMAKE_CURRENT_BINARY_DIR}/tests)
@@ -275,3 +157,5 @@ if(FLATBUFFERS_BUILD_TESTS)
        "${CMAKE_CURRENT_BINARY_DIR}")
   add_test(NAME flattests COMMAND flattests)
 endif()
+
+include(CMake/BuildFlatBuffers.cmake)