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Native bindings to LibVLC used by the vlcj project.
There is a newer version: 5.0.0-M1
/*
 * This file is part of VLCJ.
 *
 * VLCJ is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * VLCJ is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with VLCJ.  If not, see .
 *
 * Copyright 2009-2019 Caprica Software Limited.
 */

package uk.co.caprica.vlcj.binding;

import com.sun.jna.Pointer;

/**
 * Encapsulation of access to native strings.
 * 
 * This class takes care of freeing the memory that was natively allocated for the string, if needed.
 * 

 * Generally, any native API that returns "const char*" must not be freed, so in such cases the native return
 * type mapping can actually be String rather than {@link Pointer}. Alternatively, {@link #copyNativeString(Pointer)}
 * can be used.
 * 

 * Generally, Any native API that returns "char*" must be freed, so in such cases the native return type
 * mapping must be {@link Pointer} and {@link #copyAndFreeNativeString(LibVlc, Pointer)} must be used.
 * 

 * Where a native string is contained in a {@link com.sun.jna.Structure} those strings should not be freed if
 * the structure itself is subsequently freed (usually by a companion release native method), so in these cases
 * {@link #copyNativeString(Pointer)} must be used.
 */
public final class NativeString {

    /**
     * Prevent direct instantiation by others.
     */
    private NativeString() {
    }

    /**
     * Get a String from a native string pointer, freeing the native string pointer when done.
     * 

     * If the native string pointer is not freed then a native memory leak will occur.
     * 

     * Use this method if the native string type is "char*", i.e. lacking the "const" modifier.
     *
     * @param libvlc native library instance
     * @param pointer pointer to native string, may be null
     * @return string, or null if the pointer was null
     */
    public static final String copyAndFreeNativeString(LibVlc libvlc, Pointer pointer) {
        if(pointer != null) {
            // Pointer.getString copies native memory to a Java String
            String result = pointer.getString(0);
            libvlc.libvlc_free(pointer);
            return result;
        }
        else {
            return null;
        }
    }

    /**
     * Copy a String from a native string pointer, without freeing the native pointer.
     * 
     * Use this method if the native string type is "const char*".
     *
     * @param pointer pointer to native string, may be null
     * @return string, or null if the pointer was null
     */
    public static final String copyNativeString(Pointer pointer) {
        if(pointer != null) {
            // Pointer.getString copies native memory to a Java String
            return pointer.getString(0);
        }
        else {
            return null;
        }
    }
}