package com.airhacks.enhydrator.transform;
/*
* #%L
* enhydrator
* %%
* Copyright (C) 2014 Adam Bien
* %%
* 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.
* #L%
*/
import com.airhacks.enhydrator.in.Row;
import java.util.function.Consumer;
import javax.script.Bindings;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
/**
*
* @author airhacks.com
*/
public class Expression {
private final ScriptEngineManager manager;
private final ScriptEngine engine;
private Consumer<String> expressionListener;
public Expression() {
this(l -> {
});
}
public Expression(Consumer<String> expressionListener) {
this.expressionListener = expressionListener;
this.manager = new ScriptEngineManager();
this.engine = manager.getEngineByName("nashorn");
}
public Row execute(Row input, String expression) {
Bindings bindings = this.engine.createBindings();
bindings.put("$ROW", input);
bindings.put("$EMPTY", new Row(input.getIndex()));
try {
this.expressionListener.accept("Executing: " + expression);
Object result = this.engine.eval(expression, bindings);
this.expressionListener.accept("Got result: " + result);
if (!(result instanceof Row)) {
return input;
} else {
return (Row) result;
}
} catch (ScriptException ex) {
throw new IllegalStateException(ex.getMessage(), ex);
}
}
}