package com.example;

import java.util.Map;
import javax.faces.component.UIComponent;
import javax.faces.view.facelets.*;

public class ForeachTagHandler extends ComponentHandler {
    public ForeachTagHandler(ComponentConfig config) {
	super(config);
    }

    @Override
    protected MetaRuleset createMetaRuleset(Class cls) {
	MetaRuleset meta = super.createMetaRuleset(cls);
	meta.alias("class", "styleClass");
	return meta;
    }

    @Override
    public void onComponentCreated(FaceletContext ctx,
				   UIComponent c,
				   UIComponent parent) {
	TagAttribute[] allAttrs = this.tag.getAttributes().getAll();

	// we are passing thru all attributes except tag, var and value.
	String[] attrs = new String[allAttrs.length - 3];
	int j = 0;
	for (int i = 0; i < allAttrs.length; i++) {
	    String localName = allAttrs[i].getLocalName();
	    if ("tag".equals(localName) ||
		"var".equals(localName) ||
		"value".equals(localName)) {
		continue;
	    }

	    if ("class".equals(localName)) {
		attrs[j++] = "styleClass";
	    }
	    else {
		attrs[j++] = localName;
	    }
	}

	Map<String,Object> compAttrs = c.getAttributes();
	compAttrs.put("alias.attributes", attrs);
    }
}

package com.example;

import java.io.IOException;

import javax.el.ValueExpression;
import javax.faces.component.UIComponent;
import javax.faces.component.UIComponentBase;

public class UIForeach extends UIComponentBase {
    public static final String COMPONENT_TYPE = "com.example.Foreach";
    public static final String COMPONENT_FAMILY = "com.example";

    // data object
    private Object value;

    // variable name
    private String var;
    private String tag;

    public UIForeach() {
    }

    public String getFamily() {
	return COMPONENT_FAMILY;
    }

    public String getVar() {
	return this.var;
    }

    public void setVar(String var) {
	this.var = var;
    }

    public String getTag() {
	return this.tag;
    }

    public void setTag(String tag) {
	this.tag = tag;
    }

    // value is set only when the value attribute does not contain EL.
    // otherwise, setValueExpression is called with the EL value.
    public Object getValue() {
	if (this.value == null) {
	    ValueExpression vex = this.getValueExpression("value");
	    if (vex != null) {
		return vex.getValue(getFacesContext().getELContext());
	    }
	}
	return this.value;
    }

    public void setValue(Object value) {
	this.value = value;
    }

    public boolean getRendersChildren() {
	return true;
    }
}

package com.example;

import java.io.IOException;
import java.util.Map;
import java.util.Iterator;

import javax.faces.render.Renderer;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;

public class ForeachRenderer extends Renderer {
    @Override
    public void encodeBegin(FacesContext ctx, UIComponent uic) throws IOException {
	UIForeach c = (UIForeach) uic;
    	ResponseWriter w = ctx.getResponseWriter();
	w.startElement(c.getTag(), c);
	Map<String, Object> a = c.getAttributes();
	String[] attrs = (String[]) a.get("alias.attributes");
	for (int i = 0; i < attrs.length; i++) {
	    String attr = attrs[i];
	    if ("styleClass".equals(attr)) {
		w.writeAttribute("class", a.get(attr), null);
	    }
	    else {
		w.writeAttribute(attr, a.get(attr), null);
	    }
	}
    }

    @Override
    public void encodeEnd(FacesContext ctx, UIComponent uic) throws IOException {
	UIForeach c = (UIForeach) uic;
    	ResponseWriter w = ctx.getResponseWriter();
	w.endElement(c.getTag());
    }

    @Override
    public void encodeChildren(FacesContext ctx, UIComponent uic) throws IOException {
	UIForeach c = (UIForeach) uic;
	String[] values = ((String) c.getValue()).split("\\s+");
	for (int i = 0; i < values.length; i++) {
	    Map<String, Object> attrs = ctx.getExternalContext().getRequestMap();
	    attrs.put(c.getVar(), values[i]);

	    Iterator<UIComponent> it = c.getChildren().iterator();
	    while (it.hasNext()) {
		UIComponent ch = it.next();
		ch.encodeAll(ctx);
	    }
	}
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<faces-config xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_1.xsd"
    version="2.1">
    <component>
	<component-type>com.example.Foreach</component-type>
	<component-class>com.example.UIForeach</component-class>
    </component>

    <render-kit>
        <render-kit-id>HTML_BASIC</render-kit-id>
        <renderer>
            <component-family>com.example</component-family>
            <renderer-type>com.example.ForeachRenderer</renderer-type>
            <renderer-class>com.example.ForeachRenderer</renderer-class>
        </renderer>
    </render-kit>
</faces-config>

<?xml version="1.0" encoding="UTF-8"?>
<facelet-taglib
    xmlns="http://java.sun.com/xml/ns/javaee"
    version="2.0">
    <namespace>http://www.example.com/ns/facelettags</namespace>
    <tag>
	<tag-name>foreach</tag-name>
	<component>
	    <component-type>com.example.Foreach</component-type>
	    <renderer-type>com.example.ForeachRenderer</renderer-type>
	    <handler-class>com.example.ForeachTagHandler</handler-class>
	</component>
    </tag>
</facelet-taglib>