InvocablePhpScriptEngine.java

/*-*- mode: Java; tab-width:8 -*-*/

package php.java.script;

/*
 * Copyright (C) 2003-2007 Jost Boekemeier
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.lang.reflect.Proxy;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import javax.script.Bindings;
import javax.script.Invocable;
import javax.script.ScriptContext;
import javax.script.ScriptException;

import php.java.bridge.PhpProcedure;
import php.java.bridge.Util;
import php.java.bridge.http.IContext;

/**
 * This class implements the ScriptEngine and the Invocable interface.<p>
 * Example:
 * <blockquote>
 * <code>
 * ScriptEngine e = (new ScriptEngineManager()).getEngineByName("php-invocable");<br>
 * e.eval(&lt;? function f() {return java_server_name();}?&gt;<br>
 * System.out.println(((Invocable)e).invokeFunction("f", new Object[]{}));<br>
 * ((Closeable)e).close();<br>
 * </code>
 * </blockquote><br>
 * Another example which invokes a remote PHP "method" bound in the closed-over PHP environment. The PHP script "hello.php":
 * <blockquote>
 * <code>
 * &lt;?php require_once("java/Java.inc");<br>
 * function f() {return java_server_name();};<br>
 * java_call_with_continuation(java_closure());<br>
 * ?&gt;<br>
 * </code>
 * </blockquote><br>
 *  The Java code:
 * <blockquote>
 * <code>
 * ScriptEngine e = (new ScriptEngineManager()).getEngineByName("php-invocable");<br>
 * e.eval(new php.java.script.URLReader(new URL("http://localhost/hello.php")));<br>
 * System.out.println(((Invocable)e).invokeMethod(e.get("php.java.bridge.PhpProcedure"), "f", new Object[]{}));<br>
 * ((Closeable)e).close();<br>
 * </code>
 * </blockquote>
 */
public class InvocablePhpScriptEngine extends AbstractPhpScriptEngine implements Invocable {
    private static final String X_JAVABRIDGE_INCLUDE = Util.X_JAVABRIDGE_INCLUDE;
    private static final String PHP_JAVA_CONTEXT_CALL_JAVA_CLOSURE = "<?php java_context()->call(java_closure()); ?>";
    protected static final Object EMPTY_INCLUDE = "@";
    private static boolean registeredHook = false;
    private static final List engines = new LinkedList();
    private static final String PHP_EMPTY_SCRIPT = "<?php ?>";
     
    /**
     * Create a new ScriptEngine with a default context.
     */
    public InvocablePhpScriptEngine() {
	this(new PhpScriptEngineFactory());
    }

    /**
     * Create a new ScriptEngine from a factory.
     * @param factory The factory
     * @see #getFactory()
     */
    public InvocablePhpScriptEngine(PhpScriptEngineFactory factory) {
        super(factory);
    }
    /**
     * Create a new ScriptEngine with bindings.
     * @param n the bindings
     */
    public InvocablePhpScriptEngine(Bindings n) {
	this();
	setBindings(n, ScriptContext.ENGINE_SCOPE);
    }

    /* (non-Javadoc)
     * @see javax.script.Invocable#call(java.lang.String, java.lang.Object[])
     */
    protected Object invoke(String methodName, Object[] args)
	throws ScriptException, NoSuchMethodException {
	if (methodName==null) { release(); return null; }
	
	if(scriptClosure==null) {
	    if (Util.logLevel>4) Util.warn("Evaluating an empty script either because eval() has not been called or release() has been called.");
	    eval(PHP_EMPTY_SCRIPT);
	}
	try {
	    return invoke(scriptClosure, methodName, args);
	} catch (php.java.bridge.Request.AbortException e) {
	    release ();
	    throw new ScriptException(e);
	} catch (NoSuchMethodError e) { // conform to jsr223
	    throw new NoSuchMethodException(String.valueOf(e.getMessage()));
	}
    }
    /**{@inheritDoc}*/
    public Object invokeFunction(String methodName, Object[] args)
	throws ScriptException, NoSuchMethodException {
	return invoke(methodName, args);
    }

    private void checkPhpClosure(Object thiz) {
	if(thiz==null) throw new IllegalStateException("PHP script did not pass its continuation to us!. Please check if the previous call to eval() reported any errors. Or else check if it called OUR continuation.");
    }
    /* (non-Javadoc)
     * @see javax.script.Invocable#call(java.lang.String, java.lang.Object, java.lang.Object[])
     */
    protected Object invoke(Object thiz, String methodName, Object[] args)
	throws ScriptException, NoSuchMethodException {
	checkPhpClosure(thiz);
	PhpProcedure proc = (PhpProcedure)(Proxy.getInvocationHandler(thiz));
	try {
	    return proc.invoke(script, methodName, args);
	} catch (ScriptException e) {
	    throw e;
	} catch (NoSuchMethodException e) {
	    throw e;
	} catch (RuntimeException e) {
	    throw e; // don't wrap RuntimeException
	} catch (NoSuchMethodError e) { // conform to jsr223
	    throw new NoSuchMethodException(String.valueOf(e.getMessage()));
	} catch (Error er) {
	    throw er;
	} catch (Throwable e) {
	    throw new PhpScriptException("Invocation threw exception ", e);
	}
    }
    /**{@inheritDoc}*/
    public Object invokeMethod(Object thiz, String methodName, Object[] args)
	throws ScriptException, NoSuchMethodException {
	return invoke(thiz, methodName, args);
    }

