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| 1 """A copy of the string Template class from python 2.4, included | |
| 2 for compatibility with python 2.3. | |
| 3 """ | |
| 4 | |
| 5 import re as _re | |
| 6 | |
| 7 class _multimap: | |
| 8 """Helper class for combining multiple mappings. | |
| 9 | |
| 10 Used by .{safe_,}substitute() to combine the mapping and keyword | |
| 11 arguments. | |
| 12 """ | |
| 13 def __init__(self, primary, secondary): | |
| 14 self._primary = primary | |
| 15 self._secondary = secondary | |
| 16 | |
| 17 def __getitem__(self, key): | |
| 18 try: | |
| 19 return self._primary[key] | |
| 20 except KeyError: | |
| 21 return self._secondary[key] | |
| 22 | |
| 23 | |
| 24 class _TemplateMetaclass(type): | |
| 25 pattern = r""" | |
| 26 %(delim)s(?: | |
| 27 (?P<escaped>%(delim)s) | # Escape sequence of two delimiters | |
| 28 (?P<named>%(id)s) | # delimiter and a Python identifier | |
| 29 {(?P<braced>%(id)s)} | # delimiter and a braced identifier | |
| 30 (?P<invalid>) # Other ill-formed delimiter exprs | |
| 31 ) | |
| 32 """ | |
| 33 | |
| 34 def __init__(cls, name, bases, dct): | |
| 35 super(_TemplateMetaclass, cls).__init__(name, bases, dct) | |
| 36 if 'pattern' in dct: | |
| 37 pattern = cls.pattern | |
| 38 else: | |
| 39 pattern = _TemplateMetaclass.pattern % { | |
| 40 'delim' : _re.escape(cls.delimiter), | |
| 41 'id' : cls.idpattern, | |
| 42 } | |
| 43 cls.pattern = _re.compile(pattern, _re.IGNORECASE | _re.VERBOSE) | |
| 44 | |
| 45 | |
| 46 class Template: | |
| 47 """A string class for supporting $-substitutions.""" | |
| 48 __metaclass__ = _TemplateMetaclass | |
| 49 | |
| 50 delimiter = '$' | |
| 51 idpattern = r'[_a-z][_a-z0-9]*' | |
| 52 | |
| 53 def __init__(self, template): | |
| 54 self.template = template | |
| 55 | |
| 56 # Search for $$, $identifier, ${identifier}, and any bare $'s | |
| 57 | |
| 58 def _invalid(self, mo): | |
| 59 i = mo.start('invalid') | |
| 60 lines = self.template[:i].splitlines(True) | |
| 61 if not lines: | |
| 62 colno = 1 | |
| 63 lineno = 1 | |
| 64 else: | |
| 65 colno = i - len(''.join(lines[:-1])) | |
| 66 lineno = len(lines) | |
| 67 raise ValueError('Invalid placeholder in string: line %d, col %d' % | |
| 68 (lineno, colno)) | |
| 69 | |
| 70 def substitute(self, *args, **kws): | |
| 71 if len(args) > 1: | |
| 72 raise TypeError('Too many positional arguments') | |
| 73 if not args: | |
| 74 mapping = kws | |
| 75 elif kws: | |
| 76 mapping = _multimap(kws, args[0]) | |
| 77 else: | |
| 78 mapping = args[0] | |
| 79 # Helper function for .sub() | |
| 80 def convert(mo): | |
| 81 # Check the most common path first. | |
| 82 named = mo.group('named') or mo.group('braced') | |
| 83 if named is not None: | |
| 84 val = mapping[named] | |
| 85 # We use this idiom instead of str() because the latter will | |
| 86 # fail if val is a Unicode containing non-ASCII characters. | |
| 87 return '%s' % val | |
| 88 if mo.group('escaped') is not None: | |
| 89 return self.delimiter | |
| 90 if mo.group('invalid') is not None: | |
| 91 self._invalid(mo) | |
| 92 raise ValueError('Unrecognized named group in pattern', | |
| 93 self.pattern) | |
| 94 return self.pattern.sub(convert, self.template) | |
| 95 | |
| 96 def safe_substitute(self, *args, **kws): | |
| 97 if len(args) > 1: | |
| 98 raise TypeError('Too many positional arguments') | |
| 99 if not args: | |
| 100 mapping = kws | |
| 101 elif kws: | |
| 102 mapping = _multimap(kws, args[0]) | |
| 103 else: | |
| 104 mapping = args[0] | |
| 105 # Helper function for .sub() | |
| 106 def convert(mo): | |
| 107 named = mo.group('named') | |
| 108 if named is not None: | |
| 109 try: | |
| 110 # We use this idiom instead of str() because the latter | |
| 111 # will fail if val is a Unicode containing non-ASCII | |
| 112 return '%s' % mapping[named] | |
| 113 except KeyError: | |
| 114 return self.delimiter + named | |
| 115 braced = mo.group('braced') | |
| 116 if braced is not None: | |
| 117 try: | |
| 118 return '%s' % mapping[braced] | |
| 119 except KeyError: | |
| 120 return self.delimiter + '{' + braced + '}' | |
| 121 if mo.group('escaped') is not None: | |
| 122 return self.delimiter | |
| 123 if mo.group('invalid') is not None: | |
| 124 return self.delimiter | |
| 125 raise ValueError('Unrecognized named group in pattern', | |
| 126 self.pattern) | |
| 127 return self.pattern.sub(convert, self.template) | |
| 128 | |
| 129 | |
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