HCOLL-147 factored ChronicleMap 'default-valuing' configuration from MapEventListener

src/main/java/net/openhft/chronicle/map/ConstantValueProvider.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2014 Higher Frequency Trading http://www.higherfrequencytrading.com
+ *
+ * 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 net.openhft.chronicle.map;
+
+import net.openhft.chronicle.map.serialization.BytesReader;
+import net.openhft.chronicle.map.serialization.MetaBytesWriter;
+import net.openhft.lang.io.ByteBufferBytes;
+
+import java.nio.ByteBuffer;
+
+final class ConstantValueProvider<K, V> implements DefaultValueProvider<K, V> {
+    private static final long serialVersionUID = 0L;
+
+    private transient V value;
+    private final int size;
+    private final byte[] serializedValueBytes;
+
+    <W> ConstantValueProvider(V value, MetaBytesWriter<V, W> metaValueWriter, W valueWriter) {
+        this.value = value;
+        size = (int) metaValueWriter.size(valueWriter, value);
+        serializedValueBytes = new byte[size];
+        ByteBufferBytes bytes = new ByteBufferBytes(ByteBuffer.wrap(serializedValueBytes));
+        metaValueWriter.write(valueWriter, bytes, value);
+    }
+
+    boolean wasDeserialized() {
+        return value == null;
+    }
+
+    void initTransients(BytesReader<V> reader) {
+        value = reader.read(new ByteBufferBytes(ByteBuffer.wrap(serializedValueBytes)), size);
+    }
+
+    @Override
+    public V get(K key, V usingValue) {
+        return value;
+    }
+}