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

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.