com.github.jknack.handlebars.cache.GuavaTemplateCache.java Source code

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Here is the source code for com.github.jknack.handlebars.cache.GuavaTemplateCache.java

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/**
 * Copyright (c) 2012-2013 Edgar Espina
 *
 * This file is part of Handlebars.java.
 *
 * 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.github.jknack.handlebars.cache;

import static org.apache.commons.lang3.Validate.notNull;

import java.io.IOException;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

import com.github.jknack.handlebars.HandlebarsException;
import com.github.jknack.handlebars.Parser;
import com.github.jknack.handlebars.Template;
import com.github.jknack.handlebars.io.TemplateSource;
import com.google.common.cache.Cache;

/**
 * An implementation of {@link TemplateCache} built on top of Guava.
 *
 * @author edgar.espina
 * @since 0.11.0
 */
public class GuavaTemplateCache implements TemplateCache {

    /**
     * The guava cache.
     */
    private final Cache<TemplateSource, Template> cache;

    /**
     * Creates a new {@link GuavaTemplateCache}.
     *
     * @param cache The guava cache to use. Required.
     */
    public GuavaTemplateCache(final Cache<TemplateSource, Template> cache) {
        this.cache = notNull(cache, "The cache is required.");
    }

    @Override
    public void clear() {
        cache.invalidateAll();
    }

    @Override
    public void evict(final TemplateSource source) {
        cache.invalidate(source);
    }

    @Override
    public Template get(final TemplateSource source, final Parser parser) throws IOException {
        notNull(source, "The source is required.");
        notNull(parser, "The parser is required.");
        try {
            return cache.get(source, new Callable<Template>() {
                @Override
                public Template call() throws IOException {
                    return parser.parse(source);
                }
            });
        } catch (ExecutionException ex) {
            throw launderThrowable(source, ex.getCause());
        }
    }

    /**
     * Re-throw the cause of an execution exception.
     *
     * @param source The template source. Required.
     * @param cause The cause of an execution exception.
     * @return Re-throw a cause of an execution exception.
     */
    private RuntimeException launderThrowable(final TemplateSource source, final Throwable cause) {
        if (cause instanceof RuntimeException) {
            return (RuntimeException) cause;
        } else if (cause instanceof Error) {
            throw (Error) cause;
        } else {
            return new HandlebarsException("Can't parse: " + source, cause);
        }
    }
}