def _ReadArithSub2Part(self):
"""Non-standard arith sub $[a + 1]."""
left_span_id = self.cur_token.span_id
anode = self._ReadArithExpr()
if not anode:
self.AddErrorContext("Error parsing arith sub part")
return None
if self.token_type != Id.Arith_RBracket:
self.AddErrorContext("Expected ], got %s", self.cur_token)
return None
right_span_id = self.cur_token.span_id
node = ast.ArithSubPart(anode)
node.spids.append(left_span_id)
node.spids.append(right_span_id)
return node
def _ReadArithSubPart(self):
"""
Read an arith substitution, which contains an arith expression, e.g.
$((a + 1)).
"""
left_span_id = self.cur_token.span_id
# The second one needs to be disambiguated in stuff like stuff like:
# $(echo $(( 1+2 )) )
self.lexer.PushHint(Id.Op_RParen, Id.Right_ArithSub)
# NOTE: To disambiguate $(( as arith sub vs. command sub and subshell, we
# could save the lexer/reader state here, and retry if the arithmetic parse
# fails. But we can almost always catch this at parse time. There could
# be some exceptions like:
# $((echo * foo)) # looks like multiplication
# $((echo / foo)) # looks like division
anode = self._ReadArithExpr()
if not anode:
self.AddErrorContext("Error parsing arith sub part")
return None
if self.token_type != Id.Arith_RParen:
self._BadToken('Expected first paren to end arith sub, got %s',
self.cur_token)
return None
self._Next(LexMode.OUTER) # TODO: This could be DQ or ARITH too
# PROBLEM: $(echo $(( 1 + 2 )) )
# Two right parens break the Id.Eof_RParen scheme
self._Peek()
if self.token_type != Id.Right_ArithSub:
self._BadToken('Expected second paren to end arith sub, got %s',
self.cur_token)
return None
right_span_id = self.cur_token.span_id
node = ast.ArithSubPart(anode)
node.spids.append(left_span_id)
node.spids.append(right_span_id)
return node