00.output

python 00*.py
 @ file_input ...
   @ funcdef ...
     @ NAME Leaf(1, 'def')
     @ NAME Leaf(1, 'f')
     @ parameters ...
       @ LPAR ...
       @ tname ...
         @ NAME Leaf(1, 'x')
         @ COLON ...
         @ NAME Leaf(1, 'int')
       @ RPAR ...
     @ RARROW ...
     @ NAME Leaf(1, 'int')
     @ COLON ...
     @ suite ...
       @ NEWLINE ...
       @ INDENT ...
       @ if_stmt ...
         @ NAME Leaf(1, 'if')
         @ comparison ...
           @ NAME Leaf(1, 'x')
           @ EQEQUAL ...
           @ NUMBER ...
         @ COLON ...
         @ suite ...
           @ NEWLINE ...
           @ INDENT ...
           @ simple_stmt ...
             @ return_stmt ...
               @ NAME Leaf(1, 'return')
               @ NUMBER ...
             @ NEWLINE ...
           @ DEDENT ...
         @ NAME Leaf(1, 'else')
         @ COLON ...
         @ suite ...
           @ NEWLINE ...
           @ INDENT ...
           @ simple_stmt ...
             @ return_stmt ...
               @ NAME Leaf(1, 'return')
               @ term ...
                 @ NAME Leaf(1, 'x')
                 @ STAR ...
                 @ power ...
                   @ NAME Leaf(1, 'f')
                   @ trailer ...
                     @ LPAR ...
                     @ arith_expr ...
                       @ NAME Leaf(1, 'x')
                       @ MINUS ...
                       @ NUMBER ...
                     @ RPAR ...
             @ NEWLINE ...
           @ DEDENT ...
       @ DEDENT ...
   @ ENDMARKER ...

00parse_ast.py

from parse import parse_string, PyTreeVisitor

code = """\
# toplevel comments

def  f(x:int) -> int:
    # condition, (inner comments)
    if x == 0:
        return 1
    else:
        return x * f(x - 1)
"""

t = parse_string(code)
visitor = PyTreeVisitor()
visitor.visit(t)

a.diff

diff --git a/daily/20190706/example_debug_recursive/parse.py b/daily/20190706/example_debug_recursive/parse.py
index d80d55f..82ad566 100644
--- a/daily/20190706/example_debug_recursive/parse.py
+++ b/daily/20190706/example_debug_recursive/parse.py
@@ -29,6 +29,14 @@ def node_value(node):
 
 class PyTreeVisitor:
     def visit(self, node):
+        import traceback
+
+        print(
+            " " * (len(traceback.extract_stack()) - 2),
+            "@",
+            node_name(node),
+            node_value(node),
+        )
         method = "visit_{0}".format(node_name(node))
         if hasattr(self, method):
             # Found a specific visitor for this node

Makefile

00:
	python 00*.py

parse.py

from lib2to3 import pytree
from lib2to3 import pygram
from lib2to3.pgen2 import driver
from lib2to3.pgen2 import token

default_driver = driver.Driver(
    pygram.python_grammar_no_print_statement, convert=pytree.convert
)


def parse_string(code, parser_driver=default_driver, *, debug=True):
    return parser_driver.parse_string(code, debug=debug)


def node_name(node):
    # Nodes with values < 256 are tokens. Values >= 256 are grammar symbols.
    if node.type < 256:
        return token.tok_name[node.type]
    else:
        return pygram.python_grammar.number2symbol[node.type]


def node_value(node):
    if node_name(node) == "NAME":
        return repr(node)
    else:
        return "..."


class PyTreeVisitor:
    def visit(self, node):
        import traceback

        print(
            " " * (len(traceback.extract_stack()) - 2),
            "@",
            node_name(node),
            node_value(node),
        )
        method = "visit_{0}".format(node_name(node))
        if hasattr(self, method):
            # Found a specific visitor for this node
            if getattr(self, method)(node):
                return

        elif hasattr(node, "value"):  # Leaf
            self.default_leaf_visit(node)
        else:
            self.default_node_visit(node)

    def default_node_visit(self, node):
        for child in node.children:
            self.visit(child)

    def default_leaf_visit(self, leaf):
        pass