Translating Designators
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Here is the specification for translating designators:
282 'action' Designator(Desig: DESIG -> Type: TYPE)
283 'rule' Designator(id(Ident, Pos) -> T) :
284 Apply(Ident, Pos -> Obj)
285 Access(Obj, Pos -> T)
286 'rule' Designator(subscr(Array, Index, Pos) -> T) :
287 Designator(Array -> TArray)
288 Expression(Index -> TIndex)
289 CheckArrayType(TArray, Pos -> Lwb, Upb, T)
290 TypeSize(T -> Size)
291 CheckInt(TIndex, Pos)
292 CHK(Lwb, Upb)
293 LDC(1, Lwb)
294 SUB
295 IXA(Size)
296 'action' Access(Obj: OBJ, Pos: POS -> Type: TYPE)
297 'rule' Access(object(varobj(Offset, Type), Level, Hidden), Pos
298 -> Type) :
299 GetCurrentNesting(-> CurLev)
300 LDA(CurLev-Level, Offset)
301 'rule' Access(object(varparamobj(Offset,Type), Level, Hidden),
302 Pos -> Type) :
303 GetCurrentNesting(-> CurLev)
304 LDA(CurLev-Level, Offset)
305 LDI
306 'rule' Access(object(valueparamobj(Offset,Type),Level,Hidden),
307 Pos -> Type) :
308 GetCurrentNesting(-> CurLev)
309 LDA(CurLev-Level, Offset)
310 'rule' Access(object(procobj(_,_),_,_), Pos -> none) :
311 Error("procedure not allowed here", Pos)
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Designator
Designator(Desig -> Type) generates code for the designator Desig (a construct yielding an address) and computes its type Type.
If the designator is a simple identifier, we look up its definition and use Access to determine the code and type.
Access
Access(Obj, Pos -> Type) generates the code to access the object Obj and return its type. By way of an example, consider the rule that handles variables:
'rule' Access(object(varobj(Offset, Type), Level, Hidden), Pos
-> Type) :
GetCurrentNesting(-> CurLev)
LDA(CurLev-Level, Offset)
The object has the offset Offset and the type Type ;
it was declared on nesting level Level.
This results in an instruction
LDA CurLev-Level, Offset
where CurLevel is the nesting level of the location
where the object is used.
The representation of objects is discussed next.