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/***** BEGIN LICENSE BLOCK *****
 * Version: CPL 1.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Common Public
 * License Version 1.0 (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.eclipse.org/legal/cpl-v10.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2008 JRuby project
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
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 * decision by deleting the provisions above and replace them with the notice
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 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the CPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.ext.ffi.jffi;

import com.kenai.jffi.CallingConvention;
import com.kenai.jffi.InvocationBuffer;
import org.jruby.RubyProc;
import org.jruby.ext.ffi.CallbackInfo;
import org.jruby.ext.ffi.Pointer;
import org.jruby.runtime.Block;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;

/**
 * Converts a ruby block or proc into a native callback.
 */
final class CallbackMarshaller implements ParameterMarshaller {
    private final CallbackInfo cbInfo;
    private final CallingConvention convention;

    public CallbackMarshaller(CallbackInfo cbInfo, CallingConvention convention) {
        this.cbInfo = cbInfo;
        this.convention = convention;
    }

    public void marshal(Invocation invocation, InvocationBuffer buffer, IRubyObject value) {
        marshal(invocation.getThreadContext(), buffer, value);
    }

    public void marshal(ThreadContext context, InvocationBuffer buffer, IRubyObject value) {
        if (value.isNil()) {
            buffer.putAddress(0);
        } else if (value instanceof RubyProc || value.respondsTo("call")) {
            marshalParam(context, buffer, value);
        } else {
            throw context.getRuntime().newTypeError("wrong argument type.  Expected callable object");
        }
    }

    private static final class CallbackReaper implements Runnable {
        private final CallbackManager.Callback cb;

        public CallbackReaper(CallbackManager.Callback cb) {
            this.cb = cb;
        }

        public void run() {
            cb.dispose();
        }
    }

    void marshal(Invocation session, InvocationBuffer buffer, Block value) {
        final CallbackManager.Callback cb = CallbackManager.getInstance().getCallback(session.getThreadContext().getRuntime(), cbInfo, value);
        buffer.putAddress(cb.getAddress());

        //
        // Adding a post-invoke for the cb result serves to both keep it alive
        // until after the function returns, and allows us to clean up the native
        // trampoline early, instead of letting them accumulate until a GC run
        //
        session.addPostInvoke(new CallbackReaper(cb));
    }

    private void marshalParam(ThreadContext context, InvocationBuffer buffer, Object value) {
        Pointer cb = CallbackManager.getInstance().getCallback(context.getRuntime(), cbInfo, value);
        buffer.putAddress(cb.getAddress());
    }

    public boolean requiresPostInvoke() {
        return true;
    }

    public boolean requiresReference() {
        return false;
    }
}