org.topbraid.shacl.js.NashornScriptEngine Maven / Gradle / Ivy
/*
* 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.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*/
package org.topbraid.shacl.js;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import org.apache.jena.query.QuerySolution;
import org.apache.jena.rdf.model.RDFNode;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.rdf.model.Statement;
import org.topbraid.jenax.util.ExceptionUtil;
import org.topbraid.jenax.util.JenaUtil;
import org.topbraid.shacl.js.model.JSFactory;
import org.topbraid.shacl.js.model.TermFactory;
import org.topbraid.shacl.vocabulary.SH;
/**
* Default implementation of JSScriptEngine, based on Nashorn.
*
* @author Holger Knublauch
*/
public class NashornScriptEngine implements JSScriptEngine {
private final static String ARGS_FUNCTION_NAME = "theGoodOldArgsFunction";
// Copied from https://davidwalsh.name/javascript-arguments
private final static String ARGS_FUNCTION =
"function " + ARGS_FUNCTION_NAME + "(funcString) {\n" +
" var args = funcString.match(/function\\s.*?\\(([^)]*)\\)/)[1];\n" +
" return args.split(',').map(function(arg) {\n" +
" return arg.replace(/\\/\\*.*\\*\\//, '').trim();\n" +
" }).filter(function(arg) {\n" +
" return arg;\n" +
" });\n" +
"}";
public static final String DASH_JS = "http://datashapes.org/js/dash.js";
public static final String RDFQUERY_JS = "http://datashapes.org/js/rdfquery.js";
private ScriptEngine engine;
private Map> functionParametersMap = new HashMap<>();
// Remembers which sh:libraries executables were already handled so that they are
// not installed twice
private Set visitedLibraries = new HashSet<>();
private Set loadedURLs = new HashSet<>();
public NashornScriptEngine() {
engine = findNashorn();
engine.put("TermFactory", new TermFactory());
try {
engine.eval(ARGS_FUNCTION);
}
catch(ScriptException ex) {
ExceptionUtil.throwUnchecked(ex);
}
}
private ScriptEngine findNashorn() {
ScriptEngine nashorn = new ScriptEngineManager().getEngineByName("nashorn");
if (nashorn == null) {
nashorn = new ScriptEngineManager(null).getEngineByName("nashorn");
}
if (nashorn == null) {
throw new RuntimeException("Oracle Nashorn not found in the current context");
}
return nashorn;
}
@Override
public Object eval(String expr) throws ScriptException {
return engine.eval(expr);
}
@Override
public void executeLibraries(Resource e) throws Exception {
for(Resource library : JenaUtil.getResourceProperties(e, SH.jsLibrary)) {
if(!visitedLibraries.contains(library)) {
visitedLibraries.add(library);
executeLibraries(library);
}
}
for(Statement s : e.listProperties(SH.jsLibraryURL).toList()) {
if(s.getObject().isLiteral()) {
String url = s.getString();
executeScriptFromURL(url);
}
}
}
@Override
public final void executeScriptFromURL(String url) throws Exception {
if(!loadedURLs.contains(url)) {
loadedURLs.add(url);
try ( Reader reader = createScriptReader(url) ) {
engine.eval(reader);
}
}
}
protected Reader createScriptReader(String url) throws Exception {
if(DASH_JS.equals(url)) {
return new InputStreamReader(NashornScriptEngine.class.getResourceAsStream("/js/dash.js"));
}
else if(RDFQUERY_JS.equals(url)) {
return new InputStreamReader(NashornScriptEngine.class.getResourceAsStream("/js/rdfquery.js"));
}
else {
return new InputStreamReader(new URL(url).openStream());
}
}
@Override
public Object get(String varName) {
return engine.get(varName);
}
public final ScriptEngine getEngine() {
return engine;
}
private List getFunctionParameters(String functionName) throws ScriptException {
List cached = functionParametersMap.get(functionName);
if(cached != null) {
return cached;
}
Object what = engine.get(functionName);
if(what == null) {
throw new ScriptException("Cannot find JavaScript function \"" + functionName + "\"");
}
try {
String funcString = what.toString();
Object result = ((Invocable) engine).invokeFunction(ARGS_FUNCTION_NAME, funcString);
Object[] params = NashornUtil.asArray(result);
List results = new ArrayList(params.length);
for(Object param : params) {
results.add((String)param);
}
functionParametersMap.put(functionName, results);
return results;
}
catch(Exception ex) {
throw new ScriptException(ex);
}
}
@Override
public Object invokeFunction(String functionName, QuerySolution bindings) throws javax.script.ScriptException, java.lang.NoSuchMethodException {
List functionParams = getFunctionParameters(functionName);
Object[] params = new Object[functionParams.size()];
Iterator varNames = bindings.varNames();
while(varNames.hasNext()) {
String varName = varNames.next();
int index = functionParams.indexOf(varName);
if(index < 0) {
index = functionParams.indexOf("$" + varName);
}
if(index >= 0) {
RDFNode value = bindings.get(varName);
if(value != null) {
params[index] = JSFactory.asJSTerm(value.asNode());
}
}
}
return invokeFunctionOrdered(functionName, params);
}
@Override
public Object invokeFunctionOrdered(String functionName, Object[] params)
throws ScriptException, NoSuchMethodException {
return ((Invocable) engine).invokeFunction(functionName, params);
}
@Override
public void put(String varName, Object value) {
engine.put(varName, value);
}
}