Guido van Rossum | e7b146f | 2000-02-04 15:28:42 +0000 | [diff] [blame] | 1 | """A lexical analyzer class for simple shell-like syntaxes.""" |
| 2 | |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 3 | # Module and documentation by Eric S. Raymond, 21 Dec 1998 |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 4 | # Input stacking and error message cleanup added by ESR, March 2000 |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 5 | |
Guido van Rossum | 73898c7 | 1999-05-03 18:14:16 +0000 | [diff] [blame] | 6 | import sys |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 7 | |
| 8 | class shlex: |
| 9 | "A lexical analyzer class for simple shell-like syntaxes." |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 10 | def __init__(self, instream=None, infile=None): |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 11 | if instream: |
| 12 | self.instream = instream |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 13 | self.infile = infile |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 14 | else: |
| 15 | self.instream = sys.stdin |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 16 | self.infile = None |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 17 | self.commenters = '#' |
| 18 | self.wordchars = 'abcdfeghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_' |
| 19 | self.whitespace = ' \t\r\n' |
| 20 | self.quotes = '\'"' |
| 21 | self.state = ' ' |
| 22 | self.pushback = []; |
| 23 | self.lineno = 1 |
| 24 | self.debug = 0 |
| 25 | self.token = '' |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 26 | self.filestack = [] |
| 27 | self.source = None |
| 28 | if self.debug: |
| 29 | print 'shlex: reading from %s, line %d' % (self.instream,self.lineno) |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 30 | |
| 31 | def push_token(self, tok): |
| 32 | "Push a token onto the stack popped by the get_token method" |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 33 | if self.debug >= 1: |
| 34 | print "shlex: pushing token " + `tok` |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 35 | self.pushback = [tok] + self.pushback; |
| 36 | |
| 37 | def get_token(self): |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 38 | "Get a token from the input stream (or from stack if it's nonempty)" |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 39 | if self.pushback: |
| 40 | tok = self.pushback[0] |
| 41 | self.pushback = self.pushback[1:] |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 42 | if self.debug >= 1: |
| 43 | print "shlex: popping token " + `tok` |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 44 | return tok |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 45 | # No pushback. Get a token. |
| 46 | raw = self.read_token() |
| 47 | # Handle inclusions |
| 48 | while raw == self.source: |
| 49 | (newfile, newstream) = self.sourcehook(self.read_token()) |
| 50 | self.filestack = [(self.infile,self.instream,self.lineno)] + self.filestack |
| 51 | self.infile = newfile |
| 52 | self.instream = newstream |
| 53 | self.lineno = 1 |
| 54 | if self.debug: |
| 55 | print 'shlex: pushing to file %s' % (self.infile,) |
| 56 | raw = self.get_token() |
| 57 | # Maybe we got EOF instead? |
| 58 | while raw == "": |
| 59 | if len(self.filestack) == 0: |
| 60 | return "" |
| 61 | else: |
| 62 | self.instream.close() |
| 63 | (self.infile, self.instream, self.lineno) = self.filestack[0] |
| 64 | self.filestack = self.filestack[1:] |
| 65 | if self.debug: |
| 66 | print 'shlex: popping to %s, line %d' % (self.instream, self.lineno) |
| 67 | self.state = ' ' |
| 68 | raw = self.get_token() |
| 69 | # Neither inclusion nor EOF |
| 70 | if self.debug >= 1: |
| 71 | if raw: |
| 72 | print "shlex: token=" + `raw` |
| 73 | else: |
| 74 | print "shlex: token=EOF" |
| 75 | return raw |
| 76 | |
| 77 | def read_token(self): |
| 78 | "Read a token from the input stream (no pushback or inclusions)" |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 79 | tok = '' |
| 80 | while 1: |
| 81 | nextchar = self.instream.read(1); |
| 82 | if nextchar == '\n': |
| 83 | self.lineno = self.lineno + 1 |
| 84 | if self.debug >= 3: |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 85 | print "shlex: in state " + repr(self.state) + " I see character: " + repr(nextchar) |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 86 | if self.state == None: |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 87 | self.token = ''; # past end of file |
| 88 | break |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 89 | elif self.state == ' ': |
| 90 | if not nextchar: |
| 91 | self.state = None; # end of file |
| 92 | break |
| 93 | elif nextchar in self.whitespace: |
| 94 | if self.debug >= 2: |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 95 | print "shlex: I see whitespace in whitespace state" |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 96 | if self.token: |
| 97 | break # emit current token |
| 98 | else: |
| 99 | continue |
| 100 | elif nextchar in self.commenters: |
| 101 | self.instream.readline() |
| 102 | self.lineno = self.lineno + 1 |
| 103 | elif nextchar in self.wordchars: |
| 104 | self.token = nextchar |
| 105 | self.state = 'a' |
| 106 | elif nextchar in self.quotes: |
| 107 | self.token = nextchar |
| 108 | self.state = nextchar |
| 109 | else: |
| 110 | self.token = nextchar |
| 111 | if self.token: |
| 112 | break # emit current token |
| 113 | else: |
| 114 | continue |
| 115 | elif self.state in self.quotes: |
| 116 | self.token = self.token + nextchar |
| 117 | if nextchar == self.state: |
| 118 | self.state = ' ' |
| 119 | break |
| 120 | elif self.state == 'a': |
| 121 | if not nextchar: |
| 122 | self.state = None; # end of file |
| 123 | break |
| 124 | elif nextchar in self.whitespace: |
| 125 | if self.debug >= 2: |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 126 | print "shlex: I see whitespace in word state" |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 127 | self.state = ' ' |
| 128 | if self.token: |
| 129 | break # emit current token |
| 130 | else: |
| 131 | continue |
| 132 | elif nextchar in self.commenters: |
| 133 | self.instream.readline() |
| 134 | self.lineno = self.lineno + 1 |
| 135 | elif nextchar in self.wordchars or nextchar in self.quotes: |
| 136 | self.token = self.token + nextchar |
| 137 | else: |
| 138 | self.pushback = [nextchar] + self.pushback |
| 139 | if self.debug >= 2: |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 140 | print "shlex: I see punctuation in word state" |
Guido van Rossum | f247d75 | 1999-03-22 15:28:08 +0000 | [diff] [blame] | 141 | self.state = ' ' |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 142 | if self.token: |
| 143 | break # emit current token |
| 144 | else: |
| 145 | continue |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 146 | result = self.token |
| 147 | self.token = '' |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 148 | if self.debug > 1: |
| 149 | if result: |
| 150 | print "shlex: raw token=" + `result` |
| 151 | else: |
| 152 | print "shlex: raw token=EOF" |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 153 | return result |
| 154 | |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 155 | def sourcehook(self, newfile): |
| 156 | "Hook called on a filename to be sourced." |
| 157 | if newfile[0] == '"': |
| 158 | newfile = newfile[1:-1] |
| 159 | return (newfile, open(newfile, "r")) |
| 160 | |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 161 | if __name__ == '__main__': |
| 162 | |
| 163 | lexer = shlex() |
| 164 | while 1: |
| 165 | tt = lexer.get_token() |
Guido van Rossum | eb4e11a | 2000-05-01 20:08:46 +0000 | [diff] [blame^] | 166 | print "Token: " + repr(tt) |
| 167 | if not tt: |
Guido van Rossum | 9c30c24 | 1998-12-22 05:19:29 +0000 | [diff] [blame] | 168 | break |
| 169 | |