Make BTreeV2 generic with the record type

This allows b-trees to be used without casts.
jamesmudd · Mar 11, 2019 · e89f8ec · e89f8ec
1 parent 2ba1ce4
commit e89f8ec
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Showing 4 changed files with 17 additions and 21 deletions.
diff --git a/jhdf/src/main/java/io/jhdf/AbstractNode.java b/jhdf/src/main/java/io/jhdf/AbstractNode.java
@@ -19,7 +19,6 @@
 import io.jhdf.api.NodeType;
 import io.jhdf.btree.BTreeV2;
 import io.jhdf.btree.record.AttributeNameForIndexedAttributesRecord;
-import io.jhdf.btree.record.BTreeRecord;
 import io.jhdf.exceptions.HdfException;
 import io.jhdf.object.message.AttributeInfoMessage;
 import io.jhdf.object.message.AttributeMessage;
@@ -49,11 +48,11 @@ protected Map<String, Attribute> initialize() throws ConcurrentException {
 				if (attributeInfoMessage.getFractalHeapAddress() != Constants.UNDEFINED_ADDRESS) {
 					// Create the heap and btree
 					FractalHeap fractalHeap = new FractalHeap(hdfFc, attributeInfoMessage.getFractalHeapAddress());
-					BTreeV2 btree = BTreeV2.createBTree(hdfFc, attributeInfoMessage.getAttributeNameBTreeAddress());
+					BTreeV2<AttributeNameForIndexedAttributesRecord> btree = new BTreeV2<>(hdfFc,
+							attributeInfoMessage.getAttributeNameBTreeAddress());
 
 					// Read the attribute messages from the btree+heap
-					for (BTreeRecord record : btree.getRecords()) {
-						AttributeNameForIndexedAttributesRecord attributeRecord = (AttributeNameForIndexedAttributesRecord) record;
+					for (AttributeNameForIndexedAttributesRecord attributeRecord : btree.getRecords()) {
 						ByteBuffer bb = fractalHeap.getId(attributeRecord.getHeapId());
 						AttributeMessage attributeMessage = new AttributeMessage(bb, hdfFc.getSuperblock(),
 								attributeRecord.getFlags());

diff --git a/jhdf/src/main/java/io/jhdf/GroupImpl.java b/jhdf/src/main/java/io/jhdf/GroupImpl.java
@@ -18,7 +18,6 @@
 import io.jhdf.api.NodeType;
 import io.jhdf.btree.BTreeV1;
 import io.jhdf.btree.BTreeV2;
-import io.jhdf.btree.record.BTreeRecord;
 import io.jhdf.btree.record.LinkNameForIndexedGroupRecord;
 import io.jhdf.dataset.DatasetLoader;
 import io.jhdf.exceptions.HdfException;
@@ -64,12 +63,13 @@ private Map<String, Node> createNewStyleGroup(final ObjectHeader oh) {
 				logger.debug("Loaded group links from object header");
 			} else {
 				// Links are not stored compactly i.e in the fractal heap
-				final BTreeV2 bTreeNode = BTreeV2.createBTree(hdfFc, linkInfoMessage.getbTreeNameIndexAddress());
+				final BTreeV2<LinkNameForIndexedGroupRecord> bTreeNode = new BTreeV2<>(hdfFc,
+						linkInfoMessage.getbTreeNameIndexAddress());
 				final FractalHeap fractalHeap = new FractalHeap(hdfFc, linkInfoMessage.getFractalHeapAddress());
 
-				links = new ArrayList<>(); // TODO would be good to get the size here from the b-tree
-				for (BTreeRecord record : bTreeNode.getRecords()) {
-					LinkNameForIndexedGroupRecord linkName = (LinkNameForIndexedGroupRecord) record;
+				List<LinkNameForIndexedGroupRecord> records = bTreeNode.getRecords();
+				links = new ArrayList<>(records.size());
+				for (LinkNameForIndexedGroupRecord linkName : records) {
 					ByteBuffer id = linkName.getId();
 					// Get the name data from the fractal heap
 					ByteBuffer bb = fractalHeap.getId(id);

diff --git a/jhdf/src/main/java/io/jhdf/btree/BTreeV2.java b/jhdf/src/main/java/io/jhdf/btree/BTreeV2.java
@@ -13,7 +13,7 @@
 import io.jhdf.btree.record.BTreeRecord;
 import io.jhdf.exceptions.HdfException;
 
-public class BTreeV2 {
+public class BTreeV2<T extends BTreeRecord> {
 
 	private static final int NODE_OVERHEAD_BYTES = 10;
 
@@ -26,17 +26,13 @@ public class BTreeV2 {
 	/** Type of node. */
 	private final short nodeType;
 
-	private final List<BTreeRecord> records;
+	private final List<T> records;
 
-	public List<BTreeRecord> getRecords() {
+	public List<T> getRecords() {
 		return records;
 	}
 
-	public static BTreeV2 createBTree(HdfFileChannel hdfFc, long address) {
-		return new BTreeV2(hdfFc, address);
-	}
-
-	private BTreeV2(HdfFileChannel hdfFc, long address) {
+	public BTreeV2(HdfFileChannel hdfFc, long address) {
 		this.address = address;
 		try {
 			// B Tree V2 Header
@@ -82,7 +78,7 @@ private BTreeV2(HdfFileChannel hdfFc, long address) {
 	}
 
 	private void readRecords(HdfFileChannel hdfFc, long address, int nodeSize, int recordSize, int depth,
-			int numberOfRecords, int totalRecords, List<BTreeRecord> records) {
+			int numberOfRecords, int totalRecords, List<T> records) {
 
 		ByteBuffer bb = hdfFc.readBufferFromAddress(address, nodeSize);
 

diff --git a/jhdf/src/main/java/io/jhdf/btree/record/BTreeRecord.java b/jhdf/src/main/java/io/jhdf/btree/record/BTreeRecord.java
@@ -6,12 +6,13 @@
 
 public abstract class BTreeRecord {
 
-	public static BTreeRecord readRecord(byte type, ByteBuffer buffer) {
+	@SuppressWarnings("unchecked") // Requires that the b-tree is of the correct type for the record
+	public static <T extends BTreeRecord> T readRecord(byte type, ByteBuffer buffer) {
 		switch (type) {
 		case 5:
-			return new LinkNameForIndexedGroupRecord(buffer);
+			return (T) new LinkNameForIndexedGroupRecord(buffer);
 		case 8:
-			return new AttributeNameForIndexedAttributesRecord(buffer);
+			return (T) new AttributeNameForIndexedAttributesRecord(buffer);
 		default:
 			throw new HdfException("Unknown b-tree record type. Type = " + type);
 		}