From c82e3b3b2de0633317ec8fc85925e91422820597 Mon Sep 17 00:00:00 2001
From: "Benjamin J. Culkin" <bjculkin@mix.wvu.edu>
Date: Sun, 8 Oct 2017 22:39:59 -0300
Subject: Start splitting into maven modules

---
 .../utils/ioutils/blocks/LayeredBlockReader.java   | 81 ++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 base/src/main/java/bjc/utils/ioutils/blocks/LayeredBlockReader.java

(limited to 'base/src/main/java/bjc/utils/ioutils/blocks/LayeredBlockReader.java')

diff --git a/base/src/main/java/bjc/utils/ioutils/blocks/LayeredBlockReader.java b/base/src/main/java/bjc/utils/ioutils/blocks/LayeredBlockReader.java
new file mode 100644
index 0000000..967a1f2
--- /dev/null
+++ b/base/src/main/java/bjc/utils/ioutils/blocks/LayeredBlockReader.java
@@ -0,0 +1,81 @@
+package bjc.utils.ioutils.blocks;
+
+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 {
+	/*
+	 * The readers to drain from.
+	 */
+	private final BlockReader first;
+	private final BlockReader second;
+
+	/*
+	 * The current block number.
+	 */
+	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(final BlockReader primary, final BlockReader secondary) {
+		first = primary;
+		second = secondary;
+	}
+
+	@Override
+	public boolean hasNextBlock() {
+		return first.hasNextBlock() || second.hasNextBlock();
+	}
+
+	@Override
+	public Block getBlock() {
+		final Block firstBlock = first.getBlock();
+
+		/*
+		 * Only drain a block from the second reader if none are
+		 * available in the first reader.
+		 */
+		return firstBlock == null ? second.getBlock() : firstBlock;
+	}
+
+	@Override
+	public boolean nextBlock() {
+		final boolean gotFirst = first.nextBlock();
+		final 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();
+	}
+}
-- 
cgit v1.2.3