com.ekuefler.supereventbus.rebind.EventRegistrationGenerator.java Source code

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Here is the source code for com.ekuefler.supereventbus.rebind.EventRegistrationGenerator.java

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/*
 * Copyright 2013 Erik Kuefler
 *
 * Licensed 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 com.ekuefler.supereventbus.rebind;

import com.ekuefler.supereventbus.impl.EventHandlerMethod;
import com.ekuefler.supereventbus.multievent.MultiEvent;
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.TreeLogger.Type;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.NotFoundException;
import com.google.gwt.core.ext.typeinfo.TypeOracle;
import com.google.gwt.user.rebind.ClassSourceFileComposerFactory;
import com.google.gwt.user.rebind.SourceWriter;

import java.io.PrintWriter;
import java.util.LinkedList;
import java.util.List;

/**
 * Generator for {@link com.ekuefler.supereventbus.EventRegistration}. Takes care of the ugly
 * parts of creating the source writer and then delegates to {@link EventRegistrationWriter}. This
 * class is used by the GWT compiler and should not be referenced directly by users.
 *
 * @author ekuefler@gmail.com (Erik Kuefler)
 */
public class EventRegistrationGenerator extends Generator {

    @Override
    public String generate(TreeLogger logger, GeneratorContext context, String typeName)
            throws UnableToCompleteException {
        try {
            JClassType eventBinderType = context.getTypeOracle().getType(typeName);
            JClassType targetType = getTargetType(eventBinderType, context.getTypeOracle());
            SourceWriter writer = createSourceWriter(logger, context, eventBinderType, targetType);
            if (writer != null) { // Otherwise the class was already created
                new EventRegistrationWriter(logger).writeGetMethods(targetType, writer);
                writer.commit(logger);
            }
            return new StringBuilder().append(eventBinderType.getPackage().getName()).append('.')
                    .append(getSimpleGeneratedClassName(eventBinderType)).toString();
        } catch (NotFoundException e) {
            logger.log(Type.ERROR, "Error generating " + typeName, e);
            throw new UnableToCompleteException();
        }
    }

    private JClassType getTargetType(JClassType interfaceType, TypeOracle typeOracle) {
        JClassType[] superTypes = interfaceType.getImplementedInterfaces();
        return superTypes[0].isParameterized().getTypeArgs()[0];
    }

    private SourceWriter createSourceWriter(TreeLogger logger, GeneratorContext context, JClassType eventBinderType,
            JClassType targetType) {
        String simpleName = getSimpleGeneratedClassName(eventBinderType);
        String packageName = eventBinderType.getPackage().getName();
        ClassSourceFileComposerFactory composer = new ClassSourceFileComposerFactory(packageName, simpleName);

        composer.addImplementedInterface(eventBinderType.getName());
        composer.addImport(EventHandlerMethod.class.getCanonicalName());
        composer.addImport(LinkedList.class.getCanonicalName());
        composer.addImport(List.class.getCanonicalName());
        composer.addImport(MultiEvent.class.getCanonicalName());

        PrintWriter printWriter = context.tryCreate(logger, packageName, simpleName);
        return printWriter != null ? composer.createSourceWriter(context, printWriter) : null;
    }

    private String getSimpleGeneratedClassName(JClassType eventBinderType) {
        return eventBinderType.getName().replace('.', '_') + "Impl";
    }
}