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4   Checks

Responsible: Thomas Richter, Karsten Stahl, Martin Steffen, all others too

Only syntactically correct systems can be meaningfully processed, in our case simulated. The task of this package is to check syntactical consistency. The task comprises the definition of what syntactical correctness means, i.e., what is guaranteed/checked by this group upon which the others can rely on.


With the gui. The gui has to take care that the packages for graph-placement, simulation, model-checking, code-generation ...are handed over only checked syntax. What needs not to be checked are ``graphical lapses'', e.g., whether the nodes are placed one over the other or similar things.


The checker assures well-typedness of expressions. The languages is rather simple and the abstract syntax of Section A only features integers and booleans and no scopes. We assume that the language is well-typed. The types of the operators is shown in Table 1.

operator/constant type(s)
true,false Bool
0,1,... Int
+,*,/ Int × Int ® Int
- Int × Int ® Int, Int®Int
<,>,£,³ Int ×Int ® Bool
=, ¹ Int×Int ® Bool, Bool×Bool®Bool
¬ Bool® Bool

Table 1: Types

Besides (and prior to) type-checking, the checker detects also various situations, when the programs is considered to be ill-formed. The checker guarantees, that Note that test of non-nullness is not done for parts other than mentioned (for instance sap's etc.)

last generated July 10, 2002 (©Public License)
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