package org.apache.velocity.runtime.parser.node;
/*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Velocity", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
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* ====================================================================
*
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* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
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*/
import java.lang.reflect.Method;
import java.io.*;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.parser.*;
import org.apache.velocity.util.introspection.Introspector;
import org.apache.velocity.util.introspection.IntrospectionCacheData;
import org.apache.velocity.exception.MethodInvocationException;
import java.lang.reflect.InvocationTargetException;
import org.apache.velocity.app.event.EventCartridge;
import org.apache.velocity.app.event.MethodExceptionEventHandler;
/**
* ASTMethod.java
*
* Method support for references : $foo.method()
*
* NOTE :
*
* introspection is now done at render time.
*
* Please look at the Parser.jjt file which is
* what controls the generation of this class.
*
* @author <a href="mailto:jvanzyl@periapt.com">Jason van Zyl</a>
* @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
* @version $Id: ASTMethod.java,v 1.20 2001/09/09 21:49:11 geirm Exp $
*/
public class ASTMethod extends SimpleNode
{
private String methodName = "";
private int paramCount = 0;
private Object [] params;
public ASTMethod(int id)
{
super(id);
}
public ASTMethod(Parser p, int id)
{
super(p, id);
}
/** Accept the visitor. **/
public Object jjtAccept(ParserVisitor visitor, Object data)
{
return visitor.visit(this, data);
}
/**
* simple init - init our subtree and get what we can from
* the AST
*/
public Object init( InternalContextAdapter context, Object data)
throws Exception
{
super.init( context, data );
/*
* this is about all we can do
*/
methodName = getFirstToken().image;
paramCount = jjtGetNumChildren() - 1;
params = new Object[paramCount];
return data;
}
/**
* does the instrospection of the class for the method needed.
* Note, as this calls value() on the args if any, this must
* only be called at execute() / render() time
*/
private Method doIntrospection( InternalContextAdapter context, Class data)
throws MethodInvocationException, Exception
{
/*
* Now the parameters have to be processed, there
* may be references contained within that need
* to be introspected.
*/
for (int j = 0; j < paramCount; j++)
params[j] = jjtGetChild(j + 1).value(context);
Method m = rsvc.getIntrospector().getMethod( data, methodName, params);
return m;
}
/**
* invokes the method. Returns null if a problem, the
* actual return if the method returns something, or
* an empty string "" if the method returns void
*/
public Object execute(Object o, InternalContextAdapter context)
throws MethodInvocationException
{
/*
* new strategy (strategery!) for introspection. Since we want
* to be thread- as well as context-safe, we *must* do it now,
* at execution time. There can be no in-node caching,
* but if we are careful, we can do it in the context.
*/
Method method = null;
try
{
/*
* check the cache
*/
IntrospectionCacheData icd = context.icacheGet( this );
Class c = o.getClass();
/*
* like ASTIdentifier, if we have cache information, and the
* Class of Object o is the same as that in the cache, we are
* safe.
*/
if ( icd != null && icd.contextData == c )
{
/*
* sadly, we do need recalc the values of the args, as this can
* change from visit to visit
*/
for (int j = 0; j < paramCount; j++)
params[j] = jjtGetChild(j + 1).value(context);
/*
* and get the method from the cache
*/
method = (Method) icd.thingy;
}
else
{
/*
* otherwise, do the introspection, and then
* cache it
*/
method = doIntrospection( context, c );
if (method != null)
{
icd = new IntrospectionCacheData();
icd.contextData = c;
icd.thingy = method;
context.icachePut( this, icd );
}
}
/*
* if we still haven't gotten the method, either we are calling
* a method that doesn't exist (which is fine...) or I screwed
* it up.
*/
if (method == null)
return null;
}
catch( MethodInvocationException mie )
{
/*
* this can come from the doIntrospection(), as the arg values
* are evaluated to find the right method signature. We just
* want to propogate it here, not do anything fancy
*/
throw mie;
}
catch( Exception e )
{
/*
* can come from the doIntropection() also, from Introspector
*/
rsvc.error("ASTMethod.execute() : exception from introspection : " + e);
return null;
}
try
{
/*
* get the returned object. It may be null, and that is
* valid for something declared with a void return type.
* Since the caller is expecting something to be returned,
* as long as things are peachy, we can return an empty
* String so ASTReference() correctly figures out that
* all is well.
*/
Object obj = method.invoke(o, params);
if (obj == null)
{
if( method.getReturnType() == Void.TYPE)
return new String("");
}
return obj;
}
catch( InvocationTargetException ite )
{
/*
* In the event that the invocation of the method
* itself throws an exception, we want to catch that
* wrap it, and throw. We don't log here as we want to figure
* out which reference threw the exception, so do that
* above
*/
EventCartridge ec = context.getEventCartridge();
/*
* if we have an event cartridge, see if it wants to veto
* also, let non-Exception Throwables go...
*/
if ( ec != null && ite.getTargetException() instanceof java.lang.Exception)
{
try
{
return ec.methodException( o.getClass(), methodName, (Exception)ite.getTargetException() );
}
catch( Exception e )
{
throw new MethodInvocationException(
"Invocation of method '"
+ methodName + "' in " + o.getClass()
+ " threw exception "
+ e.getClass() + " : " + e.getMessage(),
e, methodName );
}
}
else
{
/*
* no event cartridge to override. Just throw
*/
throw new MethodInvocationException(
"Invocation of method '"
+ methodName + "' in " + o.getClass()
+ " threw exception "
+ ite.getTargetException().getClass() + " : "
+ ite.getTargetException().getMessage(),
ite.getTargetException(), methodName );
}
}
catch( Exception e )
{
rsvc.error("ASTMethod.execute() : exception invoking method '"
+ methodName + "' in " + o.getClass() + " : " + e );
return null;
}
}
}