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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF1.2 features. A JSF1.2 implementation is required to use this version of the Tomahawk library.
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.myfaces.custom.buffer;

import javax.el.ValueExpression;
import javax.faces.component.UIComponentBase;
import javax.faces.context.FacesContext;

import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFComponent;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFJspProperties;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFJspProperty;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFProperty;

/**
 * A component that renders its child components into an in-memory buffer rather than
 * render them directly to the response stream.
 * 
 * Property "into" is an EL expression that specifies where to store a String holding
 * the results of rendering all the children of this component; this is assigned to
 * after rendering of this component (and its children) is complete.
 * 
 * 
 * Typically, an h:output tag is then used later in the same page to output the buffer
 * contents.
 * 
 * 
 * This can be useful with JSF1.1/JSP2.0 to work around the well-known problem where
 * on first render of a page, a component "A" cannot reference a component "B" which is
 * defined later in the page because it has not yet been created. A solution is to define
 * "B" before "A", but wrapped in a Buffer component. Component A can then be rendered
 * and successfully reference "B" because it now exists. And later in the page, the buffer
 * contents can then be output, preserving the original layout.
 * 
 * 
 * This can also be useful when rendering the same data block multiple times within a page.
 * For example, a datatable can be rendered with a datascroller both before and after it;
 * first render the table into a buffer B1, then render the datascroller into a buffer B2,
 * then output buffers B2,B1,B2.
 * 
 * 
 * @since 1.1.7
 * @author Sylvain Vieujot (latest modification by $Author: lu4242 $)
 * @version $Revision: 691871 $ $Date: 2008-09-03 23:32:08 -0500 (Wed, 03 Sep 2008) $
 */
@JSFComponent(
        name = "t:buffer",
        clazz = "org.apache.myfaces.custom.buffer.Buffer",
        tagClass = "org.apache.myfaces.custom.buffer.BufferTag")
@JSFJspProperties(properties={
        @JSFJspProperty(
                name = "rendered",
                returnType = "boolean", 
                tagExcluded = true),
        @JSFJspProperty(
                name = "binding",
                returnType = "java.lang.String",
                tagExcluded = true),
        @JSFJspProperty(
                name = "id",
                returnType = "java.lang.String",
                tagExcluded = true)
                })
public abstract class AbstractBuffer extends UIComponentBase{

    public static final String COMPONENT_TYPE = "org.apache.myfaces.Buffer";
    public static final String COMPONENT_FAMILY = "javax.faces.Data";
    private static final String DEFAULT_RENDERER_TYPE = "org.apache.myfaces.Buffer";

    protected abstract String getLocalInto();
    
    public abstract void setInto(String into);

    void fill(String content, FacesContext facesContext){
        ValueExpression intoVB;

        if (getLocalInto() == null) {
            intoVB = getValueExpression("into");
            setInto(intoVB.getExpressionString());
        } else {
            intoVB = facesContext.getApplication().
            getExpressionFactory().createValueExpression(
                    facesContext.getELContext(), getLocalInto(), Object.class );
        }

        intoVB.setValue(facesContext.getELContext(), content);
    }
    
    /**
     * An EL expression that specifies where to store a String holding 
     * the results of rendering all the children of this component; 
     * this is assigned to after rendering of this component (and its 
     * children) is complete.
     * 
     */
    @JSFProperty(
            required = true,
            localMethod = true)
    protected abstract String getInto(); 

}