black/blib2to3/pgen2/literals.py
Michael J. Sullivan 0ff718e1e2 Blacken .py files in blib2to3 (#1011)
* Blacken .py files in blib2to3

This is in preparation for adding type annotations to blib2to3 in
order to compiling it with mypyc (#1009, which I can rebase on top of
this).

To enforce that it stays blackened, I just cargo-culted the existing
test code used for validating formatting. It feels pretty clunky now,
though, so I can abstract the common logic out into a helper if that
seems better. (But error messages might be less clear then?)

* Tidy up the tests
2019-10-20 15:55:31 +02:00

66 lines
1.5 KiB
Python

# Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Safely evaluate Python string literals without using eval()."""
import regex as re
simple_escapes = {
"a": "\a",
"b": "\b",
"f": "\f",
"n": "\n",
"r": "\r",
"t": "\t",
"v": "\v",
"'": "'",
'"': '"',
"\\": "\\",
}
def escape(m):
all, tail = m.group(0, 1)
assert all.startswith("\\")
esc = simple_escapes.get(tail)
if esc is not None:
return esc
if tail.startswith("x"):
hexes = tail[1:]
if len(hexes) < 2:
raise ValueError("invalid hex string escape ('\\%s')" % tail)
try:
i = int(hexes, 16)
except ValueError:
raise ValueError("invalid hex string escape ('\\%s')" % tail) from None
else:
try:
i = int(tail, 8)
except ValueError:
raise ValueError("invalid octal string escape ('\\%s')" % tail) from None
return chr(i)
def evalString(s):
assert s.startswith("'") or s.startswith('"'), repr(s[:1])
q = s[0]
if s[:3] == q * 3:
q = q * 3
assert s.endswith(q), repr(s[-len(q) :])
assert len(s) >= 2 * len(q)
s = s[len(q) : -len(q)]
return re.sub(r"\\(\'|\"|\\|[abfnrtv]|x.{0,2}|[0-7]{1,3})", escape, s)
def test():
for i in range(256):
c = chr(i)
s = repr(c)
e = evalString(s)
if e != c:
print(i, c, s, e)
if __name__ == "__main__":
test()