"""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.
# Posix compliance, split(), string arguments, and
# iterator interface by Gustavo Niemeyer, April 2003.
import os
import re
import sys
from collections import deque
from io import StringIO
__all__ = ["shlex", "split", "quote"]
class shlex:
"A lexical analyzer class for simple shell-like syntaxes."
def __init__(self, instream=None, infile=None, posix=False):
if isinstance(instream, str):
instream = StringIO(instream)
if instream is not None:
self.instream = instream
self.infile = infile
else:
self.instream = sys.stdin
self.infile = None
self.posix = posix
if posix:
self.eof = None
else:
self.eof = ''
self.commenters = '#'
self.wordchars = ('abcdfeghijklmnopqrstuvwxyz'
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_')
if self.posix:
self.wordchars += ('ßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'
'ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞ')
self.whitespace = ' \t\r\n'
self.whitespace_split = False
self.quotes = '\'"'
self.escape = '\\'
self.escapedquotes = '"'
self.state = ' '
self.pushback = deque()
self.lineno = 1
self.debug = 0
self.token = ''
self.filestack = deque()
self.source = None
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 " + repr(tok))
self.pushback.appendleft(tok)
def push_source(self, newstream, newfile=None):
"Push an input source onto the lexer's input source stack."
if isinstance(newstream, str):
newstream = StringIO(newstream)
self.filestack.appendleft((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.popleft()
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.popleft()
if self.debug >= 1:
print("shlex: popping token " + repr(tok))
return tok
# No pushback. Get a token.
raw = self.read_token()
# Handle inclusions
if self.source is not None:
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 == self.eof:
if not self.filestack:
return self.eof
else:
self.pop_source()
raw = self.get_token()
# Neither inclusion nor EOF
if self.debug >= 1:
if raw != self.eof:
print("shlex: token=" + repr(raw))
else:
print("shlex: token=EOF")
return raw
def read_token(self):
quoted = False
escapedstate = ' '
while True:
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 or (self.posix and quoted):
break # emit current token
else:
continue
elif nextchar in self.commenters:
self.instream.readline()
self.lineno = self.lineno + 1
elif self.posix and nextchar in self.escape:
escapedstate = 'a'
self.state = nextchar
elif nextchar in self.wordchars:
self.token = nextchar
self.state = 'a'
elif nextchar in self.quotes:
if not self.posix:
self.token = nextchar
self.state = nextchar
elif self.whitespace_split:
self.token = nextchar
self.state = 'a'
else:
self.token = nextchar
if self.token or (self.posix and quoted):
break # emit current token
else:
continue
elif self.state in self.quotes:
quoted = True
if 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")
if nextchar == self.state:
if not self.posix:
self.token = self.token + nextchar
self.state = ' '
break
else:
self.state = 'a'
elif self.posix and nextchar in self.escape and \
self.state in self.escapedquotes:
escapedstate = self.state
self.state = nextchar
else:
self.token = self.token + nextchar
elif self.state in self.escape:
if not nextchar: # end of file
if self.debug >= 2:
print("shlex: I see EOF in escape state")
# XXX what error should be raised here?
raise ValueError("No escaped character")
# In posix shells, only the quote itself or the escape
# character may be escaped within quotes.
if escapedstate in self.quotes and \
nextchar != self.state and nextchar != escapedstate:
self.token = self.token + self.state
self.token = self.token + nextchar
self.state = escapedstate
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 or (self.posix and quoted):
break # emit current token
else:
continue
elif nextchar in self.commenters:
self.instream.readline()
self.lineno = self.lineno + 1
if self.posix:
self.state = ' '
if self.token or (self.posix and quoted):
break # emit current token
else:
continue
elif self.posix and nextchar in self.quotes:
self.state = nextchar
elif self.posix and nextchar in self.escape:
escapedstate = 'a'
self.state = nextchar
elif nextchar in self.wordchars or nextchar in self.quotes \
or self.whitespace_split:
self.token = self.token + nextchar
else:
self.pushback.appendleft(nextchar)
if self.debug >= 2:
print("shlex: I see punctuation in word state")
self.state = ' '
if self.token or (self.posix and quoted):
break # emit current token
else:
continue
result = self.token
self.token = ''
if self.posix and not quoted and result == '':
result = None
if self.debug > 1:
if result:
print("shlex: raw token=" + repr(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 isinstance(self.infile, str) 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)
def __iter__(self):
return self
def __next__(self):
token = self.get_token()
if token == self.eof:
raise StopIteration
return token
def split(s, comments=False, posix=True):
lex = shlex(s, posix=posix)
lex.whitespace_split = True
if not comments:
lex.commenters = ''
return list(lex)
_find_unsafe = re.compile(r'[^\w@%+=:,./-]', re.ASCII).search
def quote(s):
"""Return a shell-escaped version of the string *s*."""
if not s:
return "''"
if _find_unsafe(s) is None:
return s
# use single quotes, and put single quotes into double quotes
# the string $'b is then quoted as '$'"'"'b'
return "'" + s.replace("'", "'\"'\"'") + "'"
def _print_tokens(lexer):
while 1:
tt = lexer.get_token()
if not tt:
break
print("Token: " + repr(tt))
if __name__ == '__main__':
if len(sys.argv) == 1:
_print_tokens(shlex())
else:
fn = sys.argv[1]
with open(fn) as f:
_print_tokens(shlex(f, fn))
