Re: Symbol Table problems in Pascal languages family

pjmlp@students.si.fct.unl.pt (Paulo Jose Matos Lopes Pinto) wrote:


> I'm trying to do a compiler for a language that derives from Pascal
>(Oberon).
> The problem is with the symbol table for types, because the types have to
>be type-name compatible and not structured compatible, that makes a bit hard
>to manipulate the builtin names,like CHAR, REAL, among others.


First, this is the only problem of name compatibility; normally, to
implement name compatibility is easier that to implement structural
compatibility.


> I decided to create symbols that relate with them, but this solution is a
>problem if the user decides to create an identifier with the same name that
>a builtin symbol.
> Some help would be welcome.


You have to put "standard names" (as 'char', 'real', 'write', 'true',
and so on) "in a block that surrounds the whole program" (I think I
quote quasi literally Wirth, User Manual&Report). So, when the program
(globally, indeed) redefines 'integer', this redefiniton is in the
program (or some subprogram) block, not in the standard block. You
have to care: when a thing is of type 'integer', as the constant 123,
you have to assign it the correct type, that of the standard block.


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