vaadin-framework/src/com/vaadin/terminal/gwt/rebind/WidgetMapGenerator.java

package com.vaadin.terminal.gwt.rebind;

import java.io.PrintWriter;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;

import com.google.gwt.core.ext.Generator;
import com.google.gwt.core.ext.GeneratorContext;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.core.ext.TreeLogger.Type;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.TypeOracle;
import com.google.gwt.user.rebind.ClassSourceFileComposerFactory;
import com.google.gwt.user.rebind.SourceWriter;
import com.vaadin.terminal.Paintable;
import com.vaadin.terminal.gwt.client.ui.VView;
import com.vaadin.ui.ClientWidget;

/**
 * GWT generator to build WidgetMapImpl dynamically based on
 * {@link ClientWidget} annotations available in workspace.
 * 
 */
public class WidgetMapGenerator extends Generator {

    private String packageName;
    private String className;

    @Override
    public String generate(TreeLogger logger, GeneratorContext context,
            String typeName) throws UnableToCompleteException {

        try {
            TypeOracle typeOracle = context.getTypeOracle();

            // get classType and save instance variables
            JClassType classType = typeOracle.getType(typeName);
            packageName = classType.getPackage().getName();
            className = classType.getSimpleSourceName() + "Impl";
            // Generate class source code
            generateClass(logger, context);
        } catch (Exception e) {
            logger.log(TreeLogger.ERROR, "WidgetMap creation failed", e);
        }
        // return the fully qualifed name of the class generated
        return packageName + "." + className;
    }

    /**
     * Generate source code for WidgetMapImpl
     * 
     * @param logger
     *            Logger object
     * @param context
     *            Generator context
     */
    private void generateClass(TreeLogger logger, GeneratorContext context) {
        // get print writer that receives the source code
        PrintWriter printWriter = null;
        printWriter = context.tryCreate(logger, packageName, className);
        // print writer if null, source code has ALREADY been generated, return
        if (printWriter == null) {
            return;
        }
        logger
                .log(Type.INFO,
                        "Detecting vaading components in classpath to generate WidgetMapImpl.java ...");
        Date date = new Date();

        // init composer, set class properties, create source writer
        ClassSourceFileComposerFactory composer = null;
        composer = new ClassSourceFileComposerFactory(packageName, className);
        composer.setSuperclass("com.vaadin.terminal.gwt.client.WidgetMap");
        SourceWriter sourceWriter = composer.createSourceWriter(context,
                printWriter);

        /*
         * TODO we need som sort of mechanims to exclude/include components from
         * widgetset. Properties in gwt.xml is one option. Now only possible by
         * extending this class, overriding getUsedPaintables() method and
         * redefining deferred binding rule.
         */

        Collection<Class<? extends Paintable>> paintablesHavingWidgetAnnotation = getUsedPaintables();

        TypeOracle typeOracle = context.getTypeOracle();

        for (Iterator iterator = paintablesHavingWidgetAnnotation.iterator(); iterator
                .hasNext();) {
            Class<? extends Paintable> class1 = (Class<? extends Paintable>) iterator
                    .next();

            ClientWidget annotation = class1.getAnnotation(ClientWidget.class);

            if (typeOracle.findType(annotation.value().getName()) == null) {
                // GWT widget not inherited
                logger
                        .log(
                                Type.WARN,
                                "Widget implementation for "
                                        + class1.getName()
                                        + " not available for GWT compiler. If this is not "
                                        + "intentional, check your gwt module definition file.");
                iterator.remove();
            }

        }

        // generator constructor source code
        generateImplementationDetector(sourceWriter,
                paintablesHavingWidgetAnnotation);
        generateInstantiatorMethod(sourceWriter,
                paintablesHavingWidgetAnnotation);
        // close generated class
        sourceWriter.outdent();
        sourceWriter.println("}");
        // commit generated class
        context.commit(logger, printWriter);
        logger.log(Type.INFO, "Done. ("
                + (new Date().getTime() - date.getTime()) / 1000 + "seconds)");

    }

    protected Collection<Class<? extends Paintable>> getUsedPaintables() {
        return ClassPathExplorer.getPaintablesHavingWidgetAnnotation();
    }

    private void generateInstantiatorMethod(
            SourceWriter sourceWriter,
            Collection<Class<? extends Paintable>> paintablesHavingWidgetAnnotation) {
        sourceWriter
                .println("public Paintable instantiate(Class<? extends Paintable> classType) {");
        sourceWriter.indent();

        sourceWriter
                .println("Paintable p = super.instantiate(classType); if(p!= null) return p;");

        for (Class<? extends Paintable> class1 : paintablesHavingWidgetAnnotation) {
            ClientWidget annotation = class1.getAnnotation(ClientWidget.class);
            Class<? extends com.vaadin.terminal.gwt.client.Paintable> clientClass = annotation
                    .value();
            if (clientClass == VView.class) {
                // VView's are not instantiated by widgetset
                continue;
            }
            sourceWriter.print("if (");
            sourceWriter.print(clientClass.getName());
            sourceWriter.print(".class == classType) return new ");
            sourceWriter.print(clientClass.getName());
            sourceWriter.println("();");
            sourceWriter.print(" else ");
        }
        sourceWriter
                .println("return new com.vaadin.terminal.gwt.client.ui.VUnknownComponent();");
        sourceWriter.println("}");
    }

    /**
     * 
     * @param sourceWriter
     *            Source writer to output source code
     * @param paintablesHavingWidgetAnnotation
     */
    private void generateImplementationDetector(
            SourceWriter sourceWriter,
            Collection<Class<? extends Paintable>> paintablesHavingWidgetAnnotation) {
        sourceWriter
                .println("public Class<? extends Paintable> getImplementationByServerSideClassName(String fullyQualifiedName) {");
        sourceWriter.indent();
        sourceWriter
                .println("fullyQualifiedName = fullyQualifiedName.intern();");

        for (Class<? extends Paintable> class1 : paintablesHavingWidgetAnnotation) {
            ClientWidget annotation = class1.getAnnotation(ClientWidget.class);
            Class<? extends com.vaadin.terminal.gwt.client.Paintable> clientClass = annotation
                    .value();
            sourceWriter.print("if ( fullyQualifiedName == \"");
            sourceWriter.print(class1.getName());
            sourceWriter.print("\") return ");
            sourceWriter.print(clientClass.getName());
            sourceWriter.println(".class;");
            sourceWriter.print(" else ");
        }
        sourceWriter
                .println("return com.vaadin.terminal.gwt.client.ui.VUnknownComponent.class;");
        sourceWriter.println("}");

    }

}