# Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

"""
Python parse tree definitions.

This is a very concrete parse tree; we need to keep every token and
even the comments and whitespace between tokens.

There's also a pattern matching implementation here.
"""

__author__ = "Guido van Rossum <guido@python.org>"

import os

from . import pgen2

# The grammar file
_GRAMMAR_FILE = os.path.join(os.path.dirname(__file__), "grammar3.4.txt")


class Symbols(object):
    def __init__(self, grammar):
        """Initializer.

        Creates an attribute for each grammar symbol (nonterminal),
        whose value is the symbol's type (an int >= 256).
        """
        for name, symbol in grammar.symbol2number.items():
            setattr(self, name, symbol)


python_grammar = pgen2.load_grammar(_GRAMMAR_FILE)
python_symbols = Symbols(python_grammar)
python_grammar_no_print_statement = python_grammar.copy()
_type_reprs = {}

try:
    del python_grammar_no_print_statement.keywords["print"]
except KeyError:
    pass  # Doesn't exist in the Python 3 grammar.


def type_repr(type_num):
    global _type_reprs
    if not _type_reprs:
        # printing tokens is possible but not as useful
        # from .pgen2 import token // token.__dict__.items():
        for name, val in python_symbols.__dict__.items():
            if type(val) == int:
                _type_reprs[val] = name
    return _type_reprs.setdefault(type_num, type_num)