need examples to understand postfix expression grammar

[FabArd]

I am trying to put the D grammar rules into tree-sitter in order 
to understand how it works and to deepen my knowledge of the D 
language.

So how to determine the following expressions:

1   Window window = Platform.instance.createWindow("Bezier 
curves", 300, 500);
2   window.show();
3   return Platform.instance.enterMessageLoop();
4   Point sz = font.textSize(text);

My problem is that all these expressions are interpreted with 
"type conversion" expression rule and not function call 
expression rule.

How to distinguish a function call expression from a "type 
conversion" expression?
Knowing that the two rules can be applied to all these 
expressions.

To solve part of my problem a solution would be to be able to 
restrict a rule to its strict minimum. This is why I made the 
previous proposal.

Is it correct to restrict this rule as I propose?
If possible, line 1 of the above examples becomes a function call 
expression.
If not can you give me examples of type conversion expression 
with a list of arguments.

Would there be a safe way to determine a function call expression 
from a type conversion expression?

Thanks