Preprocessor and macros - litgen, the Literate Generator

Export macro values into the python module¶

Some #define macros can be exported:

Simple preprocessor defines can be exported as global variables, e.g.:

    #define MYLIB_VALUE 1
    #define MYLIB_FLOAT 1.5
    #define MYLIB_STRING "abc"
    #define MYLIB_HEX_VALUE 0x00010009

This is limited to simple defines.

You can also apply a simple renaming to the macro value: see example below.

cpp_code = """
    #define MYLIB_VALUE 1
    #define MYLIB_FLOAT 1.5
    #define MYLIB_STRING "abc"
    #define MYLIB_HEX_VALUE 0x00010009
"""

import litgen
from litgen.demo import litgen_demo

options = litgen.LitgenOptions()
options.macro_define_include_by_name__regex = "^MYLIB_"
# Suppress the "MYLIB_" prefix:
options.macro_name_replacements.add_first_replacement(r"^MYLIB_([A-Z_]*)", r"\1")
litgen_demo.demo(options, cpp_code, show_pydef=True)

Set numeric macro values¶

Sometimes, it is necessary to tell litgen the value of certain numeric macros. In the example below, the member values can be exposed as a numpy array, but litgen needs to know it size.

We set it via the option:

    options.srcmlcpp_options.named_number_macros["MY_COUNT"] = 256

cpp_code = """
#define MY_COUNT 256

struct Foo
{
    int values[MY_COUNT];
};
"""

options = litgen.LitgenOptions()
options.srcmlcpp_options.named_number_macros["MY_COUNT"] = 256

litgen_demo.demo(options, cpp_code)