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path: root/sdk/compiler/cmake/modules/CapnProtoGenerate.cmake
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# Configuration variables (optional):
#   CAPNPC_OUTPUT_DIR
#       Directory to place compiled schema sources (default: the same directory as the schema file).
#   CAPNPC_IMPORT_DIRS
#       List of additional include directories for the schema compiler.
#       (CMAKE_CURRENT_SOURCE_DIR and CAPNP_INCLUDE_DIRS are always included.)
#   CAPNPC_SRC_PREFIX
#       Schema file source prefix (default: CMAKE_CURRENT_SOURCE_DIR).
#   CAPNPC_FLAGS
#       Additional flags to pass to the schema compiler.
# Example usage:
#
#   capnp_generate_cpp(CAPNP_SRCS CAPNP_HDRS schema.capnp)
#   add_executable(a a.cc ${CAPNP_SRCS} ${CAPNP_HDRS})
#   target_link_library(a ${CAPNP_LIBRARIES})
#
# For out-of-source builds:
#
#   set(CAPNPC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR})
#   include_directories(${CAPNPC_OUTPUT_DIR})
#   capnp_generate_cpp(...)

function(CAPNP_GENERATE_CPP SOURCES HEADERS)
  if(NOT ARGN)
    message(SEND_ERROR "CAPNP_GENERATE_CPP() called without any source files.")
  endif()
  if(NOT CAPNP_EXECUTABLE)
    message(SEND_ERROR "Could not locate capnp executable (CAPNP_EXECUTABLE).")
  endif()
  if(NOT CAPNPC_CXX_EXECUTABLE)
    message(SEND_ERROR "Could not locate capnpc-c++ executable (CAPNPC_CXX_EXECUTABLE).")
  endif()
  if(NOT CAPNP_INCLUDE_DIRS)
    message(SEND_ERROR "Could not locate capnp header files (CAPNP_INCLUDE_DIRS).")
  endif()

  # Default compiler includes
  set(include_path -I ${CMAKE_CURRENT_SOURCE_DIR} -I ${CAPNP_INCLUDE_DIRS})

  if(DEFINED CAPNPC_IMPORT_DIRS)
    # Append each directory as a series of '-I' flags in ${include_path}
    foreach(directory ${CAPNPC_IMPORT_DIRS})
      get_filename_component(absolute_path "${directory}" ABSOLUTE)
      list(APPEND include_path -I ${absolute_path})
    endforeach()
  endif()

  if(DEFINED CAPNPC_OUTPUT_DIR)
    set(output_dir "${CAPNPC_OUTPUT_DIR}")
  else()
    set(output_dir ".")
  endif()

  if(NOT DEFINED CAPNPC_SRC_PREFIX)
    set(CAPNPC_SRC_PREFIX "${CMAKE_CURRENT_SOURCE_DIR}")
  endif()
  get_filename_component(CAPNPC_SRC_PREFIX "${CAPNPC_SRC_PREFIX}" ABSOLUTE)

  set(${SOURCES})
  set(${HEADERS})
  foreach(schema_file ${ARGN})
    get_filename_component(file_path "${schema_file}" ABSOLUTE)
    get_filename_component(file_dir "${file_path}" PATH)

    # Figure out where the output files will go
    if (NOT DEFINED CAPNPC_OUTPUT_DIR)
      set(output_base "${file_path}")
    else()
      # Output files are placed in CAPNPC_OUTPUT_DIR, at a location as if they were
      # relative to CAPNPC_SRC_PREFIX.
      string(LENGTH "${CAPNPC_SRC_PREFIX}" prefix_len)
      string(SUBSTRING "${file_path}" 0 ${prefix_len} output_prefix)
      if(NOT "${CAPNPC_SRC_PREFIX}" STREQUAL "${output_prefix}")
        message(SEND_ERROR "Could not determine output path for '${schema_file}' ('${file_path}') with source prefix '${CAPNPC_SRC_PREFIX}' into '${CAPNPC_OUTPUT_DIR}'.")
      endif()

      string(SUBSTRING "${file_path}" ${prefix_len} -1 output_path)
      set(output_base "${CAPNPC_OUTPUT_DIR}${output_path}")
    endif()

    MESSAGE("Output base: " ${output_base})
    MESSAGE("Output path: " ${output_path})
    MESSAGE("Output dir: " ${output_dir})
    MESSAGE("Src prefix: " ${CAPNPC_SRC_PREFIX})

    add_custom_command(
      OUTPUT "${output_base}.c++" "${output_base}.h"
      COMMAND ${CMAKE_COMMAND} -E make_directory ${output_dir}
      COMMAND "${CAPNP_EXECUTABLE}"
      ARGS compile 
          -o ${CAPNPC_CXX_EXECUTABLE}:${output_dir}
          --verbose
          --src-prefix ${CAPNPC_SRC_PREFIX}
          ${include_path}
          ${CAPNPC_FLAGS}
          ${file_path}
      DEPENDS "${schema_file}"
      COMMENT "Compiling Cap'n Proto schema ${schema_file}"
      VERBATIM
    )
    list(APPEND ${SOURCES} "${output_base}.c++")
    list(APPEND ${HEADERS} "${output_base}.h")
  endforeach()

  set_source_files_properties(${${SOURCES}} ${${HEADERS}} PROPERTIES GENERATED TRUE)
  set(${SOURCES} ${${SOURCES}} PARENT_SCOPE)
  set(${HEADERS} ${${HEADERS}} PARENT_SCOPE)
endfunction()