src/black/debug.py

   1 from dataclasses import dataclass
   2 from typing import Iterator, TypeVar, Union
   3
   4 from black.nodes import Visitor
   5 from black.output import out
   6 from black.parsing import lib2to3_parse
   7 from blib2to3.pgen2 import token
   8 from blib2to3.pytree import Leaf, Node, type_repr
   9
  10 LN = Union[Leaf, Node]
  11 T = TypeVar("T")
  12
  13
  14 @dataclass
  15 class DebugVisitor(Visitor[T]):
  16     tree_depth: int = 0
  17
  18     def visit_default(self, node: LN) -> Iterator[T]:
  19         indent = " " * (2 * self.tree_depth)
  20         if isinstance(node, Node):
  21             _type = type_repr(node.type)
  22             out(f"{indent}{_type}", fg="yellow")
  23             self.tree_depth += 1
  24             for child in node.children:
  25                 yield from self.visit(child)
  26
  27             self.tree_depth -= 1
  28             out(f"{indent}/{_type}", fg="yellow", bold=False)
  29         else:
  30             _type = token.tok_name.get(node.type, str(node.type))
  31             out(f"{indent}{_type}", fg="blue", nl=False)
  32             if node.prefix:
  33                 # We don't have to handle prefixes for `Node` objects since
  34                 # that delegates to the first child anyway.
  35                 out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
  36             out(f" {node.value!r}", fg="blue", bold=False)
  37
  38     @classmethod
  39     def show(cls, code: Union[str, Leaf, Node]) -> None:
  40         """Pretty-print the lib2to3 AST of a given string of `code`.
  41
  42         Convenience method for debugging.
  43         """
  44         v: DebugVisitor[None] = DebugVisitor()
  45         if isinstance(code, str):
  46             code = lib2to3_parse(code)
  47         list(v.visit(code))