Lib/shlex.py

   1 # -*- coding: iso-8859-1 -*-
   2 """A lexical analyzer class for simple shell-like syntaxes."""
   3
   4 # Module and documentation by Eric S. Raymond, 21 Dec 1998
   5 # Input stacking and error message cleanup added by ESR, March 2000
   6 # push_source() and pop_source() made explicit by ESR, January 2001.
   7 # Posix compliance, split(), string arguments, and
   8 # iterator interface by Gustavo Niemeyer, April 2003.
   9
  10 import os.path
  11 import sys
  12
  13 try:
  14     from cStringIO import StringIO
  15 except ImportError:
  16     from StringIO import StringIO
  17
  18 __all__ = ["shlex", "split"]
  19
  20 class shlex:
  21     "A lexical analyzer class for simple shell-like syntaxes."
  22     def __init__(self, instream=None, infile=None, posix=False):
  23         if isinstance(instream, basestring):
  24             instream = StringIO(instream)
  25         if instream is not None:
  26             self.instream = instream
  27             self.infile = infile
  28         else:
  29             self.instream = sys.stdin
  30             self.infile = None
  31         self.posix = posix
  32         if posix:
  33             self.eof = None
  34         else:
  35             self.eof = ''
  36         self.commenters = '#'
  37         self.wordchars = ('abcdfeghijklmnopqrstuvwxyz'
  38                           'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_')
  39         if self.posix:
  40             self.wordchars += ('ßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'
  41                                'ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞ')
  42         self.whitespace = ' \t\r\n'
  43         self.whitespace_split = False
  44         self.quotes = '\'"'
  45         self.escape = '\\'
  46         self.escapedquotes = '"'
  47         self.state = ' '
  48         self.pushback = []
  49         self.lineno = 1
  50         self.debug = 0
  51         self.token = ''
  52         self.filestack = []
  53         self.source = None
  54         if self.debug:
  55             print 'shlex: reading from %s, line %d' \
  56                   % (self.instream, self.lineno)
  57
  58     def push_token(self, tok):
  59         "Push a token onto the stack popped by the get_token method"
  60         if self.debug >= 1:
  61             print "shlex: pushing token " + `tok`
  62         self.pushback.insert(0, tok)
  63
  64     def push_source(self, newstream, newfile=None):
  65         "Push an input source onto the lexer's input source stack."
  66         if isinstance(newstream, basestring):
  67             newstream = StringIO(newstream)
  68         self.filestack.insert(0, (self.infile, self.instream, self.lineno))
  69         self.infile = newfile
  70         self.instream = newstream
  71         self.lineno = 1
  72         if self.debug:
  73             if newfile is not None:
  74                 print 'shlex: pushing to file %s' % (self.infile,)
  75             else:
  76                 print 'shlex: pushing to stream %s' % (self.instream,)
  77
  78     def pop_source(self):
  79         "Pop the input source stack."
  80         self.instream.close()
  81         (self.infile, self.instream, self.lineno) = self.filestack[0]
  82         self.filestack = self.filestack[1:]
  83         if self.debug:
  84             print 'shlex: popping to %s, line %d' \
  85                   % (self.instream, self.lineno)
  86         self.state = ' '
  87
  88     def get_token(self):
  89         "Get a token from the input stream (or from stack if it's nonempty)"
  90         if self.pushback:
  91             tok = self.pushback.pop(0)
  92             if self.debug >= 1:
  93                 print "shlex: popping token " + `tok`
  94             return tok
  95         # No pushback.  Get a token.
  96         raw = self.read_token()
  97         # Handle inclusions
  98         if self.source is not None:
  99             while raw == self.source:
 100                 spec = self.sourcehook(self.read_token())
 101                 if spec:
 102                     (newfile, newstream) = spec
 103                     self.push_source(newstream, newfile)
 104                 raw = self.get_token()
 105         # Maybe we got EOF instead?
 106         while raw == self.eof:
 107             if not self.filestack:
 108                 return self.eof
 109             else:
 110                 self.pop_source()
 111                 raw = self.get_token()
 112         # Neither inclusion nor EOF
 113         if self.debug >= 1:
 114             if raw != self.eof:
 115                 print "shlex: token=" + `raw`
 116             else:
 117                 print "shlex: token=EOF"
 118         return raw
 119
 120     def read_token(self):
 121         quoted = False
 122         escapedstate = ' '
 123         while True:
 124             nextchar = self.instream.read(1)
 125             if nextchar == '\n':
 126                 self.lineno = self.lineno + 1
 127             if self.debug >= 3:
 128                 print "shlex: in state", repr(self.state), \
 129                       "I see character:", repr(nextchar)
 130             if self.state is None:
 131                 self.token = ''        # past end of file
 132                 break
 133             elif self.state == ' ':
 134                 if not nextchar:
 135                     self.state = None  # end of file
 136                     break
 137                 elif nextchar in self.whitespace:
 138                     if self.debug >= 2:
 139                         print "shlex: I see whitespace in whitespace state"
 140                     if self.token or (self.posix and quoted):
 141                         break   # emit current token
 142                     else:
 143                         continue
 144                 elif nextchar in self.commenters:
 145                     self.instream.readline()
 146                     self.lineno = self.lineno + 1
 147                 elif self.posix and nextchar in self.escape:
 148                     escapedstate = 'a'
 149                     self.state = nextchar
 150                 elif nextchar in self.wordchars:
 151                     self.token = nextchar
 152                     self.state = 'a'
 153                 elif nextchar in self.quotes:
 154                     if not self.posix:
 155                         self.token = nextchar
 156                     self.state = nextchar
 157                 elif self.whitespace_split:
 158                     self.token = nextchar
 159                     self.state = 'a'
 160                 else:
 161                     self.token = nextchar
 162                     if self.token or (self.posix and quoted):
 163                         break   # emit current token
 164                     else:
 165                         continue
 166             elif self.state in self.quotes:
 167                 quoted = True
 168                 if not nextchar:      # end of file
 169                     if self.debug >= 2:
 170                         print "shlex: I see EOF in quotes state"
 171                     # XXX what error should be raised here?
