Map and function types are of high utility in software specification and design, for example, maps can be used to represent configurations or caches, whilst function values can be used to enable genericity and reuse in a specification, and to support mechanisms such as callbacks or closures in an implementation. Map and function types have been incorporated into the leading programming languages, including Java, C++, Swift and Python.

The Object Constraint Language (OCL) specification notation lacks such types, and in this paper we make a proposal for a consistent extension of OCL with map and function types, and we identify modifications to OCL semantics to include these types. We also describe how map and function types are implemented using the Eclipse AgileUML toolset.

1. 1.

   Used in the ATL extension of OCL.

Authors and Affiliations

1. Department of Informatics, King’s College London, London, UK

   Kevin Lano

2. Department of Software Engineering, University of Isfahan, Isfahan, Iran

   Shekoufeh Kolahdouz-Rahimi

Corresponding author

Correspondence toKevin Lano.

Editors and Affiliations

1. Tehran Institute for Advanced Studies, Tehran, Iran

   Hossein Hojjat

2. CNR - ISTI, Pisa, Italy

   Mieke Massink

A Additional Map Type Operators

The following map operators can also be formalised in our proposed extension of OCL.

size() : Integer

This is equal to\(self{\rightarrow }keys(){\rightarrow }size()\).

includesValue(object : T) : Boolean True if theobject is an element of the map range, false otherwise:

Similarly for\({\rightarrow }includesKey()\),\({\rightarrow }excludesValue()\),\({\rightarrow }excludesKey()\).

count(object : T) : Integer The number of times theobject occurs as an element of the map range (a bag):

includesAll(c2 : Map(K,T)) : Boolean True ifc2 is a map, and the set of pairs ofself contains all those ofc2, false otherwise:

Similarly for\({\rightarrow }excludesAll()\).

isEmpty() : Boolean, notEmpty() : Boolean Defined based on\(self{\rightarrow }asSet()\).

max() : T, min() : T, sum() : T Defined as the corresponding operations on\(self{\rightarrow }values()\).

asSet() : Set(Tuple(key : K, value : T)) The set of pairs of elements in the map. Since duplicate keys are not permitted, this has the same size as\(self{\rightarrow }keys()\).

restrict(ks : Set(K)) : Map(K,T) Domain restriction. The map restricted to the keys inks. Its elements are the pairs ofself whose key is inks:

Range restriction is provided via the\({\rightarrow }select\) operator.

-(m: Map(K,T)) : Map(K,T) Map subtraction: the elements ofself that are not inm.

union(m : Map(K,T)) : Map(K,T) Map override, the operation\(self \oplus m\) or\(self~{{<}{+}}~m\) in mathematical notation. This consists of the pairs ofself which do not conflict with pairs ofm, together with all pairs ofm:

This is the same asputAll in EOL [9]. Unlike set union, it is not commutative.

intersection(m : Map(K,T)) : Map(K,T) The pairs ofself which are also inm:

This is associative and commutative.

including(k : K, v : T) : Map(K,T) The pairs ofself, with the additional/overriding mapping ofk tov:

We also use the abbreviated notation\(m[k] = v\) for\(m = m{\text{@ }pre}{\rightarrow }including(k,v)\).

excluding(k : K, v : T) : Map(K,T) The pairs ofself, with any mapping ofk tov removed:

any Defined as

Likewise forforAll,exists,one.

select The map formed by restricting to range elements which satisfy theselect condition:

Similarly forreject.

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