Class ASTGrammarPrinter

Tools/peg_generator/pegen/grammar_visualizer.py:15–47

class ASTGrammarPrinter:
    def children(self, node: Rule) -> Iterator[Any]:
        for value in node:
            if isinstance(value, list):
                yield from value
            else:
                yield value

    def name(self, node: Rule) -> str:
        if not list(self.children(node)):
            return repr(node)
        return node.__class__.__name__

    def print_grammar_ast(self, grammar: Grammar, printer: Callable[..., None] = print) -> None:
        for rule in grammar.rules.values():
            printer(self.print_nodes_recursively(rule))

    def print_nodes_recursively(self, node: Rule, prefix: str = "", istail: bool = True) -> str:
        children = list(self.children(node))
        value = self.name(node)

        line = prefix + ("└──" if istail else "├──") + value + "\n"
        sufix = "   " if istail else "│  "

        if not children:
            return line

        *children, last = children
        for child in children:
            line += self.print_nodes_recursively(child, prefix + sufix, False)
        line += self.print_nodes_recursively(last, prefix + sufix, True)

        return line


def main() -> None: