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A library for invoking native functions from java
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/*
 * Copyright (C) 2012 Wayne Meissner
 *
 * This file is part of the JNR project.
 *
 * 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.
 */

package jnr.ffi.provider.converters;

import jnr.ffi.Memory;
import jnr.ffi.Pointer;
import jnr.ffi.byref.ByReference;
import jnr.ffi.mapper.ToNativeContext;
import jnr.ffi.mapper.ToNativeConverter;
import jnr.ffi.provider.ParameterFlags;

/**
 *
 */
@ToNativeConverter.Cacheable
public class ByReferenceParameterConverter implements ToNativeConverter {
    private static final ToNativeConverter IN = new ByReferenceParameterConverter(ParameterFlags.IN);
    private static final ToNativeConverter OUT = new ByReferenceParameterConverter.Out(ParameterFlags.OUT);
    private static final ToNativeConverter INOUT = new ByReferenceParameterConverter.Out(ParameterFlags.IN | ParameterFlags.OUT);
    private final int parameterFlags;

    private ByReferenceParameterConverter(int parameterFlags) {
        this.parameterFlags = parameterFlags;
    }

    public static ToNativeConverter getInstance(ToNativeContext toNativeContext) {
        int parameterFlags = ParameterFlags.parse(toNativeContext.getAnnotations());
        return ParameterFlags.isOut(parameterFlags) ? ParameterFlags.isIn(parameterFlags) ? INOUT : OUT : IN;
    }

    public Pointer toNative(ByReference value, ToNativeContext context) {
        if (value == null) {
            return null;
        }

        Pointer memory =  Memory.allocate(context.getRuntime(), value.nativeSize(context.getRuntime()));
        if (ParameterFlags.isIn(parameterFlags)) {
            value.toNative(context.getRuntime(), memory, 0);
        }

        return memory;
    }

    public Class nativeType() {
        return Pointer.class;
    }

    public static final class Out extends ByReferenceParameterConverter implements ToNativeConverter.PostInvocation {
        public Out(int parameterFlags) {
            super(parameterFlags);
        }

        public void postInvoke(ByReference byReference, Pointer pointer, ToNativeContext context) {
            if (byReference != null && pointer != null) {
                byReference.fromNative(context.getRuntime(), pointer, 0);
            }
        }
    }
}