/*
* 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.wicketstuff.console.engine;
import java.io.ByteArrayOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.io.StringReader;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import clojure.lang.Associative;
import clojure.lang.Compiler;
import clojure.lang.Namespace;
import clojure.lang.PersistentHashMap;
import clojure.lang.RT;
import clojure.lang.Symbol;
import clojure.lang.Var;
/**
* Executes Clojure code.
* <p>
* stdout and stderr are captured. Bindings are pushed into user namespace, so to access a binding
* named "foo" use "user/foo". *
*
* @author cretzel
*/
public class ClojureEngine implements IScriptEngine
{
/**
* {@inheritDoc}
*/
public synchronized IScriptExecutionResult execute(final String script)
{
return execute(script, null);
}
/**
* {@inheritDoc}
*/
public synchronized IScriptExecutionResult execute(final String script,
final Map<String, Object> bindings)
{
Throwable exception = null;
String output = null;
Object returnValue = null;
final PrintStream oldOut = System.out;
final PrintStream oldErr = System.err;
final ByteArrayOutputStream bout = new ByteArrayOutputStream();
final PrintStream newOut = new PrintStream(bout, false);
final OutputStreamWriter newRtOut = new OutputStreamWriter(newOut);
boolean threadBindingPushed = false;
try
{
System.setOut(newOut);
System.setErr(newOut);
Associative mappings = PersistentHashMap.EMPTY;
mappings = mappings.assoc(RT.CURRENT_NS, RT.CURRENT_NS.get());
mappings = mappings.assoc(RT.OUT, newRtOut);
mappings = mappings.assoc(RT.ERR, newRtOut);
mappings = applyBindings(bindings, mappings);
Var.pushThreadBindings(mappings);
threadBindingPushed = true;
returnValue = Compiler.load(new StringReader(script));
}
catch (final Exception e)
{
exception = e;
}
finally
{
try
{
if (threadBindingPushed)
{
Var.popThreadBindings();
}
newRtOut.flush();
newRtOut.close();
System.setOut(oldOut);
System.setErr(oldErr);
output = bout.toString();
}
catch (final Exception e1)
{
ScriptEngineException see;
if (exception == null)
{
see = new ScriptEngineException(e1);
}
else
{
see = new ScriptEngineException("Failed to handle original exception: " +
exception, e1);
}
throw see;
}
}
return new DefaultScriptExecutionResult(script, exception, output, returnValue);
}
private Associative applyBindings(final Map<String, Object> bindings, Associative mappings)
{
if (bindings != null)
{
final Set<Entry<String, Object>> entrySet = bindings.entrySet();
for (final Entry<String, Object> entry : entrySet)
{
final Symbol symbol = Symbol.intern(entry.getKey());
final Namespace userNs = Namespace.findOrCreate(Symbol.create("user".intern()));
final Var var = Var.intern(userNs, symbol);
var.setDynamic(true);
mappings = mappings.assoc(var, entry.getValue());
}
}
return mappings;
}
}