Script.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * 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 org.culturegraph.mf.metamorph.functions;

import java.io.FileNotFoundException;

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

import org.culturegraph.mf.commons.ResourceUtil;
import org.culturegraph.mf.metamorph.api.MorphBuildException;
import org.culturegraph.mf.metamorph.api.MorphExecutionException;
import org.culturegraph.mf.metamorph.api.helpers.AbstractSimpleStatelessFunction;

/**
 * A function which executes a javascript function.
 *
 * @author Markus Michael Geipel
 */
public final class Script extends AbstractSimpleStatelessFunction {

	private Invocable invocable;
	private String invoke;

	public void setInvoke(final String invoke) {
		this.invoke = invoke;
	}

	public void setFile(final String file) {

		final ScriptEngineManager manager = new ScriptEngineManager();
		final ScriptEngine engine = manager.getEngineByName("JavaScript");
		try {
			// TODO: The script file should be loaded relatively to the base URI
			engine.eval(ResourceUtil.getReader(file));
		} catch (final ScriptException e) {
			throw new MorphBuildException("Error in script", e);
		} catch (final FileNotFoundException e) {
			throw new MorphBuildException("Error loading script '" + file + "'",
					e);
		}
		invocable = (Invocable) engine;
	}

	@Override
	public String process(final String value) {
		final Object obj;
		try {
			obj = invocable.invokeFunction(invoke, value);
			return obj.toString();
		} catch (final ScriptException e) {
			throw new MorphExecutionException(
					"Error in script while evaluating 'process' method", e);
		} catch (final NoSuchMethodException e) {
			throw new MorphExecutionException("'process' method is missing in script", e);
		}
	}

}