djavu-asus/emacs/elpy/rpc-venv/lib/python3.11/site-packages/blib2to3/pgen2/literals.py

   1 # Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
   2 # Licensed to PSF under a Contributor Agreement.
   3
   4 """Safely evaluate Python string literals without using eval()."""
   5
   6 import re
   7 from typing import Dict, Match
   8
   9 simple_escapes: Dict[str, str] = {
  10     "a": "\a",
  11     "b": "\b",
  12     "f": "\f",
  13     "n": "\n",
  14     "r": "\r",
  15     "t": "\t",
  16     "v": "\v",
  17     "'": "'",
  18     '"': '"',
  19     "\\": "\\",
  20 }
  21
  22
  23 def escape(m: Match[str]) -> str:
  24     all, tail = m.group(0, 1)
  25     assert all.startswith("\\")
  26     esc = simple_escapes.get(tail)
  27     if esc is not None:
  28         return esc
  29     if tail.startswith("x"):
  30         hexes = tail[1:]
  31         if len(hexes) < 2:
  32             raise ValueError("invalid hex string escape ('\\%s')" % tail)
  33         try:
  34             i = int(hexes, 16)
  35         except ValueError:
  36             raise ValueError("invalid hex string escape ('\\%s')" % tail) from None
  37     else:
  38         try:
  39             i = int(tail, 8)
  40         except ValueError:
  41             raise ValueError("invalid octal string escape ('\\%s')" % tail) from None
  42     return chr(i)
  43
  44
  45 def evalString(s: str) -> str:
  46     assert s.startswith("'") or s.startswith('"'), repr(s[:1])
  47     q = s[0]
  48     if s[:3] == q * 3:
  49         q = q * 3
  50     assert s.endswith(q), repr(s[-len(q) :])
  51     assert len(s) >= 2 * len(q)
  52     s = s[len(q) : -len(q)]
  53     return re.sub(r"\\(\'|\"|\\|[abfnrtv]|x.{0,2}|[0-7]{1,3})", escape, s)
  54
  55
  56 def test() -> None:
  57     for i in range(256):
  58         c = chr(i)
  59         s = repr(c)
  60         e = evalString(s)
  61         if e != c:
  62             print(i, c, s, e)
  63
  64
  65 if __name__ == "__main__":
  66     test()