CompositeTagLibrary.java

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package com.sun.faces.facelets.tag;

import com.sun.faces.facelets.compiler.CompilationMessageHolder;
import com.sun.faces.facelets.tag.jsf.CompositeComponentTagLibrary;
import com.sun.faces.facelets.tag.jsf.FacesComponentTagLibrary;
import com.sun.faces.facelets.tag.jsf.LazyTagLibrary;
import com.sun.faces.util.Util;

import javax.faces.FacesException;
import javax.faces.application.FacesMessage;
import javax.faces.application.ProjectStage;
import javax.faces.context.FacesContext;
import javax.faces.view.facelets.Tag;
import javax.faces.view.facelets.TagConfig;
import javax.faces.view.facelets.TagHandler;
import java.lang.reflect.Method;
import java.util.List;

/**
 * A TagLibrary that is composed of 1 or more TagLibrary children. Uses the
 * chain of responsibility pattern to stop searching as soon as one of the
 * children handles the requested method.
 * 
 * @author Jacob Hookom
 * @version $Id$
 */
public final class CompositeTagLibrary implements TagLibrary {

    private TagLibrary[] libraries;
    private CompilationMessageHolder messageHolder;

    public CompositeTagLibrary(TagLibrary[] libraries, CompilationMessageHolder unit) {
        Util.notNull("libraries", libraries);
        this.libraries = libraries;
        this.messageHolder = unit;
    }

    public CompositeTagLibrary(TagLibrary[] libraries) {
        this(libraries, null);
    }
    
    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.tag.TagLibrary#containsNamespace(java.lang.String)
     */
    @Override
    public boolean containsNamespace(String ns, Tag t) {
        boolean result = true;
        for (int i = 0; i < this.libraries.length; i++) {
            if (this.libraries[i].containsNamespace(ns, null)) {
                return true;
            }
        }
        // PENDING: this is a terribly inefficient impl.  Needs refactoring.
        LazyTagLibrary lazyLibraries [] = new LazyTagLibrary[2];
        lazyLibraries[0] = new CompositeComponentTagLibrary(ns);
        lazyLibraries[1] = new FacesComponentTagLibrary(ns);
        LazyTagLibrary toTest = null;
        for (int i = 0; i < lazyLibraries.length; i++) {
            if (lazyLibraries[i].tagLibraryForNSExists(ns)) {
                toTest = lazyLibraries[i];
                break;
            }
        }
        if (null != toTest) {
            TagLibrary [] librariesPlusOne = new TagLibrary[libraries.length+1];
            System.arraycopy(this.libraries, 0, librariesPlusOne, 
                    0, libraries.length);
            librariesPlusOne[libraries.length] = toTest;
            for (int i = 0; i < this.libraries.length; i++) {
                libraries[i] = null;
            }
            libraries = librariesPlusOne;
            return true;
        }
        else {
            FacesContext context = FacesContext.getCurrentInstance();
            if (context.isProjectStage(ProjectStage.Development)) {
                if (null != t &&
                    !ns.equals("http://www.w3.org/1999/xhtml")) {
                    // messageHolder will only be null in the case of the private 
                    // EMPTY_LIBRARY class variable of the Compiler class.
                    // This code will never be called on that CompositeTagLibrary
                    // instance.
                    assert(null != this.messageHolder);
                    String prefix = getPrefixFromTag(t);
                    if (null != prefix) {
                        List<FacesMessage> prefixMessages = this.messageHolder.getNamespacePrefixMessages(context, prefix);
                        prefixMessages.add(new FacesMessage(FacesMessage.SEVERITY_WARN,
                                "Warning: This page calls for XML namespace " + ns +
                                " declared with prefix " + prefix + 
                                " but no taglibrary exists for that namespace.", ""));
                    }
                }
            }
        }
        return false;
    }
    
    private String getPrefixFromTag(Tag t) {
        String result = t.getQName();
        if (null != result) {
            int i;
            if (-1 != (i = result.indexOf(":"))) {
                result = result.substring(0, i);
            }
        }
        return result;
    }
    
    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.tag.TagLibrary#containsTagHandler(java.lang.String,
     *      java.lang.String)
     */
    @Override
    public boolean containsTagHandler(String ns, String localName) {
        for (int i = 0; i < this.libraries.length; i++) {
            if (this.libraries[i].containsTagHandler(ns, localName)) {
                return true;
            }
        }
        return false;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.tag.TagLibrary#createTagHandler(java.lang.String,
     *      java.lang.String, com.sun.facelets.tag.TagConfig)
     */
    @Override
    public TagHandler createTagHandler(String ns, String localName,
            TagConfig tag) throws FacesException {
        for (int i = 0; i < this.libraries.length; i++) {
            if (this.libraries[i].containsTagHandler(ns, localName)) {
                return this.libraries[i].createTagHandler(ns, localName, tag);
            }
        }
        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.tag.TagLibrary#containsFunction(java.lang.String,
     *      java.lang.String)
     */
    @Override
    public boolean containsFunction(String ns, String name) {
        for (int i = 0; i < this.libraries.length; i++) {
            if (this.libraries[i].containsFunction(ns, name)) {
                return true;
            }
        }
        return false;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.sun.facelets.tag.TagLibrary#createFunction(java.lang.String,
     *      java.lang.String)
     */
    @Override
    public Method createFunction(String ns, String name) {
        for (int i = 0; i < this.libraries.length; i++) {
            if (this.libraries[i].containsFunction(ns, name)) {
                return this.libraries[i].createFunction(ns, name);
            }
        }
        return null;
    }
}