obast.py

obast.py

import ast

ast = ast.parse('a = (1 + 2)\n', filename='<string>', mode='single')
statement, *_ = ast.body

def walk(node, field='', depth=0):
    indent = depth * '    '
    name = node.__class__.__name__

    if isinstance(node, list):
        for n in node:
            walk(n, field, depth)
        return

    if hasattr(node, '_fields'):
        print(f'{indent}{field}:{name}')
        for field in node._fields:
            child = getattr(node, field)
            walk(child, field, depth + 1)
        return

    print(f'{indent}{field}:{node}')

walk(statement, 'Statement')

output.txt

Statement:Assign
    targets:Name
        id:a
        ctx:Store
    value:BinOp
        left:Num
            n:1
        op:Add
        right:Num
            n:2