    /**{@inheritDoc}*/
    public Object getInterface(Class clasz) {
	checkPhpClosure(script);
	return getInterface(script, clasz);
    }
    /**{@inheritDoc}*/
    public Object getInterface(Object thiz, Class clasz) {
	checkPhpClosure(thiz);
	Class[] interfaces = clasz==null?Util.ZERO_PARAM:new Class[]{clasz};
	return PhpProcedure.createProxy(interfaces, (PhpProcedure)Proxy.getInvocationHandler(thiz));
    }
    protected Reader getLocalReader(Reader reader, boolean embedJavaInc) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        Writer w = new OutputStreamWriter(out);

        String stdHeader = embedJavaInc ? null : ((IContext)getContext()).getRedirectURL("/JavaBridge");
        Reader localReader = new StringReader(getStandardHeader(stdHeader));

        char[] buf = new char[Util.BUF_SIZE];
        int c;
        try {
            /* header: <? require_once("http://localhost:<ourPort>/JavaBridge/java/Java.inc"); ?> */
            while((c=localReader.read(buf))>0) w.write(buf, 0, c);
            localReader.close(); localReader = null;
    
            /* the script: */
            while((c=reader.read(buf))>0) w.write(buf, 0, c);
    
            /* get the default, top-level, closure and call it, to stop the script from terminating */
            localReader =  new StringReader(PHP_JAVA_CONTEXT_CALL_JAVA_CLOSURE);
            while((c=localReader.read(buf))>0) w.write(buf, 0, c);
            localReader.close(); localReader = null;
            w.close(); w = null;
    
            /* now evaluate our script */
            localReader = new InputStreamReader(new ByteArrayInputStream(out.toByteArray()));
            return localReader;
        } finally {
	    if (w!=null) try {w.close();} catch (IOException e) {/*ignore*/}
        }
    }
    
    protected Object doEvalPhp(Reader reader, ScriptContext context) throws ScriptException {
	if (reader instanceof URLReader) return eval((URLReader)reader, context);
	
        if((continuation != null) || (reader == null) ) release();
  	if(reader==null) return null;
  	
  	setNewContextFactory();
	env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);
	Reader localReader = null;
        try {
            localReader = getLocalReader(reader, false);
            this.script = doEval(localReader, context);
            if (this.script!=null) {
        	/* get the proxy, either the one from the user script or our default proxy */
        	this.scriptClosure = script;
            }
	} catch (Exception e) {
	    Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException)e;
            if (e instanceof ScriptException) throw (ScriptException)e;
            throw new ScriptException(e);
       } finally {
            if(localReader!=null) try { localReader.close(); } catch (IOException e) {/*ignore*/}            
            handleRelease();
        }
       return resultProxy;
    }
    protected Object doEvalCompiledPhp(Reader reader, ScriptContext context) throws ScriptException {
        if((continuation != null) || (reader == null) ) release();
  	if(reader==null) return null;
  	
  	setNewContextFactory();
	env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);
        try {
            this.script = doEval(reader, context);
            if (this.script!=null) {
        	/* get the proxy, either the one from the user script or our default proxy */
        	this.scriptClosure = script;
            }
	} catch (Exception e) {
	    Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException)e;
            if (e instanceof ScriptException) throw (ScriptException)e;
            throw new ScriptException(e);
       } finally {
            handleRelease();
        }
       return resultProxy;
    }

    protected Object eval(URLReader reader, ScriptContext context) throws ScriptException {
        if((continuation != null) || (reader == null) ) release();
  	if(reader==null) return null;
  	
  	setNewContextFactory();
	env.put(X_JAVABRIDGE_INCLUDE, EMPTY_INCLUDE);
	
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        Writer w = new OutputStreamWriter(out);
        try {
            this.script = doEval(reader, context);
            if (this.script!=null) {
        	/* get the proxy, either the one from the user script or our default proxy */
        	this.scriptClosure = script;
            }
	} catch (Exception e) {
	    Util.printStackTrace(e);
            if (e instanceof RuntimeException) throw (RuntimeException)e;
            if (e instanceof ScriptException) throw (ScriptException)e;
            throw new ScriptException(e);
       } finally {
            if(w!=null)  try { w.close(); } catch (IOException e) {/*ignore*/}
            handleRelease();
        }
       return resultProxy;
    }

    protected void handleRelease() {
        // make sure to properly release them upon System.exit().
        synchronized(engines) {
            if(!registeredHook) {
        	registeredHook = true;
        	try {
        	    Runtime.getRuntime().addShutdownHook(new Util.Thread() {
        		public void run() {
        		    if (engines==null) return;
        		    synchronized(engines) {
        			for(Iterator ii = engines.iterator(); ii.hasNext(); ii.remove()) {
        			    InvocablePhpScriptEngine e = (InvocablePhpScriptEngine) ii.next();
        			    e.releaseInternal();
        			}
        		    }
        		}});
        	} catch (SecurityException e) {/*ignore*/}
            }
            engines.add(this);
        }
    }
    private void releaseInternal() {
	super.release();
    }
    /**{@inheritDoc}*/
    public void release() {
	synchronized(engines) {
	    releaseInternal();
	    engines.remove(this);
	}
    }
}