org.codehaus.plexus.interpolation
Class AbstractFunctionValueSourceWrapper

java.lang.Object
  extended by org.codehaus.plexus.interpolation.AbstractFunctionValueSourceWrapper
All Implemented Interfaces:
ValueSource

public abstract class AbstractFunctionValueSourceWrapper
extends java.lang.Object
implements ValueSource

ValueSource abstract implementation that wraps another value source. When an expression is resolved, this wrapped source is first used to retrieve the expression's actual value; then, the last expression processed by this source is retrieved, and the two are passed into the abstract method executeFunction(String, Object) together. The result of this is returned as the resolved value for the second expression.
This allows the first expression to be a function name that modifies the value of the second expression, which is resolved from the wrapped value source.

Version:
$Id: AbstractFunctionValueSourceWrapper.java 7529 2008-07-20 20:24:21Z olamy $

Constructor Summary
protected AbstractFunctionValueSourceWrapper(ValueSource valueSource)
          Construct a new function value source instance, using the supplied ValueSource to retrieve the input values for the function(s) this class implements.
 
Method Summary
protected abstract  java.lang.Object executeFunction(java.lang.String expression, java.lang.Object value)
          Execute the function referenced in the last-processed expression using the value resolved from the current expression (using the embedded ValueSource).
 java.lang.Object getValue(java.lang.String expression)
           Resolve the current expression using the embedded ValueSource Retrieve the last expression processed by this value source Pass the last expression (which should be the function name), along with the value for the current expression, into the executeFunction(..) method Return the result of the executeFunction(..) as the resolved value for the current expression.
protected  ValueSource getValueSource()
          Retrieve the embedded value source.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.codehaus.plexus.interpolation.ValueSource
clearFeedback, getFeedback
 

Constructor Detail

AbstractFunctionValueSourceWrapper

protected AbstractFunctionValueSourceWrapper(ValueSource valueSource)
Construct a new function value source instance, using the supplied ValueSource to retrieve the input values for the function(s) this class implements.

Parameters:
valueSource - The value source to wrap
Method Detail

getValue

public java.lang.Object getValue(java.lang.String expression)
  1. Resolve the current expression using the embedded ValueSource
  2. Retrieve the last expression processed by this value source
  3. Pass the last expression (which should be the function name), along with the value for the current expression, into the executeFunction(..) method
  4. Return the result of the executeFunction(..) as the resolved value for the current expression.

Specified by:
getValue in interface ValueSource
Returns:
the value related to the expression, or null if not found.

getValueSource

protected ValueSource getValueSource()
Retrieve the embedded value source.


executeFunction

protected abstract java.lang.Object executeFunction(java.lang.String expression,
                                                    java.lang.Object value)
Execute the function referenced in the last-processed expression using the value resolved from the current expression (using the embedded ValueSource).

Parameters:
expression - The last expression to be processed by this value source.
value - The value for the current expression, resolved by the embedded ValueSource
Returns:
The result of modifying the current expression's value using the function named by the last expression.


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