com.google.speedtracer.generators.BuildInfoGenerator.java Source code

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Here is the source code for com.google.speedtracer.generators.BuildInfoGenerator.java

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/*
 * Copyright 2009 Google Inc.
 * 
 * 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.google.speedtracer.generators;

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.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.JMethod;
import com.google.gwt.core.ext.typeinfo.JType;
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 com.google.speedtracer.client.BuildInfo;

import java.io.PrintWriter;

/**
 * A generator that uses system properties to populate a client instance of
 * {@link BuildInfo}.
 */
public class BuildInfoGenerator extends Generator {

    private static final String REVISION_PROPERTY_NAME = "speedtracer.revision";

    private static final String BUILD_INFO_QN = BuildInfo.class.getCanonicalName();

    private static final String REVISION_METHOD_NAME = "getBuildRevision";

    private static final String TIME_METHOD_NAME = "getBuildTime";

    private static int getBuildRevision() {
        final String revision = System.getProperty(REVISION_PROPERTY_NAME);
        if (revision == null) {
            return 0;
        }
        return Integer.parseInt(revision);
    }

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

        if (!typeName.equals(BUILD_INFO_QN)) {
            logger.log(TreeLogger.ERROR, "The type passed to GWT.create() must be " + BUILD_INFO_QN);
            throw new UnableToCompleteException();
        }

        final TypeOracle typeOracle = context.getTypeOracle();
        JClassType typeClass;
        try {
            typeClass = typeOracle.getType(typeName);
        } catch (NotFoundException e) {
            logger.log(TreeLogger.ERROR, "Unable to find type: " + typeName);
            throw new UnableToCompleteException();
        }

        JMethod revisionMethod;
        try {
            revisionMethod = typeClass.getMethod("getBuildRevision", new JType[0]);
        } catch (NotFoundException e) {
            logger.log(TreeLogger.ERROR, typeName + " does not have a method: int " + REVISION_METHOD_NAME + "()");
            throw new UnableToCompleteException();
        }

        JMethod timeMethod;
        try {
            timeMethod = typeClass.getMethod(TIME_METHOD_NAME, new JType[0]);
        } catch (NotFoundException e) {
            logger.log(TreeLogger.ERROR, typeName + " does not have a method: int " + TIME_METHOD_NAME + "()");
            throw new UnableToCompleteException();
        }

        return emitImplClass(logger, context, typeClass, revisionMethod, timeMethod);
    }

    private String emitImplClass(TreeLogger logger, GeneratorContext context, JClassType typeClass,
            JMethod revisionMethod, JMethod timeMethod) {
        final int revision = getBuildRevision();
        final String subclassName = typeClass.getSimpleSourceName() + "_r" + revision;
        final String packageName = typeClass.getPackage().getName();
        final ClassSourceFileComposerFactory f = new ClassSourceFileComposerFactory(packageName, subclassName);
        f.addImplementedInterface(typeClass.getQualifiedSourceName());
        final PrintWriter pw = context.tryCreate(logger, packageName, subclassName);
        if (pw != null) {
            final SourceWriter sw = f.createSourceWriter(context, pw);

            sw.print(revisionMethod.getReadableDeclaration(false, true, true, true, true));
            sw.println("{ return " + revision + "; }");

            sw.print(timeMethod.getReadableDeclaration(false, true, true, true, true));
            sw.println("{ return new java.util.Date(" + System.currentTimeMillis() + "L); }");
            sw.commit(logger);
        }
        return f.getCreatedClassName();
    }
}