Implement more BlockReader types

Adds additional useful block reader types.

* LayeredBlockReader, which represents priority

* SerialBlockReader, which concatenates readers

1 files changed, 70 insertions, 0 deletions

diff --git a/BJC-Utils2/src/main/java/bjc/utils/ioutils/LayeredBlockReader.java b/BJC-Utils2/src/main/java/bjc/utils/ioutils/LayeredBlockReader.java
new file mode 100644
index 0000000..ed7a1b9
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/ioutils/LayeredBlockReader.java
@@ -0,0 +1,70 @@
+package bjc.utils.ioutils;
+
+import java.io.IOException;
+
+/**
+ * A block reader that supports draining all the blocks from one reading before
+ * swapping to another.
+ * 
+ * This is more a 'prioritize blocks from one over the other', than a 'read all
+ * the blocks from one, then all the blocks from the other'. If you need that,
+ * look at {@link SerialBlockReader}.
+ * 
+ * @author bjculkin
+ *
+ */
+public class LayeredBlockReader implements BlockReader {
+	private BlockReader	first;
+	private BlockReader	second;
+
+	private int blockNo;
+
+	/**
+	 * Create a new layered block reader.
+	 * 
+	 * @param primary
+	 *                The first source to read blocks from.
+	 * 
+	 * @param secondary
+	 *                The second source to read blocks from.
+	 */
+	public LayeredBlockReader(BlockReader primary, BlockReader secondary) {
+		first = primary;
+		second = secondary;
+	}
+
+	@Override
+	public boolean hasNextBlock() {
+		return first.hasNextBlock() || second.hasNextBlock();
+	}
+
+	@Override
+	public Block getBlock() {
+		Block firstBlock = first.getBlock();
+
+		return firstBlock == null ? second.getBlock() : firstBlock;
+	}
+
+	@Override
+	public boolean nextBlock() {
+		boolean gotFirst = first.nextBlock();
+
+		boolean succ = gotFirst ? gotFirst : second.nextBlock();
+
+		if (succ) blockNo += 1;
+
+		return succ;
+	}
+
+	@Override
+	public int getBlockCount() {
+		return blockNo;
+	}
+
+	@Override
+	public void close() throws IOException {
+		second.close();
+
+		first.close();
+	}
+}
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