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At the cost of a modest (but useful in its own right) change in the semantics

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of the Template.delimiter attribute, we make use of the delimiter in the
escaped group, and in the safe_substitute() method more robust.

Now, .delimiter should be the unescaped delimiter literal, e.g. '$' or '&', or
whatever.  The _TemplateMetaclass will re.escape() this value when it builds
the pattern.
This commit is contained in:
Barry Warsaw 2004-09-18 00:06:34 +00:00
parent 2e6fb4634c
commit 17cb60083c
1 changed files with 6 additions and 8 deletions
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14
Lib/string.py
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@ -113,7 +113,7 @@ class _TemplateMetaclass(type):
pattern = cls.pattern pattern = cls.pattern
else: else:
pattern = _TemplateMetaclass.pattern % { pattern = _TemplateMetaclass.pattern % {
'delim' : cls.delimiter, 'delim' : _re.escape(cls.delimiter),
'id' : cls.idpattern, 'id' : cls.idpattern,
} }
cls.pattern = _re.compile(pattern, _re.IGNORECASE | _re.VERBOSE) cls.pattern = _re.compile(pattern, _re.IGNORECASE | _re.VERBOSE)
@ -123,7 +123,7 @@ class Template:
"""A string class for supporting $-substitutions.""" """A string class for supporting $-substitutions."""
__metaclass__ = _TemplateMetaclass __metaclass__ = _TemplateMetaclass
delimiter = r'\$' delimiter = '$'
idpattern = r'[_a-z][_a-z0-9]*' idpattern = r'[_a-z][_a-z0-9]*'
def __init__(self, template): def __init__(self, template):
@ -152,7 +152,6 @@ class Template:
mapping = _multimap(kws, args[0]) mapping = _multimap(kws, args[0])
else: else:
mapping = args[0] mapping = args[0]
delimiter = self.delimiter[-1]
# Helper function for .sub() # Helper function for .sub()
def convert(mo): def convert(mo):
# Check the most common path first. # Check the most common path first.
@ -163,7 +162,7 @@ class Template:
# fail if val is a Unicode containing non-ASCII characters. # fail if val is a Unicode containing non-ASCII characters.
return '%s' % val return '%s' % val
if mo.group('escaped') is not None: if mo.group('escaped') is not None:
return delimiter return self.delimiter
if mo.group('invalid') is not None: if mo.group('invalid') is not None:
self._invalid(mo) self._invalid(mo)
raise ValueError('Unrecognized named group in pattern', pattern) raise ValueError('Unrecognized named group in pattern', pattern)
@ -178,7 +177,6 @@ class Template:
mapping = _multimap(kws, args[0]) mapping = _multimap(kws, args[0])
else: else:
mapping = args[0] mapping = args[0]
delimiter = self.delimiter[-1]
# Helper function for .sub() # Helper function for .sub()
def convert(mo): def convert(mo):
named = mo.group('named') named = mo.group('named')
@ -188,15 +186,15 @@ class Template:
# will fail if val is a Unicode containing non-ASCII # will fail if val is a Unicode containing non-ASCII
return '%s' % mapping[named] return '%s' % mapping[named]
except KeyError: except KeyError:
return delimiter + named return self.delimiter + named
braced = mo.group('braced') braced = mo.group('braced')
if braced is not None: if braced is not None:
try: try:
return '%s' % mapping[braced] return '%s' % mapping[braced]
except KeyError: except KeyError:
return delimiter + '{' + braced + '}' return self.delimiter + '{' + braced + '}'
if mo.group('escaped') is not None: if mo.group('escaped') is not None:
return delimiter return self.delimiter
if mo.group('invalid') is not None: if mo.group('invalid') is not None:
self._invalid(mo) self._invalid(mo)
raise ValueError('Unrecognized named group in pattern', pattern) raise ValueError('Unrecognized named group in pattern', pattern)