com.sun.faces.facelets.el.ContextualCompositeMethodExpression Maven / Gradle / Ivy
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package com.sun.faces.facelets.el;
import com.sun.faces.component.CompositeComponentStackManager;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.el.MethodInfo;
import javax.el.ELContext;
import javax.el.ELException;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.view.Location;
/**
*
* This specialized MethodExpression enables the evaluation of
* composite component expressions. Instances of this expression will be created
* when {@link com.sun.faces.facelets.tag.TagAttributeImpl#getValueExpression(javax.faces.view.facelets.FaceletContext, Class)}
* is invoked and the expression represents a composite component expression (i.e. #{cc.[properties]}).
*
*
*
* It's important to note that these MethodExpressions are context
* sensitive in that they leverage the location in which they were referenced
* in order to push the proper composite component to the evaluation context
* prior to evaluating the expression itself.
*
*
* Here's an example:
*
*
* Using Page test.xhtml
* ---------------------------------
* <ez:comp1 do="#{bean.action}" />
*
*
* comp1.xhtml
* ---------------------------------
* <composite:interface>
* <composite:attribute name="do" method-signature="String f()" required="true" />
* </composite:interface>
* <composite:implementation>
* <ez:nesting>
* <h:commandButton value="Click Me!" action="#{cc.attrs.do} />
* </ez:nesting>
* </composite:implementation>
*
* nesting.xhtml
* ---------------------------------
* <composite:interface />
* <composite:implementation>
* <composite:insertChildren>
* </composite:implementation>
*
*
* When commandButton is clicked, the ContextualCompositeMethodExpression
* first is looked up by {@link com.sun.faces.facelets.tag.TagAttributeImpl.AttributeLookupMethodExpression}
* which results an instance of ContextualCompositeMethodExpression.
* When this ContextualCompositeMethodExpression is invoked, the {@link javax.faces.view.Location}
* object necessary to find the proper composite component will be derived from
* source ValueExpression provided at construction time. Using the
* derived {@link javax.faces.view.Location}, we can find the composite component
* that matches 'owns' the template in which the expression was defined in by
* comparing the path of the Location with the name and library of the {@link javax.faces.application.Resource}
* instance associated with each composite component. If a matching composite
* component is found, it will be made available to the EL by calling {@link CompositeComponentStackManager#push(javax.faces.component.UIComponent)}.
*
*/
public class ContextualCompositeMethodExpression extends MethodExpression {
private final MethodExpression delegate;
private final ValueExpression source;
private final Location location;
private final transient UIComponent cc;
// -------------------------------------------------------- Constructors
public ContextualCompositeMethodExpression(ValueExpression source,
MethodExpression delegate) {
this.delegate = delegate;
this.source = source;
this.location = null;
FacesContext ctx = FacesContext.getCurrentInstance();
this.cc = UIComponent.getCurrentCompositeComponent(ctx);
}
public ContextualCompositeMethodExpression(Location location,
MethodExpression delegate) {
this.delegate = delegate;
this.location = location;
this.source = null;
FacesContext ctx = FacesContext.getCurrentInstance();
this.cc = UIComponent.getCurrentCompositeComponent(ctx);
}
// ------------------------------------------- Methods from MethodExpression
public MethodInfo getMethodInfo(ELContext elContext) {
return delegate.getMethodInfo(elContext);
}
public Object invoke(ELContext elContext, Object[] objects) {
FacesContext ctx = (FacesContext) elContext.getContext(FacesContext.class);
try {
boolean pushed = pushCompositeComponent(ctx);
try {
return delegate.invoke(elContext, objects);
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
} catch (ELException ele) {
if (source != null) {
// special handling when an ELException handling. This is necessary
// when there are multiple levels of composite component nesting.
// When this happens, we need to evaluate the source expression
// to find and invoke the MethodExpression at the next highest
// nesting level. Is there a cleaner way to detect this case?
Object fallback = source.getValue(elContext);
if (fallback != null && fallback instanceof MethodExpression) {
return ((MethodExpression) fallback).invoke(elContext, objects);
} else {
throw ele;
}
}
throw ele;
}
}
// ------------------------------------------------- Methods from Expression
public String getExpressionString() {
return delegate.getExpressionString();
}
@SuppressWarnings({"EqualsWhichDoesntCheckParameterClass"})
public boolean equals(Object o) {
return delegate.equals(o);
}
public int hashCode() {
return delegate.hashCode();
}
public boolean isLiteralText() {
return delegate.isLiteralText();
}
// ----------------------------------------------------- Private Methods
private boolean pushCompositeComponent(FacesContext ctx) {
CompositeComponentStackManager manager =
CompositeComponentStackManager.getManager(ctx);
UIComponent foundCc = null;
if (location != null) {
foundCc = manager.findCompositeComponentUsingLocation(ctx, location);
} else {
// We need to obtain the Location of the source expression in order
// to find the composite component that needs to be available within
// the evaluation stack.
if (source instanceof TagValueExpression) {
ValueExpression orig = ((TagValueExpression) source).getWrapped();
if (orig instanceof ContextualCompositeValueExpression) {
foundCc = manager.findCompositeComponentUsingLocation(ctx, ((ContextualCompositeValueExpression) orig).getLocation());
}
}
}
if (null == foundCc) {
foundCc = this.cc;
}
return manager.push(foundCc);
}
private void popCompositeComponent(FacesContext ctx) {
CompositeComponentStackManager manager =
CompositeComponentStackManager.getManager(ctx);
manager.pop();
}
} // END ContextualCompositeMethodExpression