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/Lib/shlex.py

http://unladen-swallow.googlecode.com/
Python | 292 lines | 280 code | 5 blank | 7 comment | 11 complexity | b6d41f6a20bebc12cc556d80c2bc6fa8 MD5 | raw file
  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
 10import os.path
 11import sys
 12from collections import deque
 13
 14try:
 15    from cStringIO import StringIO
 16except ImportError:
 17    from StringIO import StringIO
 18
 19__all__ = ["shlex", "split"]
 20
 21class shlex:
 22    "A lexical analyzer class for simple shell-like syntaxes."
 23    def __init__(self, instream=None, infile=None, posix=False):
 24        if isinstance(instream, basestring):
 25            instream = StringIO(instream)
 26        if instream is not None:
 27            self.instream = instream
 28            self.infile = infile
 29        else:
 30            self.instream = sys.stdin
 31            self.infile = None
 32        self.posix = posix
 33        if posix:
 34            self.eof = None
 35        else:
 36            self.eof = ''
 37        self.commenters = '#'
 38        self.wordchars = ('abcdfeghijklmnopqrstuvwxyz'
 39                          'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_')
 40        if self.posix:
 41            self.wordchars += ('ßŕáâăäĺćçčéęëěíîďđńňóôőöřůúűüýţ˙'
 42                               'ŔÁÂĂÄĹĆÇČÉĘËĚÍÎĎĐŃŇÓÔŐÖŘŮÚŰÜÝŢ')
 43        self.whitespace = ' \t\r\n'
 44        self.whitespace_split = False
 45        self.quotes = '\'"'
 46        self.escape = '\\'
 47        self.escapedquotes = '"'
 48        self.state = ' '
 49        self.pushback = deque()
 50        self.lineno = 1
 51        self.debug = 0
 52        self.token = ''
 53        self.filestack = deque()
 54        self.source = None
 55        if self.debug:
 56            print 'shlex: reading from %s, line %d' \
 57                  % (self.instream, self.lineno)
 58
 59    def push_token(self, tok):
 60        "Push a token onto the stack popped by the get_token method"
 61        if self.debug >= 1:
 62            print "shlex: pushing token " + repr(tok)
 63        self.pushback.appendleft(tok)
 64
 65    def push_source(self, newstream, newfile=None):
 66        "Push an input source onto the lexer's input source stack."
 67        if isinstance(newstream, basestring):
 68            newstream = StringIO(newstream)
 69        self.filestack.appendleft((self.infile, self.instream, self.lineno))
 70        self.infile = newfile
 71        self.instream = newstream
 72        self.lineno = 1
 73        if self.debug:
 74            if newfile is not None:
 75                print 'shlex: pushing to file %s' % (self.infile,)
 76            else:
 77                print 'shlex: pushing to stream %s' % (self.instream,)
 78
 79    def pop_source(self):
 80        "Pop the input source stack."
 81        self.instream.close()
 82        (self.infile, self.instream, self.lineno) = self.filestack.popleft()
 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.popleft()
 92            if self.debug >= 1:
 93                print "shlex: popping token " + repr(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=" + repr(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.appendleft(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=" + repr(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
274def split(s, comments=False, posix=True):
275    lex = shlex(s, posix=posix)
276    lex.whitespace_split = True
277    if not comments:
278        lex.commenters = ''
279    return list(lex)
280
281if __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