com.vmware.appfactory.taskqueue.tasks.state.builder.TafBuilder.java Source code

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Here is the source code for com.vmware.appfactory.taskqueue.tasks.state.builder.TafBuilder.java

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/* ***********************************************************************
 * VMware ThinApp Factory
 * Copyright (c) 2009-2013 VMware, Inc. All Rights Reserved.
 *
 * 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.vmware.appfactory.taskqueue.tasks.state.builder;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Map;

import javax.annotation.Nonnull;

import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.vmware.appfactory.taskqueue.tasks.state.HasBuilderChanges;

abstract class TafBuilder<API> {

    private final Map<String, HasBuilderChanges.BuilderChange> changes = Maps.newLinkedHashMap();
    private final Collection<HasBuilderChanges.BuilderChange> changeEvents;

    private final ImmutableMap<String, Method> resultClassGetters;
    private final ImmutableMap<String, Method> resultClassSetters;

    final Class<? extends API> resultClass;

    API builtResult;

    protected TafBuilder(Class<? extends API> resultClass) {
        this.resultClass = resultClass;
        this.resultClassGetters = BeanMaps.newBeanGetters(resultClass);
        this.resultClassSetters = BeanMaps.newBeanSetters(resultClass);
        this.changeEvents = Sets.newHashSetWithExpectedSize(resultClassGetters.size());
    }

    public abstract TafBuilder<API> withOriginal(API original);

    public API build() {
        if (null != this.builtResult) {
            return builtResult;
        }

        API localResult;
        try {
            localResult = this.resultClass.newInstance();
        } catch (InstantiationException e) {
            throw new Error(e);
        } catch (IllegalAccessException e) {
            throw new Error(e);
        }

        for (HasBuilderChanges.BuilderChange execute : changeValues()) {
            perRegularChange(execute, localResult);
        }

        if (localResult instanceof HasBuilderChanges) {
            perRegularChange(new HasBuilderChanges.BuilderChange("changes", changeEvents), localResult);
        }

        this.builtResult = localResult;
        return localResult;
    }

    public Collection<HasBuilderChanges.BuilderChange> changeValues() {
        return changes.values();
    }

    protected void perRegularChange(HasBuilderChanges.BuilderChange execute, API result) {
        Method setter = resultClassSetters.get(execute.getProperty());
        Object item;
        try {
            if (setter == null) {
                throw new NullPointerException("Readonly property [" + this.resultClass + '.'
                        + execute.getProperty() + "] missing setter");
            }
            item = execute.getValue();
            BeanMaps.optimisticSet(setter, result, item);
        } catch (Exception e) {
            if (e instanceof RuntimeException)
                throw (RuntimeException) e;
            throw new Error(e);
        }
    }

    protected void addChange(String property, Object object) {
        HasBuilderChanges.BuilderChange change = new HasBuilderChanges.BuilderChange(property, object);

        HasBuilderChanges.BuilderChange oldChange = changes.get(property);
        if (null != oldChange && !Objects.equal(oldChange.getValue(), object)) {
            // are we changing the value from the original?
            changeEvents.add(change);
        }

        changes.put(property, change);
    }

    protected void addChanges(@Nonnull API source) {
        Preconditions.checkNotNull(source);
        BeanMaps.BeanMapViaIntrospection<String> bm = BeanMaps.newBeanMap(source);
        for (Map.Entry<String, Object> entry : bm.entrySet()) {
            Object value = entry.getValue();
            String key = entry.getKey();
            if (!resultClassSetters.containsKey(entry.getKey())) {
                continue;
            }
            addChange(key, value);
        }
    }
}