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 ------------------运算符的语法做了一些修订，给出了更简单的规则：以 . 为开头的运算符有可能还包含其它 . 在里面，比如..或...，这种情况下后面连续的 . 也并入运算符本身，所以x....foo中的运算符应该是...，而不是(x)(...)(.foo)或其它。如果运算符不以 . 开头，比如&%^，那么&%^.后面的 . 就不属于此运算符，它属于.foo(foo为枚举成员)。