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    • nl.weeaboo.lua2.io.LuaSerializer Maven / Gradle / Ivy

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    package nl.weeaboo.lua2.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;

/**
 * Reads/writes Lua objects to a binary stream.
 */
public class LuaSerializer {

    private static final ThreadLocal CURRENT = new ThreadLocal<>();
    private final Environment env;

    private final List writeDelayed = new ArrayList<>();
    private final List readDelayed = new ArrayList<>();

    public LuaSerializer() {
        env = new Environment();
    }

    /**
     * @return The previously active {@link LuaSerializer}
     */
    protected LuaSerializer makeCurrent() {
        LuaSerializer previous = CURRENT.get();
        CURRENT.set(this);
        return previous;
    }

    /**
     * Returns the {@link LuaSerializer} that's in use on the current thread.
     */
    public static LuaSerializer getCurrent() {
        return CURRENT.get();
    }

    /**
     * Schedules an object for delayed writing. Delayed objects are written at the end of the stream. This can
     * greatly reduce the required stack size for (de)serializing large object graphs.
     */
    public void writeDelayed(Object obj) {
        writeDelayed.add(obj);
    }

    /**
     * Adds a callback to be notified when its matching 'delayed write' object is deserialized. Delayed
     * reads/writes are matched on order -- the order of calls to {@link #readDelayed(DelayedReader)} must
     * match those of {@link #writeDelayed(Object)}.
     */
    public void readDelayed(DelayedReader reader) {
        readDelayed.add(reader);
    }

    /**
     * Creates a new serializer.
     * @throws IOException If an I/O error occurs while initializing the serializer.
     */
    public ObjectSerializer openSerializer(OutputStream out) throws IOException {
        final LuaSerializer previous = makeCurrent();

        ObjectSerializer oout = new ObjectSerializer(out, env) {

            int delayedWritten = 0;

            private void writeDelayed() throws IOException {
                while (delayedWritten < writeDelayed.size()) {
                    writeObject(writeDelayed.get(delayedWritten++));
                }
            }

            @Override
            protected Callable createAsyncWriteTask(Object obj) {
                final Callable inner = super.createAsyncWriteTask(obj);

                return new Callable() {
                    @Override
                    public Void call() throws Exception {
                        makeCurrent();
                        inner.call();
                        writeDelayed();
                        return null;
                    }
                };
            }

            @Override
            public void close() throws IOException {
                try {
                    writeDelayed();
                } finally {
                    try {
                        super.close();
                    } finally {
                        writeDelayed.clear();
                        CURRENT.set(previous);
                    }
                }

                checkErrors();
            }
        };
        return oout;
    }

    /**
     * Creates a new deserializer.
     * @throws IOException If an I/O error occurs while initializing the deserializer.
     */
    public ObjectDeserializer openDeserializer(InputStream in) throws IOException {
        final LuaSerializer previous = makeCurrent();

        ObjectDeserializer oin = new ObjectDeserializer(in, env) {

            int delayedRead = 0;

            private void readDelayed() throws IOException {
                try {
                    while (delayedRead < readDelayed.size()) {
                        DelayedReader reader = readDelayed.get(delayedRead++);
                        reader.onRead(readObject());
                    }
                } catch (ClassNotFoundException cnfe) {
                    throw new IOException(cnfe.toString());
                }
            }

            @Override
            protected Callable createAsyncReadTask() {
                final Callable inner = super.createAsyncReadTask();

                return new Callable() {
                    @Override
                    public Object call() throws Exception {
                        makeCurrent();
                        Object result = inner.call();
                        readDelayed();
                        return result;
                    }
                };
            }

            @Override
            public void close() throws IOException {
                try {
                    readDelayed();
                } finally {
                    try {
                        super.close();
                    } finally {
                        readDelayed.clear();
                        CURRENT.set(previous);
                    }
                }
            }
        };
        return oin;
    }

    /** Returns the serialization environment. */
    public Environment getEnvironment() {
        return env;
    }

}
    
    
    
    

    




    
    
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