| """A lexical analyzer class for simple shell-like syntaxes.""" |
| |
| # Module and documentation by Eric S. Raymond, 21 Dec 1998 |
| # Input stacking and error message cleanup added by ESR, March 2000 |
| # push_source() and pop_source() made explicit by ESR, January 2001. |
| |
| import os.path |
| import sys |
| |
| __all__ = ["shlex"] |
| |
| class shlex: |
| "A lexical analyzer class for simple shell-like syntaxes." |
| def __init__(self, instream=None, infile=None): |
| if instream is not None: |
| self.instream = instream |
| self.infile = infile |
| else: |
| self.instream = sys.stdin |
| self.infile = None |
| self.commenters = '#' |
| self.wordchars = ('abcdfeghijklmnopqrstuvwxyz' |
| 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_') |
| self.whitespace = ' \t\r\n' |
| self.quotes = '\'"' |
| self.state = ' ' |
| self.pushback = [] |
| self.lineno = 1 |
| self.debug = 0 |
| self.token = '' |
| self.filestack = [] |
| self.source = None |
| if self.debug: |
| print 'shlex: reading from %s, line %d' \ |
| % (self.instream, self.lineno) |
| |
| def push_token(self, tok): |
| "Push a token onto the stack popped by the get_token method" |
| if self.debug >= 1: |
| print "shlex: pushing token " + `tok` |
| self.pushback = [tok] + self.pushback |
| |
| def push_source(self, newstream, newfile=None): |
| "Push an input source onto the lexer's input source stack." |
| self.filestack.insert(0, (self.infile, self.instream, self.lineno)) |
| self.infile = newfile |
| self.instream = newstream |
| self.lineno = 1 |
| if self.debug: |
| if newfile is not None: |
| print 'shlex: pushing to file %s' % (self.infile,) |
| else: |
| print 'shlex: pushing to stream %s' % (self.instream,) |
| |
| def pop_source(self): |
| "Pop the input source stack." |
| self.instream.close() |
| (self.infile, self.instream, self.lineno) = self.filestack[0] |
| self.filestack = self.filestack[1:] |
| if self.debug: |
| print 'shlex: popping to %s, line %d' \ |
| % (self.instream, self.lineno) |
| self.state = ' ' |
| |
| def get_token(self): |
| "Get a token from the input stream (or from stack if it's nonempty)" |
| if self.pushback: |
| tok = self.pushback[0] |
| self.pushback = self.pushback[1:] |
| if self.debug >= 1: |
| print "shlex: popping token " + `tok` |
| return tok |
| # No pushback. Get a token. |
| raw = self.read_token() |
| # Handle inclusions |
| while raw == self.source: |
| spec = self.sourcehook(self.read_token()) |
| if spec: |
| (newfile, newstream) = spec |
| self.push_source(newstream, newfile) |
| raw = self.get_token() |
| # Maybe we got EOF instead? |
| while raw == "": |
| if len(self.filestack) == 0: |
| return "" |
| else: |
| self.pop_source() |
| raw = self.get_token() |
| # Neither inclusion nor EOF |
| if self.debug >= 1: |
| if raw: |
| print "shlex: token=" + `raw` |
| else: |
| print "shlex: token=EOF" |
| return raw |
| |
| def read_token(self): |
| "Read a token from the input stream (no pushback or inclusions)" |
| while 1: |
| nextchar = self.instream.read(1) |
| if nextchar == '\n': |
| self.lineno = self.lineno + 1 |
| if self.debug >= 3: |
| print "shlex: in state", repr(self.state), \ |
| "I see character:", repr(nextchar) |
| if self.state is None: |
| self.token = '' # past end of file |
| break |
| elif self.state == ' ': |
| if not nextchar: |
| self.state = None # end of file |
| break |
| elif nextchar in self.whitespace: |
| if self.debug >= 2: |
| print "shlex: 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 not nextchar: # end of file |
| if self.debug >= 2: |
| print "shlex: I see EOF in quotes state" |
| # XXX what error should be raised here? |
| raise ValueError, "No closing quotation" |
| elif self.state == 'a': |
| if not nextchar: |
| self.state = None # end of file |
| break |
| elif nextchar in self.whitespace: |
| if self.debug >= 2: |
| print "shlex: 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 "shlex: 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: |
| if result: |
| print "shlex: raw token=" + `result` |
| else: |
| print "shlex: raw token=EOF" |
| return result |
| |
| def sourcehook(self, newfile): |
| "Hook called on a filename to be sourced." |
| if newfile[0] == '"': |
| newfile = newfile[1:-1] |
| # This implements cpp-like semantics for relative-path inclusion. |
| if type(self.infile) == type("") and not os.path.isabs(newfile): |
| newfile = os.path.join(os.path.dirname(self.infile), newfile) |
| return (newfile, open(newfile, "r")) |
| |
| def error_leader(self, infile=None, lineno=None): |
| "Emit a C-compiler-like, Emacs-friendly error-message leader." |
| if infile is None: |
| infile = self.infile |
| if lineno is None: |
| lineno = self.lineno |
| return "\"%s\", line %d: " % (infile, lineno) |
| |
| |
| if __name__ == '__main__': |
| if len(sys.argv) == 1: |
| lexer = shlex() |
| else: |
| file = sys.argv[1] |
| lexer = shlex(open(file), file) |
| while 1: |
| tt = lexer.get_token() |
| if tt: |
| print "Token: " + repr(tt) |
| else: |
| break |