build the tree iteratively

Author: pa314159

README.md

@@ -9,15 +9,15 @@ Add *merkle-tree* as a dependency to your project.
 * Gradle
 
 ```
-  implementation 'ascelion.public:merkle-tree:1.0.2'
+  implementation 'ascelion.public:merkle-tree:1.0.4'
 ```
 
 * Maven
 ````
   <dependency>
     <groupId>ascelion.public</groupId>
     <artifactId>merkle-tree</artifactId>
-    <version>1.0.2</version>
+    <version>1.0.4</version>
   </dependency>
 ````
 

impl/src/main/java/ascelion/merkle/TreeBuilder.java

@@ -110,7 +110,7 @@ int count() {
 	}
 
 	// the hash function
-	public final UnaryOperator<T> hashFn;
+	private final UnaryOperator<T> hashFn;
 	// the concatenation function
 	private final BinaryOperator<T> concatFn;
 	// supplier for the value of filler
@@ -266,6 +266,16 @@ public TreeRoot<T> build(Collection<TreeLeaf<T, ?>> leaves) {
 		return root;
 	}
 
+	/**
+	 * Calculates the hash of the input value using the hash operator of this builder.
+	 *
+	 * @param value the value to be hashed.
+	 * @return the hash value of the input value.
+	 */
+	public T hash(T value) {
+		return this.hashFn.apply(value);
+	}
+
 	/**
 	 * Checks whether a hash chain is valid using the operators of this builder instance.
 	 *
@@ -291,9 +301,9 @@ public boolean isValid(List<T> chain, int index, BiPredicate<T, T> eq) {
 			final T next = chain.get(k);
 
 			if ((index & 1) == 0) {
-				hash = this.hashFn.apply(this.concatFn.apply(hash, next));
+				hash = hash(this.concatFn.apply(hash, next));
 			} else {
-				hash = this.hashFn.apply(this.concatFn.apply(next, hash));
+				hash = hash(this.concatFn.apply(next, hash));
 			}
 
 			index >>>= 1;
@@ -302,21 +312,17 @@ public boolean isValid(List<T> chain, int index, BiPredicate<T, T> eq) {
 		return eq.test(hash, chain.get(chain.size() - 1));
 	}
 
-	private Root<T> doBuild(TreeNode<T>[] leaves) {
+	private Root<T> doBuild(TreeNode<T>[] nodes) {
 		// expecting a power of two
-		assert bitCount(leaves.length) == 1;
+		assert bitCount(nodes.length) == 1;
 
-		if (leaves.length == 2) {
-			return newNode(leaves[0], leaves[1], true);
-		}
-
-		final TreeNode<T>[] parents = new TreeNode[leaves.length / 2];
-
-		for (int i = 0; i < leaves.length; i += 2) {
-			parents[i / 2] = newNode(leaves[i], leaves[i + 1], false);
+		for (int count = nodes.length; count > 2; count /= 2) {
+			for (int i = 0; i < count; i += 2) {
+				nodes[i / 2] = newNode(nodes[i], nodes[i + 1], false);
+			}
 		}
 
-		return doBuild(parents);
+		return newNode(nodes[0], nodes[1], true);
 	}
 
 	private <N extends TreeNode<T>> N newNode(TreeNode<T> left, TreeNode<T> right, boolean root) {

impl/src/main/java/ascelion/merkle/help/DataSlice.java

@@ -43,7 +43,7 @@ static public TreeRoot<byte[]> buildTree(TreeBuilder<byte[]> bld, int size, Inpu
 		byte[] data;
 
 		while ((data = readNBytes(ist, size)).length > 0) {
-			bld.collect(new DataSlice(bld.hashFn.apply(data), data));
+			bld.collect(new DataSlice(bld.hash(data), data));
 		}
 
 		return bld.build();
@@ -68,7 +68,7 @@ static public TreeRoot<byte[]> buildTree(TreeBuilder<byte[]> bld, int size, Byte
 
 			buf.get(data, 0, data.length);
 
-			bld.collect(new DataSlice(bld.hashFn.apply(data), data));
+			bld.collect(new DataSlice(bld.hash(data), data));
 
 			buf.clear();
 		}

impl/src/main/java/overview.html

@@ -12,7 +12,7 @@ <h2 id="usage">Usage</h2>
 <li>Gradle</li>
 </ul>
 
-<pre><code>  implementation 'ascelion.public:merkle-tree:1.0.2'
+<pre><code>  implementation 'ascelion.public:merkle-tree:1.0.4'
 </code></pre>
 
 <ul>
@@ -22,7 +22,7 @@ <h2 id="usage">Usage</h2>
 <pre><code class="` language-`">  &lt;dependency&gt;
     &lt;groupId&gt;ascelion.public&lt;/groupId&gt;
     &lt;artifactId&gt;merkle-tree&lt;/artifactId&gt;
-    &lt;version&gt;1.0.2&lt;/version&gt;
+    &lt;version&gt;1.0.4&lt;/version&gt;
   &lt;/dependency&gt;
 </code></pre>