[antlr-interest] Expressions
Peter Ashford
kaffiene at xtra.co.nz
Thu Aug 5 13:56:45 PDT 2004
Sebastian Kaliszewski wrote:
>Peter Ashford wrote:
>
>
>>Whats the recommended way to handle expressions when you can have
>>several different kinds of expression (I'm wanting float, string and
>>boolean expressions)?
>>
>>
>
>Standard way is to parse everything just as expression and only in one of
>the following compilation phase -- type determination & checking -- check if
>the expressions are well typed (well formed).
>Types are part of semantics not syntax, and typically doing (even partial)
>semantic checks in syntactic phase (lexer/parser) in not a good idea.
>
>rgds
>
>
Okay, thanks for that. My application is a simple scripting language
which can do simple formulas. I was thinking of having all of the
expression rules return a VariableInfo class which stored any possible
value and could perform the basic expression operations on it (add,
minus, div, mult etc) - my idea being to handle the semantic issues
within the VariableInfo class (it will check types, throw exceptions for
mismatches, perform arithmetic options if legal)
Does that sound like a basically sane approach to take?
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