Add ByteBuffer slices

src/main/java/com/facebook/presto/AbstractSlice.java

@@ -0,0 +1,110 @@
+package com.facebook.presto;
+
+import com.google.common.base.Objects;
+import com.google.common.primitives.UnsignedBytes;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.FileChannel;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.charset.Charset;
+
+import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.lang.Math.min;
+
+public abstract class AbstractSlice
+        implements Slice
+{
+    @Override
+    public byte[] getBytes()
+    {
+        return getBytes(0, length());
+    }
+
+    @Override
+    public Slice copySlice()
+    {
+        return copySlice(0, length());
+    }
+
+    @Override
+    public SliceInput input()
+    {
+        return new SliceInput(this);
+    }
+
+    @Override
+    public SliceOutput output()
+    {
+        return new BasicSliceOutput(this);
+    }
+
+    @Override
+    public ByteBuffer toByteBuffer()
+    {
+        return toByteBuffer(0, length());
+    }
+
+    @Override
+    public String toString(Charset charset)
+    {
+        return toString(0, length(), charset);
+    }
+
+    @Override
+    public String toString(int index, int length, Charset charset)
+    {
+        if (length == 0) {
+            return "";
+        }
+        return Slices.decodeString(toByteBuffer(index, length), charset);
+    }
+
+    @Override
+    public String toString()
+    {
+        return Objects.toStringHelper(this)
+                .add("length", length())
+                .toString();
+    }
+
+    protected void checkIndexLength(int index, int length)
+    {
+        checkPositionIndexes(index, index + length, length());
+    }
+
+    protected static int channelRead(ReadableByteChannel in, ByteBuffer dst)
+            throws IOException
+    {
+        try {
+            return in.read(dst);
+        }
+        catch (ClosedChannelException e) {
+            return -1;
+        }
+    }
+
+    protected static int channelRead(FileChannel in, ByteBuffer dst, int position)
+            throws IOException
+    {
+        try {
+            return in.read(dst, position);
+        }
+        catch (ClosedChannelException e) {
+            return -1;
+        }
+    }
+
+    protected static int compareByteBuffers(ByteBuffer a, ByteBuffer b)
+    {
+        int length = min(a.capacity(), b.capacity());
+        for (int i = 0; i < length; i++) {
+            int v = UnsignedBytes.compare(a.get(i), b.get(i));
+            if (v != 0) {
+                return v;
+            }
+        }
+        return a.capacity() - b.capacity();
+    }
+}