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      1 # Copyright 2015 Google Inc. All rights reserved.
      2 #
      3 # Licensed under the Apache License, Version 2.0 (the "License");
      4 # you may not use this file except in compliance with the License.
      5 # You may obtain a copy of the License at
      6 #
      7 #     http://www.apache.org/licenses/LICENSE-2.0
      8 #
      9 # Unless required by applicable law or agreed to in writing, software
     10 # distributed under the License is distributed on an "AS IS" BASIS,
     11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 # See the License for the specific language governing permissions and
     13 # limitations under the License.
     14 
     15 # General function to create FlatBuffer build rules for the given list of
     16 # schemas.
     17 #
     18 # flatbuffers_schemas: A list of flatbuffer schema files to process.
     19 #
     20 # schema_include_dirs: A list of schema file include directories, which will be
     21 # passed to flatc via the -I parameter.
     22 #
     23 # custom_target_name: The generated files will be added as dependencies for a
     24 # new custom target with this name. You should add that target as a dependency
     25 # for your main target to ensure these files are built. You can also retrieve
     26 # various properties from this target, such as GENERATED_INCLUDES_DIR,
     27 # BINARY_SCHEMAS_DIR, and COPY_TEXT_SCHEMAS_DIR.
     28 #
     29 # additional_dependencies: A list of additional dependencies that you'd like
     30 # all generated files to depend on. Pass in a blank string if you have none.
     31 #
     32 # generated_includes_dir: Where to generate the C++ header files for these
     33 # schemas. The generated includes directory will automatically be added to
     34 # CMake's include directories, and will be where generated header files are
     35 # placed. This parameter is optional; pass in empty string if you don't want to
     36 # generate include files for these schemas.
     37 #
     38 # binary_schemas_dir: If you specify an optional binary schema directory, binary
     39 # schemas will be generated for these schemas as well, and placed into the given
     40 # directory.
     41 #
     42 # copy_text_schemas_dir: If you want all text schemas (including schemas from
     43 # all schema include directories) copied into a directory (for example, if you
     44 # need them within your project to build JSON files), you can specify that
     45 # folder here. All text schemas will be copied to that folder.
     46 #
     47 # IMPORTANT: Make sure you quote all list arguments you pass to this function!
     48 # Otherwise CMake will only pass in the first element.
     49 # Example: build_flatbuffers("${fb_files}" "${include_dirs}" target_name ...)
     50 function(build_flatbuffers flatbuffers_schemas
     51                            schema_include_dirs
     52                            custom_target_name
     53                            additional_dependencies
     54                            generated_includes_dir
     55                            binary_schemas_dir
     56                            copy_text_schemas_dir)
     57 
     58   # Test if including from FindFlatBuffers
     59   if(FLATBUFFERS_FLATC_EXECUTABLE)
     60     set(FLATC_TARGET "")
     61     set(FLATC ${FLATBUFFERS_FLATC_EXECUTABLE})
     62   else()
     63     set(FLATC_TARGET flatc)
     64     set(FLATC flatc)
     65   endif()
     66   set(FLATC_SCHEMA_ARGS --gen-mutable)
     67   if(FLATBUFFERS_FLATC_SCHEMA_EXTRA_ARGS)
     68     set(FLATC_SCHEMA_ARGS
     69       ${FLATBUFFERS_FLATC_SCHEMA_EXTRA_ARGS}
     70       ${FLATC_SCHEMA_ARGS}
     71       )
     72   endif()
     73 
     74   set(working_dir "${CMAKE_CURRENT_SOURCE_DIR}")
     75 
     76   set(schema_glob "*.fbs")
     77   # Generate the include files parameters.
     78   set(include_params "")
     79   set(all_generated_files "")
     80   foreach (include_dir ${schema_include_dirs})
     81     set(include_params -I ${include_dir} ${include_params})
     82     if (NOT ${copy_text_schemas_dir} STREQUAL "")
     83       # Copy text schemas from dependent folders.
     84       file(GLOB_RECURSE dependent_schemas ${include_dir}/${schema_glob})
     85       foreach (dependent_schema ${dependent_schemas})
     86         file(COPY ${dependent_schema} DESTINATION ${copy_text_schemas_dir})
     87       endforeach()
     88     endif()
     89   endforeach()
     90 
     91   foreach(schema ${flatbuffers_schemas})
     92     get_filename_component(filename ${schema} NAME_WE)
     93     # For each schema, do the things we requested.
     94     if (NOT ${generated_includes_dir} STREQUAL "")
     95       set(generated_include ${generated_includes_dir}/${filename}_generated.h)
     96       add_custom_command(
     97         OUTPUT ${generated_include}
     98         COMMAND ${FLATC} ${FLATC_SCHEMA_ARGS}
     99         -o ${generated_includes_dir}
    100         ${include_params}
    101         -c ${schema}
    102         DEPENDS ${FLATC_TARGET} ${schema} ${additional_dependencies}
    103         WORKING_DIRECTORY "${working_dir}")
    104       list(APPEND all_generated_files ${generated_include})
    105     endif()
    106 
    107     if (NOT ${binary_schemas_dir} STREQUAL "")
    108       set(binary_schema ${binary_schemas_dir}/${filename}.bfbs)
    109       add_custom_command(
    110         OUTPUT ${binary_schema}
    111         COMMAND ${FLATC} -b --schema
    112         -o ${binary_schemas_dir}
    113         ${include_params}
    114         ${schema}
    115         DEPENDS ${FLATC_TARGET} ${schema} ${additional_dependencies}
    116         WORKING_DIRECTORY "${working_dir}")
    117       list(APPEND all_generated_files ${binary_schema})
    118     endif()
    119 
    120     if (NOT ${copy_text_schemas_dir} STREQUAL "")
    121       file(COPY ${schema} DESTINATION ${copy_text_schemas_dir})
    122     endif()
    123   endforeach()
    124 
    125   # Create a custom target that depends on all the generated files.
    126   # This is the target that you can depend on to trigger all these
    127   # to be built.
    128   add_custom_target(${custom_target_name}
    129                     DEPENDS ${all_generated_files} ${additional_dependencies})
    130 
    131   # Register the include directory we are using.
    132   if (NOT ${generated_includes_dir} STREQUAL "")
    133     include_directories(${generated_includes_dir})
    134     set_property(TARGET ${custom_target_name}
    135       PROPERTY GENERATED_INCLUDES_DIR
    136       ${generated_includes_dir})
    137   endif()
    138 
    139   # Register the binary schemas dir we are using.
    140   if (NOT ${binary_schemas_dir} STREQUAL "")
    141     set_property(TARGET ${custom_target_name}
    142       PROPERTY BINARY_SCHEMAS_DIR
    143       ${binary_schemas_dir})
    144   endif()
    145 
    146   # Register the text schema copy dir we are using.
    147   if (NOT ${copy_text_schemas_dir} STREQUAL "")
    148     set_property(TARGET ${custom_target_name}
    149       PROPERTY COPY_TEXT_SCHEMAS_DIR
    150       ${copy_text_schemas_dir})
    151   endif()
    152 endfunction()
    153