Examples of com.odiago.flumebase.lang.UniversalType

com.odiago.flumebase.lang.UniversalType
A representation of an abstract type which can be unified to a specific concrete type on a per-expression basis.
This is used by functions to specify arguments and return values of variable type. These are only valid as argument and return types of FnCallExprs.

As an expression is typechecked, UniversalType instances will be compared against the actual types of arguments to the function; constraints generated by these comparisons will result in the UniversalType being replaced in the official expression by a concrete type.

UniversalType instances may carry constraints that restrict the set of concrete types to which they may be unified. Each constraint is a promotesTo relationship. e.g., adding a constraint of Type.TypeName.TYPECLASS_NUMERIC asserts that the final type this takes on must promote to TYPECLASS_NUMERIC.

Note that the equals() method operates on the alias and the constraints; if two instances of a UniversalType have the same alias and the same constraints (or no constraints at all), they will be judged "equal;" if a function has two unbound argument types that are unrelated, they should be instantiated with different aliases, such as "'a" and "'b".

 */
public class sum extends AggregateFunc<Number> {
  private UniversalType mArgType;


  public sum() {
    mArgType = new UniversalType("'a");
    mArgType.addConstraint(Type.getNullable(Type.TypeName.TYPECLASS_NUMERIC));
  }

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      Type abstractType = abstractArgTypes.get(i);
      Type actualType = mExprTypes.get(i);
      UniversalConstraintExtractor constraintExtractor = new UniversalConstraintExtractor();
      if (constraintExtractor.extractConstraint(abstractType, actualType)) {
        // Found a UniversalType. Make sure it's mapped to a list of actual constraints.
        UniversalType univType = constraintExtractor.getUniversalType();
        List<Type> actualConstraints = unifications.get(univType);
        if (null == actualConstraints) {
          actualConstraints = new ArrayList<Type>();
          unifications.put(univType, actualConstraints);
        }


        // Add the actual constraint of the expression being applied as this argument.
        actualConstraints.add(constraintExtractor.getConstraintType());
      }
    }


    // Perform unifications on all the UniversalType expressions.
    Map<Type, Type> unificationOut = new HashMap<Type, Type>();
    for (Map.Entry<UniversalType, List<Type>> unification : unifications.entrySet()) {
      UniversalType univType = unification.getKey();
      List<Type> actualConstraints = unification.getValue();
      Type out = univType.getRuntimeType(actualConstraints);
      unificationOut.put(univType, out);
    }
    
    // Finally, generate a list of concrete argument types for coercion purposes.
    for (int i = 0; i < abstractArgTypes.size(); i++ ) {

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   */
  private static class max2 extends ScalarFunc {
    private UniversalType mArgType;


    public max2() {
      mArgType = new UniversalType("'a");
    }

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