/*
* 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.nifi.processors.script.engine;
import clojure.lang.Compiler;
import clojure.lang.LineNumberingPushbackReader;
import clojure.lang.Namespace;
import clojure.lang.RT;
import clojure.lang.Symbol;
import clojure.lang.Var;
import javax.script.AbstractScriptEngine;
import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptException;
import javax.script.SimpleBindings;
import java.io.Reader;
import java.io.StringReader;
import java.util.UUID;
/**
* A ScriptEngine implementation for the Clojure language
*/
public class ClojureScriptEngine extends AbstractScriptEngine {
public static final String ENGINE_NAME = "Clojure";
public static final String ENGINE_VERSION = "1.8.0";
private volatile ScriptEngineFactory scriptEngineFactory;
private final String uuid = "ns-" + UUID.randomUUID().toString();
private final Symbol NAMESPACE_SYMBOL = Symbol.create(uuid);
protected ClojureScriptEngine(ScriptEngineFactory scriptEngineFactory) {
this.scriptEngineFactory = scriptEngineFactory;
// Set up the engine bindings
Bindings engineScope = getBindings(ScriptContext.ENGINE_SCOPE);
engineScope.put(ENGINE, ENGINE_NAME);
engineScope.put(ENGINE_VERSION, ENGINE_VERSION);
engineScope.put(NAME, ENGINE_NAME);
engineScope.put(LANGUAGE, ENGINE_NAME);
engineScope.put(LANGUAGE_VERSION, ENGINE_VERSION);
}
@Override
public Object eval(String script, ScriptContext context) throws ScriptException {
if (script == null) {
throw new NullPointerException("script is null");
}
return eval(new StringReader(script), context);
}
@Override
public Object eval(Reader reader, ScriptContext context) throws ScriptException {
try {
// Get engine bindings and send them to Clojure
Bindings engineBindings = context.getBindings(ScriptContext.ENGINE_SCOPE);
engineBindings.entrySet().forEach((entry) -> Var.intern(Namespace.findOrCreate(NAMESPACE_SYMBOL), Symbol.create(entry.getKey().intern()), entry.getValue(), true));
Var.pushThreadBindings(
RT.map(RT.CURRENT_NS, RT.CURRENT_NS.deref(),
RT.IN, new LineNumberingPushbackReader(context.getReader()),
RT.OUT, context.getWriter(),
RT.ERR, context.getErrorWriter()));
Object result = Compiler.load(reader);
return result;
} catch (Exception e) {
throw new ScriptException(e);
} finally {
Namespace.remove(NAMESPACE_SYMBOL);
}
}
@Override
public Bindings createBindings() {
return new SimpleBindings();
}
@Override
public ScriptEngineFactory getFactory() {
return scriptEngineFactory;
}
public String getNamespace() {
return uuid;
}
}