org.springframework.expression.spel.ast

Interface ValueRef

All Known Implementing Classes:

Indexer.ArrayIndexingValueRef, Indexer.CollectionIndexingValueRef, Indexer.MapIndexingValueRef, Indexer.PropertyIndexingValueRef, Indexer.StringIndexingLValue, MethodReference.MethodValueRef, PropertyOrFieldReference.AccessorLValue, ValueRef.NullValueRef, ValueRef.TypedValueHolderValueRef, VariableReference.VariableRef

public interface ValueRef

Represents a reference to a value. With a reference it is possible to get or set the value. Passing around value references rather than the values themselves can avoid incorrect duplication of operand evaluation. For example in 'list[index++]++' without a value reference for 'list[index++]' it would be necessary to evaluate list[index++] twice (once to get the value, once to determine where the value goes) and that would double increment index.

Since:

3.2

Author:

Andy Clement

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ValueRef.NullValueRef A ValueRef for the null value.
static class	ValueRef.TypedValueHolderValueRef A ValueRef holder for a single value, which cannot be set.

Method Summary

Methods

Modifier and Type	Method and Description
TypedValue	getValue() Returns the value this ValueRef points to, it should not require expression component re-evaluation.
boolean	isWritable() Indicates whether calling setValue(Object) is supported.
void	setValue(java.lang.Object newValue) Sets the value this ValueRef points to, it should not require expression component re-evaluation.

Method Detail

getValue

TypedValue getValue()

Returns the value this ValueRef points to, it should not require expression component re-evaluation.

Returns:

the value

setValue

void setValue(java.lang.Object newValue)

Sets the value this ValueRef points to, it should not require expression component re-evaluation.

Parameters:

newValue - the new value

isWritable

boolean isWritable()

Indicates whether calling setValue(Object) is supported.

Returns:

true if setValue() is supported for this value reference.