org.apache.jena.sparql.function.js.JSEngine Maven / Gradle / Ivy
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ARQ is a SPARQL 1.1 query engine for Apache Jena
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.jena.sparql.function.js;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Paths;
import javax.script.*;
import org.apache.jena.atlas.io.IO;
import org.apache.jena.riot.RiotNotFoundException;
import org.apache.jena.sparql.ARQConstants;
import org.apache.jena.sparql.ARQException;
import org.apache.jena.sparql.sse.builders.ExprBuildException;
/** Abstraction of a per-thread JavaScript execution system */
public class JSEngine {
private ScriptEngine scriptEngine;
private CompiledScript compiledScript;
private final Invocable invoc;
private String functions;
private String functionLibFile;
/** Create a {@code JSEngine} from a string. */
public static JSEngine createFromString(String functions) {
return new JSEngine(functions, null);
}
/** Create a {@code JSEngine} from the contents of a file. */
public static JSEngine createFromFile(String functionLibFile) {
return new JSEngine(null, functionLibFile);
}
/*package*/ JSEngine(String functions, String functionLibFile) {
this.functions = functions;
this.functionLibFile = functionLibFile;
invoc = build(functions, functionLibFile);
}
private static Invocable build(String functions, String functionLibFile) {
if ( functions == null && functionLibFile == null )
throw new ARQException("Both script string and script filename are null");
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine scriptEngine = manager.getEngineByName("nashorn");
Invocable invoc = (Invocable)scriptEngine;
if ( functionLibFile != null ) {
try {
Reader reader = Files.newBufferedReader(Paths.get(functionLibFile), StandardCharsets.UTF_8);
Object x = scriptEngine.eval(reader);
}
catch (NoSuchFileException | FileNotFoundException ex) {
throw new RiotNotFoundException("File: "+functionLibFile);
}
catch (IOException ex) { IO.exception(ex); }
catch (ScriptException e) {
throw new ExprBuildException("Failed to load Javascript", e);
}
}
if ( functions != null ) {
try {
Object x = scriptEngine.eval(functions);
}
catch (ScriptException e) {
throw new ExprBuildException("Failed to load Javascript", e);
}
}
// Try to call the init function - ignore NoSuchMethodException
try {
invoc.invokeFunction(ARQConstants.JavaScriptInitFunction);
} catch (NoSuchMethodException ex) {}
catch (ScriptException ex) {
throw new ARQException("Failed to call JavaScript initialization function", ex);
}
return invoc;
}
public Object call(String functionName, Object[] args) throws NoSuchMethodException, ScriptException {
return invoc.invokeFunction(functionName, args);
}
}