How can the libclang python bindings be used to analyze C code, make modifications to individual nodes, and generate a new version of the C code that can be compiled again?

edit

Install libclang and the corresponding Python bindings. This can be done using pip:

pip install clang

Use the Index class to create an index object:

from clang.cindex import Index
index = Index.create()

Use the index object to create a TranslationUnit object, which represents the parsed C code:

translation_unit = index.parse(path_to_c_file)

Traverse the AST (abstract syntax tree) of the code using the Cursor class:

def traverse(cursor):
    for child in cursor.get_children():
        # process the node
        traverse(child)

traverse(translation_unit.cursor)

Use the Cursor class to modify nodes in the AST:

def modify_node(cursor):
    if cursor.kind == clang.cindex.CursorKind.FUNCTION_DECL:
        cursor.name = "new_function_name"

traverse(translation_unit.cursor)

Use the SourceRange class to get the source code of nodes in the AST:

def get_code(cursor):
    location = cursor.extent.start
    end_location = cursor.extent.end
    with open(path_to_c_file, 'r') as f:
        f.seek(location.offset)
        code = f.read(end_location.offset - location.offset)
    return code

function_code = get_code(function_cursor)

Generate a new version of the C code using the modified AST:

def generate_new_code(cursor):
    output = []
    start_location = cursor.extent.start
    end_location = cursor.extent.end
    with open(path_to_c_file, 'r') as f:
        output.append(f.read(start_location.offset))
        # generate code for modified node
        if cursor.kind == clang.cindex.CursorKind.FUNCTION_DECL:
            output.append(generate_new_function_code(cursor))
        else:
            output.append(f.read(end_location.offset - start_location.offset))
    output.append(f.read())
    return ''.join(output)

new_code = generate_new_code(translation_unit.cursor)

Save the new code to a file and compile it:

with open('new_code.c', 'w') as f:
    f.write(new_code)