| # 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 |
| |