Package opendap.servers

Class AbstractClause

  • All Implemented Interfaces:
    Clause
    Direct Known Subclasses:
    BoolFunctionClause, BTFunctionClause, DereferenceClause, RelOpClause, ValueClause
    public abstract class AbstractClause
extends Object
implements Clause
    Provides default implementations for the Clause interface methods. This eliminates redundant code and provides a starting point for new implementations of Clause.

    Note that every Clause object is expected to implement either SubClause or TopLevelClause. No default implementations are provided for the methods of these subinterfaces

    Also note that it is not necessary to use this class to create your own implementations, it's just a convenience.

    The class has no abstract methods, but is declared abstract because it should not be directly instantiated.

    • Field Detail

      • constant

        protected boolean constant
        Value to be returned by isConstant(). Should not change for the lifetime of the object.

      • defined

        protected boolean defined
        Value to be returned by isDefined(). May change during the lifetime of the object.

      • children

        protected List children
        A list of SubClause objects representing the sub-clauses of this clause. Use caution when modifying this list other than at the point of creation, since methods such as evaluate() depend on it.

    • Constructor Detail

      • AbstractClause

        public AbstractClause()

    • Method Detail

      • getChildren

        public List getChildren()
        Description copied from interface: Clause
        Returns an ordered list of this clause's sub-clauses. If the clause has no sub-clauses, an empty list will be returned.
        Specified by:
        getChildren in interface Clause

      • isConstant

        public boolean isConstant()
        Description copied from interface: Clause
        A clause is considered "constant" iff it and its subclauses do not refer to data values from the dataset being constrained. A constant clause is defined as soon as it is created, and is guaranteed not to change its value during its lifetime.
        Specified by:
        isConstant in interface Clause

      • isDefined

        public boolean isDefined()
        Description copied from interface: Clause
        Returns whether or not the clause has a defined value. Non-constant clauses do not have a defined value until they are evaluated for the first time. Methods for evaluating are found in the TopLevelClause and SubClause interfaces.
        Specified by:
        isDefined in interface Clause