Package org.springframework.expression.spel.ast

Interface ValueRef

All Known Implementing Classes:
ValueRef.NullValueRef, ValueRef.TypedValueHolderValueRef
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
    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
    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(Object newValue)
    Sets the value this ValueRef points to, it should not require expression component re-evaluation.

  • Method Details

    • getValue

      TypedValue getValue()
      Returns the value this ValueRef points to, it should not require expression component re-evaluation.
      Returns:
      the value

    • setValue

      void setValue(@Nullable 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.