Merged revisions 61596-61597 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
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r61596 | martin.v.loewis | 2008-03-18 23:43:46 -0500 (Di, 18 Mär 2008) | 2 lines
Import lib2to3.
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r61597 | martin.v.loewis | 2008-03-18 23:58:04 -0500 (Di, 18 Mär 2008) | 3 lines
Initialized merge tracking via "svnmerge" with revisions "1-61595" from
svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3
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diff --git a/Lib/lib2to3/pgen2/literals.py b/Lib/lib2to3/pgen2/literals.py
new file mode 100644
index 0000000..0b3948a
--- /dev/null
+++ b/Lib/lib2to3/pgen2/literals.py
@@ -0,0 +1,60 @@
+# 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 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)
+ else:
+ try:
+ i = int(tail, 8)
+ except ValueError:
+ raise ValueError("invalid octal string escape ('\\%s')" % tail)
+ 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()