from __future__ import absolute_import
import itertools
import lit.util
from lit.ShCommands import Command, GlobItem, Pipeline, Seq
class ShLexer:
def __init__(self, data, win32Escapes=False):
self.data = data
self.pos = 0
self.end = len(data)
self.win32Escapes = win32Escapes
def eat(self):
c = self.data[self.pos]
self.pos += 1
return c
def look(self):
return self.data[self.pos]
def maybe_eat(self, c):
"""
maybe_eat(c) - Consume the character c if it is the next character,
returning True if a character was consumed."""
if self.data[self.pos] == c:
self.pos += 1
return True
return False
def lex_arg_fast(self, c):
# Get the leading whitespace free section.
chunk = self.data[self.pos - 1 :].split(None, 1)[0]
# If it has special characters, the fast path failed.
if (
"|" in chunk
or "&" in chunk
or "<" in chunk
or ">" in chunk
or "'" in chunk
or '"' in chunk
or ";" in chunk
or "\\" in chunk
):
return None
self.pos = self.pos - 1 + len(chunk)
return GlobItem(chunk) if "*" in chunk or "?" in chunk else chunk
def lex_arg_slow(self, c):
if c in "'\"":
str = self.lex_arg_quoted(c)
else:
str = c
unquoted_glob_char = False
quoted_glob_char = False
while self.pos != self.end:
c = self.look()
if c.isspace() or c in "|&;":
break
elif c in "><":
# This is an annoying case; we treat '2>' as a single token so
# we don't have to track whitespace tokens.
# If the parse string isn't an integer, do the usual thing.
if not str.isdigit():
break
# Otherwise, lex the operator and convert to a redirection
# token.
num = int(str)
tok = self.lex_one_token()
assert isinstance(tok, tuple) and len(tok) == 1
return (tok[0], num)
elif c == '"' or c == "'":
self.eat()
quoted_arg = self.lex_arg_quoted(c)
if "*" in quoted_arg or "?" in quoted_arg:
quoted_glob_char = True
str += quoted_arg
elif not self.win32Escapes and c == "\\":
# Outside of a string, '\\' escapes everything.
self.eat()
if self.pos == self.end:
lit.util.warning(
"escape at end of quoted argument in: %r" % self.data
)
return str
str += self.eat()
elif c in "*?":
unquoted_glob_char = True
str += self.eat()
else:
str += self.eat()
# If a quote character is present, lex_arg_quoted will remove the quotes
# and append the argument directly. This causes a problem when the
# quoted portion contains a glob character, as the character will no
# longer be treated literally. If glob characters occur *only* inside
# of quotes, then we can handle this by not globbing at all, and if
# glob characters occur *only* outside of quotes, we can still glob just
# fine. But if a glob character occurs both inside and outside of
# quotes this presents a problem. In practice this is such an obscure
# edge case that it doesn't seem worth the added complexity to support.
# By adding an assertion, it means some bot somewhere will catch this
# and flag the user of a non-portable test (which could almost certainly
# be re-written to work correctly without triggering this).
assert not (quoted_glob_char and unquoted_glob_char)
return GlobItem(str) if unquoted_glob_char else str
def lex_arg_quoted(self, delim):
str = ""
while self.pos != self.end:
c = self.eat()
if c == delim:
return str
elif c == "\\" and delim == '"':
# Inside a '"' quoted string, '\\' only escapes the quote
# character and backslash, otherwise it is preserved.
if self.pos == self.end:
lit.util.warning(
"escape at end of quoted argument in: %r" % self.data
)
return str
c = self.eat()
if c == '"': #
str += '"'
elif c == "\\":
str += "\\"
else:
str += "\\" + c
else:
str += c
lit.util.warning("missing quote character in %r" % self.data)
return str
def lex_arg_checked(self, c):
pos = self.pos
res = self.lex_arg_fast(c)
end = self.pos
self.pos = pos
reference = self.lex_arg_slow(c)
if res is not None:
if res != reference:
raise ValueError("Fast path failure: %r != %r" % (res, reference))
if self.pos != end:
raise ValueError("Fast path failure: %r != %r" % (self.pos, end))
return reference
def lex_arg(self, c):
return self.lex_arg_fast(c) or self.lex_arg_slow(c)
def lex_one_token(self):
"""
lex_one_token - Lex a single 'sh' token."""
c = self.eat()
if c == ";":
return (c,)
if c == "|":
if self.maybe_eat("|"):
return ("||",)
return (c,)
if c == "&":
if self.maybe_eat("&"):
return ("&&",)
if self.maybe_eat(">"):
return ("&>",)
return (c,)
if c == ">":
if self.maybe_eat("&"):
return (">&",)
if self.maybe_eat(">"):
return (">>",)
return (c,)
if c == "<":
if self.maybe_eat("&"):
return ("<&",)
if self.maybe_eat(">"):
return ("<<",)
return (c,)
return self.lex_arg(c)
def lex(self):
while self.pos != self.end:
if self.look().isspace():
self.eat()
else:
yield self.lex_one_token()
###
class ShParser:
def __init__(self, data, win32Escapes=False, pipefail=False):
self.data = data
self.pipefail = pipefail
self.tokens = ShLexer(data, win32Escapes=win32Escapes).lex()
def lex(self):
for item in self.tokens:
return item
return None
def look(self):
token = self.lex()
if token is not None:
self.tokens = itertools.chain([token], self.tokens)
return token
def parse_command(self):
tok = self.lex()
if not tok:
raise ValueError("empty command!")
if isinstance(tok, tuple):
raise ValueError("syntax error near unexpected token %r" % tok[0])
args = [tok]
redirects = []
while 1:
tok = self.look()
# EOF?
if tok is None:
break
# If this is an argument, just add it to the current command.
if isinstance(tok, (str, GlobItem)):
args.append(self.lex())
continue
# Otherwise see if it is a terminator.
assert isinstance(tok, tuple)
if tok[0] in ("|", ";", "&", "||", "&&"):
break
# Otherwise it must be a redirection.
op = self.lex()
arg = self.lex()
if not arg:
raise ValueError("syntax error near token %r" % op[0])
redirects.append((op, arg))
return Command(args, redirects)
def parse_pipeline(self):
negate = False
commands = [self.parse_command()]
while self.look() == ("|",):
self.lex()
commands.append(self.parse_command())
return Pipeline(commands, negate, self.pipefail)
def parse(self):
lhs = self.parse_pipeline()
while self.look():
operator = self.lex()
assert isinstance(operator, tuple) and len(operator) == 1
if not self.look():
raise ValueError("missing argument to operator %r" % operator[0])
# FIXME: Operator precedence!!
lhs = Seq(lhs, operator[0], self.parse_pipeline())
return lhs
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