cpython/Tools/peg_generator/pegen/tokenizer.py

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import token
import tokenize
from typing import List, Iterator
Mark = int # NewType('Mark', int)
exact_token_types = token.EXACT_TOKEN_TYPES # type: ignore
def shorttok(tok: tokenize.TokenInfo) -> str:
return "%-25.25s" % f"{tok.start[0]}.{tok.start[1]}: {token.tok_name[tok.type]}:{tok.string!r}"
class Tokenizer:
"""Caching wrapper for the tokenize module.
This is pretty tied to Python's syntax.
"""
_tokens: List[tokenize.TokenInfo]
def __init__(self, tokengen: Iterator[tokenize.TokenInfo], *, verbose: bool = False):
self._tokengen = tokengen
self._tokens = []
self._index = 0
self._verbose = verbose
if verbose:
self.report(False, False)
def getnext(self) -> tokenize.TokenInfo:
"""Return the next token and updates the index."""
cached = True
while self._index == len(self._tokens):
tok = next(self._tokengen)
if tok.type in (tokenize.NL, tokenize.COMMENT):
continue
if tok.type == token.ERRORTOKEN and tok.string.isspace():
continue
self._tokens.append(tok)
cached = False
tok = self._tokens[self._index]
self._index += 1
if self._verbose:
self.report(cached, False)
return tok
def peek(self) -> tokenize.TokenInfo:
"""Return the next token *without* updating the index."""
while self._index == len(self._tokens):
tok = next(self._tokengen)
if tok.type in (tokenize.NL, tokenize.COMMENT):
continue
if tok.type == token.ERRORTOKEN and tok.string.isspace():
continue
self._tokens.append(tok)
return self._tokens[self._index]
def diagnose(self) -> tokenize.TokenInfo:
if not self._tokens:
self.getnext()
return self._tokens[-1]
def mark(self) -> Mark:
return self._index
def reset(self, index: Mark) -> None:
if index == self._index:
return
assert 0 <= index <= len(self._tokens), (index, len(self._tokens))
old_index = self._index
self._index = index
if self._verbose:
self.report(True, index < old_index)
def report(self, cached: bool, back: bool) -> None:
if back:
fill = "-" * self._index + "-"
elif cached:
fill = "-" * self._index + ">"
else:
fill = "-" * self._index + "*"
if self._index == 0:
print(f"{fill} (Bof)")
else:
tok = self._tokens[self._index - 1]
print(f"{fill} {shorttok(tok)}")