The operator identifier lexer grammar has been revised to simplify the rules
for operators that start with a dot ("."). The new rule is that an operator
that starts with a dot may contain other dots in it, but operators that start
with some other character may not contain dots. For example:

x....foo --> "x" "...." "foo" x&%^.foo --> "x" "&%^" ".foo" ----------------- 分割线 ------------------