CIF 3

Bounded lists and arraysΒΆ

CIF can only represent lists (type list) with at most 2,147,483,647 (= 231 - 1) elements. Using lists with more elements results in the CIF model being invalid, and leads to runtime errors. For instance, consider the following CIF specification:

automaton a:
  disc list int x;

  location:
    initial;
    edge do x := x + [1];
end

Each time the edge is taken, another element is added to list x. As soon as an attempt is made to add the 2,147,483,648th element, a runtime error occurs.

It is possible to explicitly restrict the number of elements that may be contained in a list:

disc list[3..7] int y;      // List with at least 3 and at most 7 elements.

Variable y can only have lists as its value that have at least 3 and at most 7 elements. Assigning a list with any other number of elements is not allowed. Lists with size restrictions are called bounded lists. They can also be called size restricted lists or ranged lists. The default value for y is [0, 0, 0]. That is, the default value has the least amount of elements that is allowed by the bounded list, and the default value (0) of the element type (int).

Lists with a fixed length are called arrays:

disc list[5..5] int a;      // List with at least 5 and at most 5 elements.
disc list[5]    int b;      // Shorter but equivalent array notation.

By giving a bounded list the same lower and upper bound, the bounded list has a fixed number of elements, and can be called an array. Arrays also have a shorter and more convenient notation, where the number of elements is only given once. Both notations for arrays are equivalent.

Both bounded lists and arrays support the same operations as regular lists, and can be modified (assigned) the same way as regular lists, as long as their size restrictions are not violated.