不支持连续函数调用a.Func1().Func2()

```
rule "func_chain"
begin
data2=data.Filter("d1", "v1").HasGT(3)
end
```
类似这样的连续函数调用不支持，会直接报错 mismatched input '.' expecting END

Reproduce the reported func_chain rule with data.Filter("d1", "v1").HasGT(3) and inspect the parser or grammar entry point that reports "mismatched input '.' expecting END". Trace how a single function call is parsed and evaluated, then confirm that chained calls work without breaking existing rule syntax.

Written by the indexing model from the issue text.