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## org.apache.openjpa.kernel.exps
Class Val

    java.lang.Object
      org.apache.openjpa.kernel.exps.Val

All Implemented Interfaces:
  Value

    public abstract class Val

extends Object
implements Value

An in-memory representation of a `Value`.

Author:
  Abe White

Constructor Summary
`Val()`

Method Summary
`void` | `acceptVisit(ExpressionVisitor visitor)` Accept a visit from a tree visitor.
`protected Collection` | `eval(Collection candidates, Object orig, StoreContext ctx, Object[] params)` Return a list of values resulting from evaluating each given candidate.
`protected abstract Object` | `eval(Object candidate, Object orig, StoreContext ctx, Object[] params)` Return this value for the given candidate.
`Object` | `evaluate(Collection candidates, Object orig, StoreContext ctx, Object[] params)` Return this value as an aggregate projection on the given group of candidates.
`Object` | `evaluate(Object candidate, Object orig, StoreContext ctx, Object[] params)` Return this value as a projection on the given candidate.
`ClassMetaData` | `getMetaData()` Return any associated persistent type.
`boolean` | `isAggregate()` Return true if this value is an aggregate.
`boolean` | `isVariable()` Return true if this value is a variable.
`void` | `setMetaData(ClassMetaData meta)` Associate a persistent type with this value.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface org.apache.openjpa.kernel.exps.Value
`getType, setImplicitType`

Constructor Detail

### Val

    public Val()

Method Detail

### evaluate

    public final Object evaluate(Object candidate,
                                 Object orig,
                                 StoreContext ctx,
                                 Object[] params)

  Return this value as a projection on the given candidate.

### evaluate

    public final Object evaluate(Collection candidates,
                                 Object orig,
                                 StoreContext ctx,
                                 Object[] params)

  Return this value as an aggregate projection on the given group of candidates.

### eval

    protected abstract Object eval(Object candidate,
                                   Object orig,
                                   StoreContext ctx,
                                   Object[] params)

  Return this value for the given candidate.

### eval

    protected Collection eval(Collection candidates,
                              Object orig,
                              StoreContext ctx,
                              Object[] params)

  Return a list of values resulting from evaluating each given candidate. By default, this implementation invokes `#eval(Object,Object,StoreContext,Map)` for each instance and packs the return value into a new list. Aggregates should override.

### getMetaData

    public ClassMetaData getMetaData()

  Description copied from interface: `Value`
  Return any associated persistent type.

  Specified by:
    `getMetaData` in interface `Value`

### setMetaData

    public void setMetaData(ClassMetaData meta)

  Description copied from interface: `Value`
  Associate a persistent type with this value.

  Specified by:
    `setMetaData` in interface `Value`

### isVariable

    public boolean isVariable()

  Description copied from interface: `Value`
  Return true if this value is a variable.

  Specified by:
    `isVariable` in interface `Value`

### isAggregate

    public boolean isAggregate()

  Description copied from interface: `Value`
  Return true if this value is an aggregate.

  Specified by:
    `isAggregate` in interface `Value`

### acceptVisit

    public void acceptVisit(ExpressionVisitor visitor)

  Description copied from interface: `Value`
  Accept a visit from a tree visitor.

  Specified by:
    `acceptVisit` in interface `Value`

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Copyright © 2006 Apache Software Foundation. All Rights Reserved.