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davidt315David Tarazi
davidt315
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David Tarazi
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added an EXPORT arg to allow for exporting for other packages to use (#3)
Enables dbc_cpp_gen to exist in a DBC package, then the hpp files can be used by an external package importing the dbc package --------- Co-authored-by: David Tarazi <david@polymathrobotics.com>
1 parent e7748fb commit 3ec62bd

3 files changed

Lines changed: 100 additions & 28 deletions

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‎dbc_gen_cpp/cmake/generate_dbc_cpp.cmake‎

Lines changed: 55 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -1,57 +1,84 @@
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# SPDX-FileCopyrightText: 2026 Polymath Robotics, Inc.
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# SPDX-License-Identifier: Apache-2.0
3-
function(generate_dbc_cpp library_name)
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#
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# generate_dbc_cpp(<library_name> DBC <path/to/file.dbc>)
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#
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# Generates C/C++ CAN message types from a DBC file and builds them into a static
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# library named <library_name> (C++ namespace and C-symbol prefix also <library_name>,
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# headers at include/<library_name>/<library_name>.hpp).
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#
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# The library is ALWAYS installed and exported, so a downstream package that does
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# find_package(<this_package>) can link it as the imported target
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# <this_package>::<library_name>. Within the generating package it is also usable by
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# its plain local name.
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#
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# NOTE: this is a macro, not a function, on purpose. It calls ament_export_targets()
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# and ament_export_dependencies(), whose bookkeeping is stored in ordinary variables
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# in the current scope; ament_package() reads them from the package's top-level scope,
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# so they must not be trapped inside a function scope.
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macro(generate_dbc_cpp library_name)
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find_package(Python3 REQUIRED COMPONENTS Interpreter)
521

6-
set(one_value_args DBC)
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cmake_parse_arguments(ARG "" "${one_value_args}" "" ${ARGN})
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if(NOT ARG_DBC)
22+
cmake_parse_arguments(_dbc_arg "" "DBC" "" ${ARGN})
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if(NOT _dbc_arg_DBC)
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message(FATAL_ERROR "generate_dbc_cpp: Missing required keyword argument DBC")
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endif()
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12-
set(gen_basedir ${CMAKE_CURRENT_BINARY_DIR}/dbc_gen_cpp)
13-
set(gen_dir ${gen_basedir}/${library_name})
27+
set(_dbc_gen_basedir ${CMAKE_CURRENT_BINARY_DIR}/dbc_gen_cpp)
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set(_dbc_gen_dir ${_dbc_gen_basedir}/${library_name})
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15-
set(generated_c ${gen_dir}/${library_name}.c)
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set(generated_h ${gen_dir}/${library_name}.h)
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set(generated_hpp ${gen_dir}/${library_name}.hpp)
18-
set(generated_files ${generated_c} ${generated_h} ${generated_hpp})
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set(_dbc_generated_c ${_dbc_gen_dir}/${library_name}.c)
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set(_dbc_generated_h ${_dbc_gen_dir}/${library_name}.h)
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set(_dbc_generated_hpp ${_dbc_gen_dir}/${library_name}.hpp)
1933

