uk.ac.ed.epcc.safe.accounting.expr

Class SelectPropExpression<T>

java.lang.Object

uk.ac.ed.epcc.safe.accounting.expr.SelectPropExpression<T>

Type Parameters:

T -

All Implemented Interfaces:

java.lang.Iterable<PropExpression<T>>, PropExpression<T>, uk.ac.ed.epcc.webapp.Targetted<T>

public class SelectPropExpression<T>
extends java.lang.Object
implements PropExpression<T>, java.lang.Iterable<PropExpression<T>>

An expression that selects a result from a list of expressions. If the allowAny() method returns true then all expressions are equivalent and a later expression in the list can be used if necessary. Otherwise each expression must be evaluated in turn until one returns a non-null value. In this case it is not acceptable to skip an expression that might be evaluated

Author:

spb

Constructor Summary

Constructors

Constructor and Description
SelectPropExpression(boolean use_any, java.lang.Class<? super T> target, PropExpression<T>[] alts)
SelectPropExpression(java.lang.Class<? super T> target, PropExpression<T>[] alts)

Method Summary

Methods

Modifier and Type	Method and Description
<R> R	accept(BasePropExpressionVisitor<R> vis) Visitor pattern.
boolean	allowAny()
SelectPropExpression<T>	copy() Generate an equivalent (and where possible immutable) copy of this expression.
boolean	equals(java.lang.Object obj)
PropExpression<T>	get(int i)
java.lang.Class<? super T>	getTarget()
int	hashCode()
java.util.Iterator<PropExpression<T>>	iterator()
int	length()
static SelectPropExpression	makeSelect(PropExpression[] e) Utility class to generate SelectPropExpression with a sensible target type.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SelectPropExpression

public SelectPropExpression(java.lang.Class<? super T> target,
                    PropExpression<T>[] alts)

SelectPropExpression

public SelectPropExpression(boolean use_any,
                    java.lang.Class<? super T> target,
                    PropExpression<T>[] alts)

Method Detail

allowAny

public boolean allowAny()

length

public int length()

get

public PropExpression<T> get(int i)

accept

public <R> R accept(BasePropExpressionVisitor<R> vis)
         throws java.lang.Exception

Description copied from interface: PropExpression

Visitor pattern. Have the BasePropExpressionVisitor visit this expression

Specified by:

accept in interface PropExpression<T>

Throws:

java.lang.Exception

Type Parameters:

R - type of return

Parameters:

vis - visitor

Returns:

result of type R

getTarget

public java.lang.Class<? super T> getTarget()

Specified by:

getTarget in interface uk.ac.ed.epcc.webapp.Targetted<T>

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

makeSelect

public static SelectPropExpression makeSelect(PropExpression[] e)

Utility class to generate SelectPropExpression with a sensible target type.

Parameters:

e -

Returns:

SelectPropExpression

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

copy

public SelectPropExpression<T> copy()

Description copied from interface: PropExpression

Generate an equivalent (and where possible immutable) copy of this expression. Most implementing types should themselves be immutable, calling copy on their arguments and returning a self-reference for copy. In this case the return type of the function should be narrowed to the implemeting sub-type.

Specified by:

copy in interface PropExpression<T>

Returns:

PropExpression

iterator

public java.util.Iterator<PropExpression<T>> iterator()

Specified by:

iterator in interface java.lang.Iterable<PropExpression<T>>