com.cueup.hegemon.ScriptCache.java Source code

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Here is the source code for com.cueup.hegemon.ScriptCache.java

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/*
 * Copyright 2012 the hegemon authors.
 *
 * 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.cueup.hegemon;

import com.cueup.hegemon.compilation.CachedScriptCompilation;
import com.cueup.hegemon.compilation.ScriptCompilation;
import com.cueup.hegemon.compilation.SimpleScriptCompilation;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import javax.script.ScriptException;
import java.util.concurrent.ExecutionException;

/**
 * Cache of scripts.
 */
public class ScriptCache {

    private final LoadingCache<String, Script> cache;

    private static final ScriptCompilation DEFAULT_COMPILATION = new CachedScriptCompilation(
            new SimpleScriptCompilation(9));

    /**
     * Create a ScriptCache that loads scripts from the given LoadPath.
     * @param loadPath the LoadPath to load files from.
     */
    public ScriptCache(final LoadPath loadPath) {
        this(loadPath, DEFAULT_COMPILATION);
    }

    /**
     * Create a ScriptCache that loads scripts from the given LoadPath.
     * @param loadPath the LoadPath to load files from.
     * @param scriptCompilation the strategy to use to compile scripts.
     */
    public ScriptCache(final LoadPath loadPath, final ScriptCompilation scriptCompilation) {
        this.cache = CacheBuilder.newBuilder().build(new CacheLoader<String, Script>() {
            @Override
            public Script load(String key) throws Exception {
                return new Script(key, loadPath.load(key), scriptCompilation, loadPath);
            }
        });
    }

    /**
     * Clear the cache.
     */
    public void clear() {
        this.cache.invalidateAll();
    }

    /**
     * Get a script, optionally reloading.
     * @param script the name of the script to load.
     * @param reload whether or not to reload the script cleanly.
     * @return the Script with the given name.
     * @throws LoadError if the script file can't be located.
     * @throws ScriptException if the script doesn't evaluate correctly.
     */
    public Script get(String script, boolean reload) throws LoadError, ScriptException {
        try {
            if (reload) {
                this.cache.invalidate(script);
            }
            return this.cache.get(script);
        } catch (ExecutionException e) {
            if (e.getCause() instanceof ScriptException) {
                throw (ScriptException) e.getCause();
            } else if (e.getCause() instanceof LoadError) {
                throw (LoadError) e.getCause();
            } else if (e.getCause() instanceof RuntimeException) {
                throw (RuntimeException) e.getCause();
            } else {
                throw new RuntimeException("Impossible exception", e);
            }
        }
    }

    /**
     * Get a cached script.
     * @param script the name of the script to load.
     * @return the Script with the given name.
     * @throws LoadError if the script file can't be located.
     * @throws ScriptException if the script doesn't evaluate correctly.
     */
    public Script get(String script) throws LoadError, ScriptException {
        return get(script, false);
    }
}