 172                     raise ValueError, "No closing quotation"
 173                 if nextchar == self.state:
 174                     if not self.posix:
 175                         self.token = self.token + nextchar
 176                         self.state = ' '
 177                         break
 178                     else:
 179                         self.state = 'a'
 180                 elif self.posix and nextchar in self.escape and \
 181                      self.state in self.escapedquotes:
 182                     escapedstate = self.state
 183                     self.state = nextchar
 184                 else:
 185                     self.token = self.token + nextchar
 186             elif self.state in self.escape:
 187                 if not nextchar:      # end of file
 188                     if self.debug >= 2:
 189                         print "shlex: I see EOF in escape state"
 190                     # XXX what error should be raised here?
 191                     raise ValueError, "No escaped character"
 192                 # In posix shells, only the quote itself or the escape
 193                 # character may be escaped within quotes.
 194                 if escapedstate in self.quotes and \
 195                    nextchar != self.state and nextchar != escapedstate:
 196                     self.token = self.token + self.state
 197                 self.token = self.token + nextchar
 198                 self.state = escapedstate
 199             elif self.state == 'a':
 200                 if not nextchar:
 201                     self.state = None   # end of file
 202                     break
 203                 elif nextchar in self.whitespace:
 204                     if self.debug >= 2:
 205                         print "shlex: I see whitespace in word state"
 206                     self.state = ' '
 207                     if self.token or (self.posix and quoted):
 208                         break   # emit current token
 209                     else:
 210                         continue
 211                 elif nextchar in self.commenters:
 212                     self.instream.readline()
 213                     self.lineno = self.lineno + 1
 214                     if self.posix:
 215                         self.state = ' '
 216                         if self.token or (self.posix and quoted):
 217                             break   # emit current token
 218                         else:
 219                             continue
 220                 elif self.posix and nextchar in self.quotes:
 221                     self.state = nextchar
 222                 elif self.posix and nextchar in self.escape:
 223                     escapedstate = 'a'
 224                     self.state = nextchar
 225                 elif nextchar in self.wordchars or nextchar in self.quotes \
 226                     or self.whitespace_split:
 227                     self.token = self.token + nextchar
 228                 else:
 229                     self.pushback.insert(0, nextchar)
 230                     if self.debug >= 2:
 231                         print "shlex: I see punctuation in word state"
 232                     self.state = ' '
 233                     if self.token:
 234                         break   # emit current token
 235                     else:
 236                         continue
 237         result = self.token
 238         self.token = ''
 239         if self.posix and not quoted and result == '':
 240             result = None
 241         if self.debug > 1:
 242             if result:
 243                 print "shlex: raw token=" + `result`
 244             else:
 245                 print "shlex: raw token=EOF"
 246         return result
 247
 248     def sourcehook(self, newfile):
 249         "Hook called on a filename to be sourced."
 250         if newfile[0] == '"':
 251             newfile = newfile[1:-1]
 252         # This implements cpp-like semantics for relative-path inclusion.
 253         if isinstance(self.infile, basestring) and not os.path.isabs(newfile):
 254             newfile = os.path.join(os.path.dirname(self.infile), newfile)
 255         return (newfile, open(newfile, "r"))
 256
 257     def error_leader(self, infile=None, lineno=None):
 258         "Emit a C-compiler-like, Emacs-friendly error-message leader."
 259         if infile is None:
 260             infile = self.infile
 261         if lineno is None:
 262             lineno = self.lineno
 263         return "\"%s\", line %d: " % (infile, lineno)
 264
 265     def __iter__(self):
 266         return self
 267
 268     def next(self):
 269         token = self.get_token()
 270         if token == self.eof:
 271             raise StopIteration
 272         return token
 273
 274 def split(s, comments=False):
 275     lex = shlex(s, posix=True)
 276     lex.whitespace_split = True
 277     if not comments:
 278         lex.commenters = ''
 279     return list(lex)
 280
 281 if __name__ == '__main__':
 282     if len(sys.argv) == 1:
 283         lexer = shlex()
 284     else:
 285         file = sys.argv[1]
 286         lexer = shlex(open(file), file)
 287     while 1:
 288         tt = lexer.get_token()
 289         if tt:
 290             print "Token: " + repr(tt)
 291         else:
 292             break