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package com.sun.faces.facelets.el;
import com.sun.faces.component.CompositeComponentStackManager;
import javax.el.ValueExpression;
import javax.el.ELContext;
import javax.faces.view.Location;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
/**
* <p>
* This specialized <code>ValueExpression</code> 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]}).
* </p>
*
* <p>
* It's important to note that these <code>ValueExpression</code>s 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.
* </p>
*
* Here's an example:
*
* <pre>
* Using Page test.xhtml
* ---------------------------------
* <ez:comp1 greeting="Hello!" />
*
*
* comp1.xhtml
* ---------------------------------
* <composite:interface>
* <composite:attribute name="greeting" type="java.lang.String" required="true" />
* </composite:interface>
* <composite:implementation>
* <ez:nesting>
* <h:outputText value="#{cc.attrs.greetings}" />
* </ez:nesting>
* </composite:implementation>
*
* nesting.xhtml
* ---------------------------------
* <composite:interface />
* <composite:implementation>
* <composite:insertChildren>
* </composite:implementation>
* </pre>
*
* <p>
* In the above example, there will be two composite components available to
* the runtime: <code>ez:comp1</code> and <code>ez:nesting</code>.
* </p>
*
* <p>
* When <h:outputText value="#{cc.attrs.greeting}" />, prior to attempting
* to evaluate the expression, the {@link Location} object will be used to
* find the composite component that '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)}.
* </p>
*/
public final class ContextualCompositeValueExpression extends ValueExpression {
private static final long serialVersionUID = -2637560875633456679L;
private ValueExpression originalVE;
private Location location;
// ---------------------------------------------------- Constructors
/* For serialization purposes */
public ContextualCompositeValueExpression() { }
public ContextualCompositeValueExpression(Location location,
ValueExpression originalVE) {
this.originalVE = originalVE;
this.location = location;
}
// ------------------------------------ Methods from ValueExpression
@Override
public Object getValue(ELContext elContext) {
FacesContext ctx = (FacesContext) elContext.getContext(FacesContext.class);
boolean pushed = pushCompositeComponent(ctx);
try {
return originalVE.getValue(elContext);
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
}
@Override
public void setValue(ELContext elContext, Object o) {
FacesContext ctx = (FacesContext) elContext.getContext(FacesContext.class);
boolean pushed = pushCompositeComponent(ctx);
try {
originalVE.setValue(elContext, o);
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
}
@Override
public boolean isReadOnly(ELContext elContext) {
FacesContext ctx = (FacesContext) elContext.getContext(FacesContext.class);
boolean pushed = pushCompositeComponent(ctx);
try {
return originalVE.isReadOnly(elContext);
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
}
@Override
public Class<?> getType(ELContext elContext) {
FacesContext ctx = (FacesContext) elContext.getContext(FacesContext.class);
boolean pushed = pushCompositeComponent(ctx);
try {
return originalVE.getType(elContext);
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
}
@Override
public Class<?> getExpectedType() {
FacesContext ctx = FacesContext.getCurrentInstance();
boolean pushed = pushCompositeComponent(ctx);
try {
return originalVE.getExpectedType();
} finally {
if (pushed) {
popCompositeComponent(ctx);
}
}
}
// --------------------------------------------- Methods from Expression
@Override
public String getExpressionString() {
return originalVE.getExpressionString();
}
@SuppressWarnings({"EqualsWhichDoesntCheckParameterClass"})
@Override
public boolean equals(Object o) {
return originalVE.equals(o);
}
@Override
public int hashCode() {
return originalVE.hashCode();
}
@Override
public boolean isLiteralText() {
return originalVE.isLiteralText();
}
@Override
public String toString() {
return originalVE.toString();
}
// ------------------------------------------------------ Public Methods
/**
* @return the {@link Location} of this <code>ValueExpression</code>
*/
public Location getLocation() {
return location;
}
// ----------------------------------------------------- Private Methods
private boolean pushCompositeComponent(FacesContext ctx) {
CompositeComponentStackManager manager =
CompositeComponentStackManager.getManager(ctx);
UIComponent cc = manager.findCompositeComponentUsingLocation(ctx, location);
return manager.push(cc);
}
private void popCompositeComponent(FacesContext ctx) {
CompositeComponentStackManager manager =
CompositeComponentStackManager.getManager(ctx);
manager.pop();
}
} // END ContextualCompositeValueExpression