20-
# Kind of awkward, but makes the sources get regenerated if the generator tool changes, by depending on the generator sources.
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# Finds the python module directory via Python3 import
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# Kind of awkward, but makes the sources get regenerated if the generator tool
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# changes, by depending on the generator sources. Finds the python module directory.
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execute_process(
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COMMAND ${Python3_EXECUTABLE} -c "import dbc_gen_cpp, os; print(os.path.dirname(dbc_gen_cpp.__file__))"
24-
OUTPUT_VARIABLE GENERATOR_DIR
38+
OUTPUT_VARIABLE _dbc_generator_dir
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OUTPUT_STRIP_TRAILING_WHITESPACE
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)
27-
file(GLOB_RECURSE GENERATOR_SOURCES CONFIGURE_DEPENDS
28-
"${GENERATOR_DIR}/*.py"
29-
"${GENERATOR_DIR}/templates/*.j2"
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file(GLOB_RECURSE _dbc_generator_sources CONFIGURE_DEPENDS
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"${_dbc_generator_dir}/*.py"
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"${_dbc_generator_dir}/templates/*.j2"
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)
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32-
# Generate the source files
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# Generate the source files.
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add_custom_command(
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OUTPUT ${generated_files}
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COMMAND ${Python3_EXECUTABLE} -m dbc_gen_cpp ${ARG_DBC} -o ${gen_dir} -n ${library_name}
36-
DEPENDS ${ARG_DBC} ${GENERATOR_SOURCES}
37-
COMMENT "Generating C source from DBC ${ARG_DBC} with cantools"
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OUTPUT ${_dbc_generated_c} ${_dbc_generated_h} ${_dbc_generated_hpp}
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COMMAND ${Python3_EXECUTABLE} -m dbc_gen_cpp ${_dbc_arg_DBC} -o ${_dbc_gen_dir} -n ${library_name}
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DEPENDS ${_dbc_arg_DBC} ${_dbc_generator_sources}
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COMMENT "Generating C source from DBC ${_dbc_arg_DBC} with cantools"
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VERBATIM
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)
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add_custom_target(${library_name}_c_sources
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DEPENDS ${generated_c} ${generated_h}
55+
DEPENDS ${_dbc_generated_c} ${_dbc_generated_h}
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)
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44-
# Create the library target from generated sources
45-
add_library(${library_name} STATIC ${generated_c})
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# Create the library target from generated sources.
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add_library(${library_name} STATIC ${_dbc_generated_c})
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add_dependencies(${library_name} ${library_name}_c_sources)
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target_link_libraries(${library_name} PUBLIC dbc_gen_cpp::dbc_gen_cpp)
4862
target_include_directories(${library_name}
49-
PUBLIC ${gen_basedir}
63+
PUBLIC
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$<BUILD_INTERFACE:${_dbc_gen_basedir}>
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$<INSTALL_INTERFACE:include>
5066
)
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52-
# Install the generated files to the install space, just in case they're included in public headers
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# Install + export the target and its headers so other packages can link it as
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# <this_package>::${library_name}.
5370
install(
54-
FILES ${generated_h} ${generated_hpp}
71+
TARGETS ${library_name}
72+
EXPORT ${library_name}Targets
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ARCHIVE DESTINATION lib
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LIBRARY DESTINATION lib
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RUNTIME DESTINATION bin
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INCLUDES DESTINATION include
77+
)
78+
install(
79+
FILES ${_dbc_generated_h} ${_dbc_generated_hpp}
5580
DESTINATION include/${library_name}
5681
)
57-
endfunction()
82+
ament_export_targets(${library_name}Targets HAS_LIBRARY_TARGET)
83+
ament_export_dependencies(dbc_gen_cpp)
84+
endmacro()

‎test_dbc_gen_cpp/CMakeLists.txt‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,20 @@ if(BUILD_TESTING)
4848
ENV CATCH_CONFIG_CONSOLE_WIDTH=120
4949
WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
5050
)
51+
52+
# Verify that generate_dbc_cpp() installs the generated headers into the export
53+
# location (include/<library_name>/) so downstream packages can consume them.
54+
# This exercises the install/export path, which the compiled test above does not:
55+
# that test links the libraries in-tree via their BUILD_INTERFACE include dirs.
56+
ament_add_test(
57+
test_dbc_exported_headers
58+
GENERATE_RESULT_FOR_RETURN_CODE_ZERO
59+
COMMAND ${CMAKE_COMMAND}
60+
-DINSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
61+
"-DLIBRARIES=fake_vehicle_can;fake_j1939_can"
62+
-P ${CMAKE_CURRENT_SOURCE_DIR}/test/check_exported_headers.cmake
63+
WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
64+
)
5165
endif()
5266

5367
ament_package()

‎test_dbc_gen_cpp/test/check_exported_headers.cmake‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
1+
# SPDX-FileCopyrightText: 2026 Polymath Robotics, Inc.
2+
# SPDX-License-Identifier: Apache-2.0
3+
#
4+
# Verifies that generate_dbc_cpp() exports the generated headers into the install
5+
# space so downstream packages can include them as <library_name>/<library_name>.hpp.
6+
#
7+
# Invoked with -DINSTALL_PREFIX=<prefix> -DLIBRARIES=<lib1;lib2>.
8+
9+
if(NOT DEFINED INSTALL_PREFIX)
10+
message(FATAL_ERROR "check_exported_headers: INSTALL_PREFIX not set")
11+
endif()
12+
if(NOT DEFINED LIBRARIES)
13+
message(FATAL_ERROR "check_exported_headers: LIBRARIES not set")
14+
endif()
15+
16+
set(_missing "")
17+
foreach(_lib IN LISTS LIBRARIES)
18+
foreach(_ext h hpp)
19+
set(_header "${INSTALL_PREFIX}/include/${_lib}/${_lib}.${_ext}")
20+
if(EXISTS "${_header}")
21+
message(STATUS "Found exported header: ${_header}")
22+
else()
23+
message(WARNING "Missing exported header: ${_header}")
24+
list(APPEND _missing "${_header}")
25+
endif()
26+
endforeach()
27+
endforeach()
28+
29+
if(_missing)
30+
message(FATAL_ERROR "generate_dbc_cpp did not export the expected headers:\n ${_missing}")
31+
endif()

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