--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flagReader.py	Wed Mar 05 12:16:19 2008 -0500
@@ -0,0 +1,88 @@
+"""Defines and parses UNIX-style flags to modify command arguments.
+
+print flagReader.FlagSet.parse.__doc__ for usage examples.
+"""
+
+import re
+
+class Flag(object):
+    def __init__(self, name, abbrev=None, nargs=0):
+        """Flag(name, abbrev=None, nargs=0) : Defines a flag.
+        
+        name: the full name of the flag (double-dash form)
+        abbrev: the single-letter abbreviated form of the flag; defaults to 
+        nargs: number of arguments expected after the flag"""
+        
+        self.name = name
+        self.abbrev = abbrev or name[0]
+        self.fullabbrev = '-%s' % (self.abbrev)
+        self.fullname = '--%s' % (name)
+        self.nargs = nargs
+
+class FlagSet(object):
+    def __init__(self, flags):
+        if not issubclass(type(flags), list):
+            raise TypeError, 'Argument must be a list'
+        self.flags = flags
+        self.lookup = {}
+        for flag in self.flags:
+            self.lookup[flag.abbrev] = flag
+            self.lookup[flag.fullabbrev] = flag
+            self.lookup[flag.fullname] = flag
+        self.abbrevPattern = re.compile('^-([%s]+)$' % (''.join(f.abbrev for f in flags)))
+    def parse(self, arg):
+        """
+        Finds flags; returns {flag: (values, if any)} and the remaining argument.
+        
+        >>> f = FlagSet([Flag('foo'), Flag('bar'), Flag('gimmea', nargs=1)])
+        >>> f.parse('-fb')
+        ({'foo': [], 'bar': []}, '')
+        >>> f.parse('no flags')
+        ({}, 'no flags')
+        >>> f.parse('-f blah')
+        ({'foo': []}, 'blah')
+        >>> f.parse('--bar')
+        ({'bar': []}, '')
+        >>> f.parse('--bar -f')
+        ({'foo': [], 'bar': []}, '')
+        >>> f.parse('--notaflag')
+        ({}, '--notaflag')
+        >>> f.parse('')
+        ({}, '')
+        >>> f.parse('--gimmea bee -f and then some other     stuff')
+        ({'gimmea': ['bee'], 'foo': []}, 'and then some other stuff')
+        >>> f.parse('hidden -bar')
+        ({}, 'hidden -bar')
+        >>> f.parse('-g myarg -b')
+        ({'gimmea': ['myarg'], 'bar': []}, '')
+        """
+        result = {}
+        words = arg.split()
+        while words:
+            word = words[0]
+            flag = self.lookup.get(word)
+            if flag:
+                result[flag.name] = []
+                words.pop(0)
+                for arg in range(flag.nargs):
+                    try:
+                        result[flag.name].append(words.pop(0))
+                    except IndexError: # there aren't as many args as we expect
+                        raise IndexError, '%s expects %d arguments' % (word, flag.nargs)
+                continue  # on to next word
+            smashedAbbrevs = self.abbrevPattern.search(word)
+            if smashedAbbrevs:
+                for abbrev in smashedAbbrevs.group(1):
+                    result[self.lookup[abbrev].name] = []
+                words.pop(0)
+                continue # on to next word
+            #if you get to here, word[0] does not denote options
+            break
+        return result, ' '.join(words)
+
+def _test():
+    import doctest
+    doctest.testmod()
+    
+if __name__ == '__main__':
+    _test()
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