com.google.template.soy.jbcsrc.internal.MemoryClassLoader.java Source code

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Here is the source code for com.google.template.soy.jbcsrc.internal.MemoryClassLoader.java

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/*
 * Copyright 2015 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.template.soy.jbcsrc.internal;

import com.google.common.collect.ImmutableMap;

/** A {@link ClassLoader} that can load classes from a configured set of {@code byte[]}s. */
public final class MemoryClassLoader extends AbstractMemoryClassLoader {
    static {
        // Since we only override findClass(), we can call this method to get fine grained locking
        // support with no additional work. Our superclass will lock all calls to findClass with a per
        // class to load lock, so we will never see concurrent loads of a single class.
        // See http://docs.oracle.com/javase/7/docs/technotes/guides/lang/cl-mt.html
        ClassLoader.registerAsParallelCapable();
    }

    /**
     * We store all the classes in this map and rely on normal classloading resolution.
     *
     * <p>The classloader will request classes via {@link #findClass(String)} as loading proceeds.
     */
    private final ImmutableMap<String, ClassData> classesByName;

    public MemoryClassLoader(Iterable<ClassData> classes) {
        this.classesByName = indexByClassname(classes);
    }

    public MemoryClassLoader(ClassLoader parent, Iterable<ClassData> classes) {
        super(parent);
        this.classesByName = indexByClassname(classes);
    }

    @Override
    protected ClassData getClassData(String name) {
        return classesByName.get(name);
    }

    private static ImmutableMap<String, ClassData> indexByClassname(Iterable<ClassData> classes) {
        ImmutableMap.Builder<String, ClassData> builder = ImmutableMap.builder();
        for (ClassData classData : classes) {
            builder.put(classData.type().className(), classData);
        }
        return builder.build();
    }
}