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c:\python24\lib \ shlex.py



0001 # -*- coding: iso-8859-1 -*-
0002 """A lexical analyzer class for simple shell-like syntaxes."""
0003 
0004 # Module and documentation by Eric S. Raymond, 21 Dec 1998
0005 # Input stacking and error message cleanup added by ESR, March 2000
0006 # push_source() and pop_source() made explicit by ESR, January 2001.
0007 # Posix compliance, split(), string arguments, and
0008 # iterator interface by Gustavo Niemeyer, April 2003.
0009 
0010 import os.path
0011 import sys
0012 from collections import deque
0013 
0014 try:
0015     from cStringIO import StringIO
0016 except ImportError:
0017     from StringIO import StringIO
0018 
0019 __all__ = ["shlex", "split"]
0020 
0021 class shlex:
0022     "A lexical analyzer class for simple shell-like syntaxes."
0023     def __init__(self, instream=None, infile=None, posix=False):
0024         if isinstance(instream, basestring):
0025             instream = StringIO(instream)
0026         if instream is not None:
0027             self.instream = instream
0028             self.infile = infile
0029         else:
0030             self.instream = sys.stdin
0031             self.infile = None
0032         self.posix = posix
0033         if posix:
0034             self.eof = None
0035         else:
0036             self.eof = ''
0037         self.commenters = '#'
0038         self.wordchars = ('abcdfeghijklmnopqrstuvwxyz'
0039                           'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_')
0040         if self.posix:
0041             self.wordchars += (''
0042                                '')
0043         self.whitespace = ' \t\r\n'
0044         self.whitespace_split = False
0045         self.quotes = '\'"'
0046         self.escape = '\\'
0047         self.escapedquotes = '"'
0048         self.state = ' '
0049         self.pushback = deque()
0050         self.lineno = 1
0051         self.debug = 0
0052         self.token = ''
0053         self.filestack = deque()
0054         self.source = None
0055         if self.debug:
0056             print 'shlex: reading from %s, line %d' \
0057                   % (self.instream, self.lineno)
0058 
0059     def push_token(self, tok):
0060         "Push a token onto the stack popped by the get_token method"
0061         if self.debug >= 1:
0062             print "shlex: pushing token " + repr(tok)
0063         self.pushback.appendleft(tok)
0064 
0065     def push_source(self, newstream, newfile=None):
0066         "Push an input source onto the lexer's input source stack."
0067         if isinstance(newstream, basestring):
0068             newstream = StringIO(newstream)
0069         self.filestack.appendleft((self.infile, self.instream, self.lineno))
0070         self.infile = newfile
0071         self.instream = newstream
0072         self.lineno = 1
0073         if self.debug:
0074             if newfile is not None:
0075                 print 'shlex: pushing to file %s' % (self.infile,)
0076             else:
0077                 print 'shlex: pushing to stream %s' % (self.instream,)
0078 
0079     def pop_source(self):
0080         "Pop the input source stack."
0081         self.instream.close()
0082         (self.infile, self.instream, self.lineno) = self.filestack.popleft()
0083         if self.debug:
0084             print 'shlex: popping to %s, line %d' \
0085                   % (self.instream, self.lineno)
0086         self.state = ' '
0087 
0088     def get_token(self):
0089         "Get a token from the input stream (or from stack if it's nonempty)"
0090         if self.pushback:
0091             tok = self.pushback.popleft()
0092             if self.debug >= 1:
0093                 print "shlex: popping token " + repr(tok)
0094             return tok
0095         # No pushback.  Get a token.
0096         raw = self.read_token()
0097         # Handle inclusions
0098         if self.source is not None:
0099             while raw == self.source:
0100                 spec = self.sourcehook(self.read_token())
0101                 if spec:
0102                     (newfile, newstream) = spec
0103                     self.push_source(newstream, newfile)
0104                 raw = self.get_token()
0105         # Maybe we got EOF instead?
0106         while raw == self.eof:
0107             if not self.filestack:
0108                 return self.eof
0109             else:
0110                 self.pop_source()
0111                 raw = self.get_token()
0112         # Neither inclusion nor EOF
0113         if self.debug >= 1:
0114             if raw != self.eof:
0115                 print "shlex: token=" + repr(raw)
0116             else:
0117                 print "shlex: token=EOF"
0118         return raw
0119 
0120     def read_token(self):
0121         quoted = False
0122         escapedstate = ' '
0123         while True:
0124             nextchar = self.instream.read(1)
0125             if nextchar == '\n':
0126                 self.lineno = self.lineno + 1
0127             if self.debug >= 3:
0128                 print "shlex: in state", repr(self.state), \
0129                       "I see character:", repr(nextchar)
0130             if self.state is None:
0131                 self.token = ''        # past end of file
0132                 break
0133             elif self.state == ' ':
0134                 if not nextchar:
0135                     self.state = None  # end of file
0136                     break
0137                 elif nextchar in self.whitespace:
0138                     if self.debug >= 2:
0139                         print "shlex: I see whitespace in whitespace state"
0140                     if self.token or (self.posix and quoted):
0141                         break   # emit current token
0142                     else:
0143                         continue
0144                 elif nextchar in self.commenters:
0145                     self.instream.readline()
0146                     self.lineno = self.lineno + 1
0147                 elif self.posix and nextchar in self.escape:
0148                     escapedstate = 'a'
0149                     self.state = nextchar
0150                 elif nextchar in self.wordchars:
0151                     self.token = nextchar
0152                     self.state = 'a'
0153                 elif nextchar in self.quotes:
0154                     if not self.posix:
0155                         self.token = nextchar
0156                     self.state = nextchar
0157                 elif self.whitespace_split:
0158                     self.token = nextchar
0159                     self.state = 'a'
0160                 else:
0161                     self.token = nextchar
0162                     if self.token or (self.posix and quoted):
0163                         break   # emit current token
0164                     else:
0165                         continue
0166             elif self.state in self.quotes:
0167                 quoted = True
0168                 if not nextchar:      # end of file
0169                     if self.debug >= 2:
0170                         print "shlex: I see EOF in quotes state"
0171                     # XXX what error should be raised here?
