Postprocessing and preprocessing

Header preprocessing

If you need to preprocess header code before the generation, you can create a function that transforms the source code, and store it inside options.srcmlcpp_options.code_preprocess_function

For example:

def preprocess_change_int(code: str) -> str:
    return code.replace("int", "Int32")  # This is a *very* dumb preprocessor


cpp_code = """
int add(int, int b);
"""

import litgen
from litgen.demo import litgen_demo

options = litgen.LitgenOptions()
options.srcmlcpp_options.code_preprocess_function = preprocess_change_int
litgen_demo.demo(options, cpp_code)

Original C++ decls

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int add(int, int b);

Corresponding python decls (stub)

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def add(param_0: Int32, b: Int32) -> Int32:
    pass

pybind11 C++ binding code

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m.def("add",
    add, py::arg("param_0"), py::arg("b"));

nanobind C++ binding code

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m.def("add",
    add, nb::arg("param_0"), nb::arg("b"));

Post-processing of the stub and pydef files

You can also post-process the stub and pydef files, i.e. apply a function that will be called after the code is generated. Below is a very dumb example:

cpp_code = """
int AnswerToTheUltimateQuestionOfLife_TheUniverse_AndEverything() { return 42; }
"""


from codemanip import code_utils


def postprocess_stub(code: str) -> str:
    return (
        code_utils.unindent_code(
            """
        # Copyright(c) 2023 - Pascal Thomet
        #    Yes, I claim the copyright on this magnificent function.
        #    ...At least, I tried...
        """
        )
        + code
    )


def postprocess_pydef(code: str) -> str:
    return (
        code_utils.unindent_code(
            """
        // Copyright(c) 2023 - Pascal Thomet
        //    Yes, I claim the copyright on this magnificent function.
        //    ...At least, I tried...
        """
        )
        + code
    )


options = litgen.LitgenOptions()
options.postprocess_stub_function = postprocess_stub
options.postprocess_pydef_function = postprocess_pydef
litgen_demo.demo(options, cpp_code, show_pydef=True)

Original C++ decls

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int AnswerToTheUltimateQuestionOfLife_TheUniverse_AndEverything() { return 42; }

Corresponding python decls (stub)

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# Copyright(c) 2023 - Pascal Thomet
#    Yes, I claim the copyright on this magnificent function.
#    ...At least, I tried...

def answer_to_the_ultimate_question_of_life_the_universe_and_everything() -> int:
    pass

pybind11 C++ binding code

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// Copyright(c) 2023 - Pascal Thomet
//    Yes, I claim the copyright on this magnificent function.
//    ...At least, I tried...
m.def("answer_to_the_ultimate_question_of_life_the_universe_and_everything",
    AnswerToTheUltimateQuestionOfLife_TheUniverse_AndEverything);

nanobind C++ binding code

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// Copyright(c) 2023 - Pascal Thomet
//    Yes, I claim the copyright on this magnificent function.
//    ...At least, I tried...
m.def("answer_to_the_ultimate_question_of_life_the_universe_and_everything",
    AnswerToTheUltimateQuestionOfLife_TheUniverse_AndEverything);