Refactor parsing of function in CodeInput using ast

[agoscinski]

The problem with inspect is that ignores the actual formatting provided by the user and that it sometimes stores directly the related objects (e.g. type annotation x: int stores the type int instead of the string int which makes it hard to pass as string later on). With ast this should be resolved. See example

def mock_function_1(x: int, y: int):
    """
    This is an example function.
    It adds two numbers.
    """
    if x > 0:
        return x + y
    else:
        return y

import ast, inspect
module = ast.parse(inspect.getsource(mock_function_1))
ast.dump(module)

#Out: "Module(body=[FunctionDef(name='mock_function_1', args=arguments(posonlyargs=[], args=[arg(arg='x', annotation=Name(id='int', ctx=Load())), arg(arg='y', annotation=Name(id='int', ctx=Load()))], kwonlyargs=[], kw_defaults=[], defaults=[]), body=[Expr(value=Constant(value='\\n    This is an example function.\\n    It adds two numbers.\\n    ')), If(test=Compare(left=Name(id='x', ctx=Load()), ops=[Gt()], comparators=[Constant(value=0)]), body=[Return(value=BinOp(left=Name(id='x', ctx=Load()), op=Add(), right=Name(id='y', ctx=Load())))], orelse=[Return(value=Name(id='y', ctx=Load()))])], decorator_list=[])], type_ignores=[])"

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📚 Documentation preview 📚: https://scicode-widgets--86.org.readthedocs.build/en/86/

[agoscinski]

Sadly the ast module by design ignores comment which makes it not applicable for this approach

[agoscinski]

For reference this is how get_function_body could have been changed, but we cannot take this approach since it removes comments that are essential for the function body

    @staticmethod
    def get_function_body(function: types.FunctionType) -> str:
        function_source, function_definition = CodeInput._get_function_source_and_def(
            function
        )

        ast_functon_body = function_definition.body[-1]

        source_function_body = ast.get_source_segment(
            function_source, ast_functon_body, padded=True
        )
        breakpoint()
        if source_function_body is None:
            raise ValueError("Could not extract function body.")
        source_function_body = textwrap.dedent(source_function_body)
        return source_function_body

[agoscinski]

We still fix the formatting for parsing the parameters but it this avoids including regex expressions that are harder to maintain.