0172                     raise ValueError, "No closing quotation"
0173                 if nextchar == self.state:
0174                     if not self.posix:
0175                         self.token = self.token + nextchar
0176                         self.state = ' '
0177                         break
0178                     else:
0179                         self.state = 'a'
0180                 elif self.posix and nextchar in self.escape and \
0181                      self.state in self.escapedquotes:
0182                     escapedstate = self.state
0183                     self.state = nextchar
0184                 else:
0185                     self.token = self.token + nextchar
0186             elif self.state in self.escape:
0187                 if not nextchar:      # end of file
0188                     if self.debug >= 2:
0189                         print "shlex: I see EOF in escape state"
0190                     # XXX what error should be raised here?
0191                     raise ValueError, "No escaped character"
0192                 # In posix shells, only the quote itself or the escape
0193                 # character may be escaped within quotes.
0194                 if escapedstate in self.quotes and \
0195                    nextchar != self.state and nextchar != escapedstate:
0196                     self.token = self.token + self.state
0197                 self.token = self.token + nextchar
0198                 self.state = escapedstate
0199             elif self.state == 'a':
0200                 if not nextchar:
0201                     self.state = None   # end of file
0202                     break
0203                 elif nextchar in self.whitespace:
0204                     if self.debug >= 2:
0205                         print "shlex: I see whitespace in word state"
0206                     self.state = ' '
0207                     if self.token or (self.posix and quoted):
0208                         break   # emit current token
0209                     else:
0210                         continue
0211                 elif nextchar in self.commenters:
0212                     self.instream.readline()
0213                     self.lineno = self.lineno + 1
0214                     if self.posix:
0215                         self.state = ' '
0216                         if self.token or (self.posix and quoted):
0217                             break   # emit current token
0218                         else:
0219                             continue
0220                 elif self.posix and nextchar in self.quotes:
0221                     self.state = nextchar
0222                 elif self.posix and nextchar in self.escape:
0223                     escapedstate = 'a'
0224                     self.state = nextchar
0225                 elif nextchar in self.wordchars or nextchar in self.quotes \
0226                     or self.whitespace_split:
0227                     self.token = self.token + nextchar
0228                 else:
0229                     self.pushback.appendleft(nextchar)
0230                     if self.debug >= 2:
0231                         print "shlex: I see punctuation in word state"
0232                     self.state = ' '
0233                     if self.token:
0234                         break   # emit current token
0235                     else:
0236                         continue
0237         result = self.token
0238         self.token = ''
0239         if self.posix and not quoted and result == '':
0240             result = None
0241         if self.debug > 1:
0242             if result:
0243                 print "shlex: raw token=" + repr(result)
0244             else:
0245                 print "shlex: raw token=EOF"
0246         return result
0247 
0248     def sourcehook(self, newfile):
0249         "Hook called on a filename to be sourced."
0250         if newfile[0] == '"':
0251             newfile = newfile[1:-1]
0252         # This implements cpp-like semantics for relative-path inclusion.
0253         if isinstance(self.infile, basestring) and not os.path.isabs(newfile):
0254             newfile = os.path.join(os.path.dirname(self.infile), newfile)
0255         return (newfile, open(newfile, "r"))
0256 
0257     def error_leader(self, infile=None, lineno=None):
0258         "Emit a C-compiler-like, Emacs-friendly error-message leader."
0259         if infile is None:
0260             infile = self.infile
0261         if lineno is None:
0262             lineno = self.lineno
0263         return "\"%s\", line %d: " % (infile, lineno)
0264 
0265     def __iter__(self):
0266         return self
0267 
0268     def next(self):
0269         token = self.get_token()
0270         if token == self.eof:
0271             raise StopIteration
0272         return token
0273 
0274 def split(s, comments=False):
0275     lex = shlex(s, posix=True)
0276     lex.whitespace_split = True
0277     if not comments:
0278         lex.commenters = ''
0279     return list(lex)
0280 
0281 if __name__ == '__main__':
0282     if len(sys.argv) == 1:
0283         lexer = shlex()
0284     else:
0285         file = sys.argv[1]
0286         lexer = shlex(open(file), file)
0287     while 1:
0288         tt = lexer.get_token()
0289         if tt:
0290             print "Token: " + repr(tt)
0291         else:
0292             break
0293 

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