package org.jboss.seam.ui.converter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.el.ValueExpression;
import javax.faces.component.StateHolder;
import javax.faces.component.UIComponent;
import javax.faces.component.UIComponentBase;
import javax.faces.component.ValueHolder;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
/**
* This class provides a chainable converter for JSF.
*
* Any JSF converter can be placed at the end of the chain. A converter that is
* placed higher up the chain should return ConverterChain.CONTINUE if
* conversion has failed. If the all converters run return
* ConverterChain.CONTINUE an unconverted value will be returned.
*
* A converter can be placed in the chain with a priority, the order in which
* converters with the same priority is run is not specified.
*
*/
public class ConverterChain implements Converter, StateHolder
{
public static final String CONTINUE = "org.jboss.seam.ui.ConverterChain.continue";
/**
* This places the converter at the end of the chain. No garuntee is made
* about the order converters which are placed on the queue with this
* priority will be run
*/
public static final int CHAIN_END = Integer.MAX_VALUE;
/**
* This places the converter at the head of the chain. No garuntee is made
* about the order converters which are placed on the queue with this
* priority will be run
*/
public static final int CHAIN_START = 0;
private List<PrioritizableConverter> converters;
private boolean dirty;
public ConverterChain()
{
// A Priority Queue would be nice but JSF has issues serializing that
converters = new ArrayList<PrioritizableConverter>();
}
/**
* Set up a ConverterChain for this component.
*
* This replaces any existing converter with a ConverterChain with the
* existing Converter at the end of the chain
*
* @param component
*/
public ConverterChain(UIComponent component)
{
this();
if (component instanceof ValueHolder)
{
ValueHolder valueHolder = (ValueHolder) component;
if (!(valueHolder.getConverter() instanceof ConverterChain))
{
ValueExpression converterValueExpression = component.getValueExpression("converter");
if (converterValueExpression != null)
{
addConverterToChain(converterValueExpression);
}
else if (valueHolder.getConverter() != null)
{
addConverterToChain(valueHolder.getConverter());
}
else
{
ValueExpression valueExpression = component.getValueExpression("value");
FacesContext facesContext = FacesContext.getCurrentInstance();
if (valueExpression != null)
{
Converter converter = facesContext.getApplication().createConverter(
valueExpression.getType(facesContext.getELContext()));
if (converter != null)
{
addConverterToChain(converter);
}
}
}
valueHolder.setConverter(this);
}
}
}
public Object getAsObject(FacesContext context, UIComponent component, String value)
throws ConverterException
{
Object output = value;
for (Converter converter : getConverters())
{
Object result = converter.getAsObject(context, component, value);
if (!CONTINUE.equals(result))
{
output = result;
break;
}
}
return output;
}
public String getAsString(FacesContext context, UIComponent component, Object value)
throws ConverterException
{
String output = value == null ? null : value.toString();
for (Converter converter : getConverters())
{
String result = converter.getAsString(context, component, value);
if (!CONTINUE.equals(result))
{
output = result;
break;
}
}
return output;
}
/**
* Add a converter to the end of the chain
*/
public boolean addConverterToChain(Converter c)
{
return addConverterToChain(c, CHAIN_END);
}
/**
* Add a converter to the end of the chain
*/
public boolean addConverterToChain(ValueExpression c)
{
return addConverterToChain(c, CHAIN_END);
}
/**
* Add a converter to the chain with a defined priority
*/
public boolean addConverterToChain(Converter c, int priority)
{
if (c != null)
{
dirty = true;
return converters.add(new PrioritizableConverter(c, priority));
}
else
{
return false;
}
}
/**
* Add a converter to the chain with a defined priority
*/
public boolean addConverterToChain(ValueExpression c, int priority)
{
if (c != null)
{
dirty = true;
return converters.add(new PrioritizableConverter(c, priority));
}
else
{
return false;
}
}
private boolean _transient;
public boolean isTransient()
{
return _transient;
}
public void restoreState(FacesContext context, Object state)
{
Object[] values = (Object[]) state;
converters = (List<PrioritizableConverter>) UIComponentBase.restoreAttachedState(context,
values[0]);
dirty = true;
}
public Object saveState(FacesContext context)
{
Object[] values = new Object[1];
values[0] = UIComponentBase.saveAttachedState(context, converters);
return values;
}
public void setTransient(boolean newTransientValue)
{
this._transient = newTransientValue;
}
private List<PrioritizableConverter> getConverters()
{
if (dirty)
{
Collections.sort(converters);
}
return converters;
}
public boolean containsConverterType(Converter converter) {
// TODO Improve this
for (Converter c : converters) {
if (c.getClass().equals(converter)) {
return true;
}
}
return false;
}
}