def _ThreeArgs(argv):
"""Returns an expression tree to be evaluated."""
a0, a1, a2 = argv
# NOTE: Order is important here.
binary_id = _BINARY_LOOKUP.get(a1)
if binary_id is not None:
left = ast.StringWord(Id.Word_Compound, a0)
right = ast.StringWord(Id.Word_Compound, a2)
return ast.BoolBinary(binary_id, left, right)
if a1 == '-a':
left = _StringWordTest(a0)
right = _StringWordTest(a2)
return ast.LogicalAnd(left, right)
if a1 == '-o':
left = _StringWordTest(a0)
right = _StringWordTest(a2)
return ast.LogicalOr(left, right)
if a0 == '!':
child = _TwoArgs(argv[1:])
return ast.LogicalNot(child)
if a0 == '(' and a2 == ')':
return _StringWordTest(a1)
util.p_die('Syntax error: binary operator expected, got %r (3 args)', a1)
def ParseNegatedFactor(self):
"""
Negated : '!'? Factor
"""
if self.op_id == Id.KW_Bang:
self._Next()
child = self.ParseFactor()
return ast.LogicalNot(child)
else:
return self.ParseFactor()
def ParseNegatedFactor(self):
"""
Negated : '!'? Factor
"""
if self.op_id == Id.KW_Bang:
if not self._Next(): return None
child = self.ParseFactor()
if not child: return None
return ast.LogicalNot(child)
else:
return self.ParseFactor()
def _TwoArgs(argv):
"""Returns an expression tree to be evaluated."""
a0, a1 = argv
if a0 == '!':
return ast.LogicalNot(_StringWordTest(a1))
unary_id = _UNARY_LOOKUP.get(a0)
if unary_id is None:
# TODO:
# - syntax error
# - separate lookup by unary
util.p_die('Expected unary operator, got %r (2 args)', a0)
child = ast.StringWord(Id.Word_Compound, a1)
return ast.BoolUnary(unary_id, child)
def Test(argv, need_right_bracket):
"""The test/[ builtin.
The only difference between test and [ is that [ needs a matching ].
"""
if need_right_bracket:
if not argv or argv[-1] != ']':
util.error('[: missing closing ]')
return 2
del argv[-1]
w_parser = _StringWordEmitter(argv)
b_parser = bool_parse.BoolParser(w_parser)
# There is a fundamental ambiguity due to poor language design, in cases like:
# [ -z ]
# [ -z -a ]
# [ -z -a ] ]
#
# See posixtest() in bash's test.c:
# "This is an implementation of a Posix.2 proposal by David Korn."
# It dispatches on expressions of length 0, 1, 2, 3, 4, and N args. We do
# the same here.
#
# Another ambiguity:
# -a is both a unary prefix operator and an infix operator. How to fix this
# ambiguity?
bool_node = None
n = len(argv)
try:
if n == 0:
return 1 # [ ] is False
elif n == 1:
bool_node = _StringWordTest(argv[0])
elif n == 2:
bool_node = _TwoArgs(argv)
elif n == 3:
bool_node = _ThreeArgs(argv)
if n == 4:
a0 = argv[0]
if a0 == '!':
child = _ThreeArgs(argv[1:])
bool_node = ast.LogicalNot(child)
elif a0 == '(' and argv[3] == ')':
bool_node = _TwoArgs(argv[1:3])
else:
pass # fallthrough
if bool_node is None:
bool_node = b_parser.ParseForBuiltin()
except util.ParseError as e:
# TODO: There should be a nice method to print argv. And some way to point
# to the error.
log("Error parsing %s", argv)
util.error("test: %s", e.UserErrorString())
return 2 # parse error is 2
# mem: Don't need it for BASH_REMATCH? Or I guess you could support it
# exec_opts: don't need it, but might need it later
mem = None # Not necessary
word_ev = _WordEvaluator()
arena = None
# We want [ a -eq a ] to always be an error, unlike [[ a -eq a ]]. This is a
# weird case of [[ being less strict.
class _DummyExecOpts():
def __init__(self):
self.strict_arith = True
exec_opts = _DummyExecOpts()
bool_ev = expr_eval.BoolEvaluator(mem, exec_opts, word_ev, arena)
try:
b = bool_ev.Eval(bool_node)
except util.FatalRuntimeError as e:
# e.g. [ -t xxx ]
# TODO: Printing the location would be nice.
util.error('test: %s', e.UserErrorString())
return 2 # because this is more like a parser error.
status = 0 if b else 1
return status
