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

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

All Implemented Interfaces:
  Serializable, Value

Direct Known Subclasses:
  Aggregate, AggregateVal, Args, BoundVariable, CandidatePath, Cast, Coalesce, CollectionParam, Concat, CurrentDate, Distinct, Extension, GeneralCase, GetMapValue, GetObjectId, IndexOf, Lit, MathVal, Null, NullIf, Param, SimpleCase, StringLength, SubQ, Substring, This, ToLowerCase, ToUpperCase, Trim, Type, TypeLit, UnaryMathVal, UnboundVariable

    public abstract class Val

extends Object
implements Value

An in-memory representation of a `Value`.

Author:
  Abe White
See Also:
  Serialized Form

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.
`String` | `getAlias()` Return select item alias
`ClassMetaData` | `getMetaData()` Return any associated persistent type.
`String` | `getName()`
`Path` | `getPath()`
`Value` | `getSelectAs()` Return 'this' concrete class if alias is set, otherwise null
`boolean` | `isAggregate()` Return true if this value is an aggregate.
`boolean` | `isVariable()` Return true if this value is a variable.
`boolean` | `isXPath()` Return true if this value is an XML Path.
`void` | `setAlias(String alias)` Set select item alias
`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`

### isXPath

    public boolean isXPath()

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

  Specified by:
    `isXPath` 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`

### getAlias

    public String getAlias()

  Description copied from interface: `Value`
  Return select item alias

  Specified by:
    `getAlias` in interface `Value`

### setAlias

    public void setAlias(String alias)

  Description copied from interface: `Value`
  Set select item alias

  Specified by:
    `setAlias` in interface `Value`

### getSelectAs

    public Value getSelectAs()

  Description copied from interface: `Value`
  Return 'this' concrete class if alias is set, otherwise null

  Specified by:
    `getSelectAs` in interface `Value`

### getPath

    public Path getPath()

  Specified by:
    `getPath` in interface `Value`

### getName

    public String getName()

  Specified by:
    `getName` in interface `Value`

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