Resolve syntactic ambiguity between invocations and boolean expressions #46
Description
Take the following statement as an example: a<b>(c). Syntactically, this statement can be parsed by the following two rules:
- A boolean expression comparing
a,b, andc. - An invocation of function
a, with a parameter calledcand a placeholder calledb.
Admittedly, it is rather rare to place a single operand inside parentheses; however, since Rouge is an educational language, it should not be ruled out that a user might want to write a program containing an expression like that.
Technically, this ambiguity can be resolved during static analysis by checking whether a is saved in the symbol table as a function or not. However, this still wouldn't work when a is meant to be invoked but has not been defined. In this case, the interpreter would run the static analysis for boolean expressions, even though the user intended to perform a function call.
Therefore, this ambiguity should be resolved on the syntactic level. One solution to this problem involves forcing the user to use parenthesis when chaining multiple operators in a single boolean expression. For instance, the above statement (if it were intended to be a boolean expression) would have to be rewritten like so:
(a<b)>(c) or a<(b>c)