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"""A lexical analyzer class for simple shell-like syntaxes."""
# Module and documentation by Eric S. Raymond, 21 Dec 1998
import sys
class shlex:
"A lexical analyzer class for simple shell-like syntaxes."
def __init__(self, instream=None):
if instream:
self.instream = instream
else:
self.instream = sys.stdin
self.commenters = '#'
self.wordchars = 'abcdfeghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_'
self.whitespace = ' \t\r\n'
self.quotes = '\'"'
self.state = ' '
self.pushback = [];
self.lineno = 1
self.debug = 0
self.token = ''
def push_token(self, tok):
"Push a token onto the stack popped by the get_token method"
if (self.debug >= 1):
print "Pushing " + tok
self.pushback = [tok] + self.pushback;
def get_token(self):
"Get a token from the input stream (or from stack if it's monempty)"
if self.pushback:
tok = self.pushback[0]
self.pushback = self.pushback[1:]
if (self.debug >= 1):
print "Popping " + tok
return tok
tok = ''
while 1:
nextchar = self.instream.read(1);
if nextchar == '\n':
self.lineno = self.lineno + 1
if self.debug >= 3:
print "In state " + repr(self.state) + " I see character: " + repr(nextchar)
if self.state == None:
return ''
elif self.state == ' ':
if not nextchar:
self.state = None; # end of file
break
elif nextchar in self.whitespace:
if self.debug >= 2:
print "I see whitespace in whitespace state"
if self.token:
break # emit current token
else:
continue
elif nextchar in self.commenters:
self.instream.readline()
self.lineno = self.lineno + 1
elif nextchar in self.wordchars:
self.token = nextchar
self.state = 'a'
elif nextchar in self.quotes:
self.token = nextchar
self.state = nextchar
else:
self.token = nextchar
if self.token:
break # emit current token
else:
continue
elif self.state in self.quotes:
self.token = self.token + nextchar
if nextchar == self.state:
self.state = ' '
break
elif self.state == 'a':
if not nextchar:
self.state = None; # end of file
break
elif nextchar in self.whitespace:
if self.debug >= 2:
print "I see whitespace in word state"
self.state = ' '
if self.token:
break # emit current token
else:
continue
elif nextchar in self.commenters:
self.instream.readline()
self.lineno = self.lineno + 1
elif nextchar in self.wordchars or nextchar in self.quotes:
self.token = self.token + nextchar
else:
self.pushback = [nextchar] + self.pushback
if self.debug >= 2:
print "I see punctuation in word state"
self.state = ' '
if self.token:
break # emit current token
else:
continue
result = self.token
self.token = ''
if self.debug >= 1:
print "Token: " + result
return result
if __name__ == '__main__':
lexer = shlex()
while 1:
tt = lexer.get_token()
if tt != None:
print "Token: " + repr(tt)
else:
break
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