org.hd.d.pg2k.webSvr.exhibit
Class SortExpr

java.lang.Object
  org.hd.d.pg2k.webSvr.exhibit.Expr
      org.hd.d.pg2k.webSvr.exhibit.SortExpr

All Implemented Interfaces:

java.io.Serializable

public final class SortExpr
extends Expr
implements java.io.Serializable

Wraps a sorter to make an expression (for a FilterBean). Sorters must be Serializable so that expressions can be persisted. They must not attempt to cache any reference, direct or indirect, to a DataSourceBean.

Sorter objects must be immutable and the sort() method must be idempotent.

TODO: do object validation on deserialisation

See Also:

Serialized Form

sorter

private final SortIF sorter

The sort we apply here; never null.

serialVersionUID

private static final long serialVersionUID

Unique Serialisation class ID generated by http://random.hd.org/.

See Also:

Constant Field Values

SortExpr

public SortExpr(Expr _upstream,
                SortIF _sorter)

Construct us with the upstream expression. If the upstream expression is null this is the first element in the expression pipeline.

eval

public Name.ExhibitFull[] eval(AllExhibitProperties aep,
                               Name.ExhibitFull[] in)

Evaluate this expression applying our sort. Given the upstream expression, compute its results and then compute ours on it.

We return a set of names, possibly empty.

The result array contains no duplicates nor nulls (providing the input is similarly well-behaved) and is never null itself.

Designed to be overridden and have super() called to collect upstream results... By itself returns all the exhibits untouched, ie is a null filter/sorter.

The result may be the input array sorted in place to avoid copying, or may be a new array possibly smaller than the input array; this may perform filtering or other operations that needs to operate on the whole (current) set of exhibits at once.

Overrides:

eval in class Expr

hashCode

public int hashCode()

Hash depends on underlying expression and this sorter.

Overrides:

hashCode in class Expr

equals

public boolean equals(java.lang.Object obj)

Equality depends on underlying expression and this sorter.

Overrides:

equals in class Expr