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')
def ReadWord(self, unused_lex_mode):
if self.i == self.n:
# NOTE: Could define something special
return ast.StringWord(Id.Eof_Real, '')
#log('ARGV %s i %d', self.argv, self.i)
s = self.argv[self.i]
self.i += 1
# default is an operand word
id_ = (_UNARY_LOOKUP.get(s) or _BINARY_LOOKUP.get(s)
or _OTHER_LOOKUP.get(s) or Id.Word_Compound)
return ast.StringWord(id_, s)
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', a0)
child = ast.StringWord(Id.Word_Compound, a1)
return ast.BoolUnary(unary_id, child)
def _StringWordTest(s):
# TODO: Could be Word_String
return ast.WordTest(ast.StringWord(Id.Word_Compound, s))