Extra lattice branch testing

Author: mikera

convex-core/src/main/java/convex/core/data/ACell.java

@@ -436,8 +436,8 @@ public int getBranchCount() {
 		for (int i=0; i<rc; i++) {
 			Ref<?> r=c.getRef(i);
 			if (r.isEmbedded()) {
-				ACell child=r.getValue();
-				if (child!=null) result+=child.getBranchCount();
+				// need to recursively count branches in embedded Ref
+				result+=r.branchCount();
 			} else {
 				// we found a branch!
 				result+=1;
@@ -460,12 +460,12 @@ public <T extends ACell> Ref<T> getBranchRef(int index) {
 			Ref<?> r=c.getRef(i);
 			if (r.isEmbedded()) {
 				ACell child=r.getValue();
-				if (child==null) continue; // no branch here
+				if (child==null) continue; // no branch here!
 				int cbc=child.getBranchCount();
 				if (cbc>index) return child.getBranchRef(index);
 				index-=cbc;
 			} else {
-				if (index==0) return (Ref<T>) r;
+				if (index==0) return (Ref<T>) r; // we are pointing to exactly this branch
 				index-=1;
 			}
 		}
@@ -573,7 +573,7 @@ public void attachRef(Ref<?> ref) {
 	}
 
 	/**
-	 * Tests if this Cell is completely encoded, i.e. has no external Refs. This implies that the 
+	 * Tests if this Cell is completely encoded, i.e. has no external branch Refs. This implies that the 
 	 * complete Cell can be represented in a single encoding.
 	 * @return true if completely encoded, false otherwise
 	 */

convex-core/src/main/java/convex/core/data/Cells.java

@@ -19,8 +19,9 @@ public class Cells {
 
 	/**
 	 * The maximum number of branches possible from a single Cell encoding
+	 * TODO: Verify this is 68 (vector with 16 embedded children with 4 branches each + embedded tail with 4 branches)
 	 */
-	public static final int MAX_BRANCH_COUNT = 72;
+	public static final int MAX_BRANCH_COUNT = 68;
 
 	/**
 	 * Equality method allowing for nulls
@@ -69,19 +70,9 @@ public static int refCount(ACell a) {
 	 * @param a Cell to check (may be null)
 	 * @return Number of Refs in the object.
 	 */
-	public static int branchCount(ACell a) {
-		if (a==null) return 0;
-		int n=a.getRefCount();
-		int bc=0;
-		for (int i=0; i<n; i++) {
-			Ref<?> ref=a.getRef(i);
-			if (ref.isEmbedded()) {
-				bc+=branchCount(ref.getValue());
-			} else {
-				bc++;
-			}
-		}
-		return bc;
+	public static int branchCount(ACell v) {
+		if (v==null) return 0;
+		return v.getBranchCount();
 	}
 
 	/**
@@ -93,7 +84,7 @@ public static int branchCount(ACell a) {
 	 * @return Ref for cell
 	 */
 	public static <R extends ACell> Ref<R> getRef(ACell cell, int index) {
-		if (cell ==null) throw new IndexOutOfBoundsException("Bad ref index called on null");
+		if (cell==null) throw new IndexOutOfBoundsException("getRef called on null");
 		return cell.getRef(index);
 	}
 

convex-core/src/main/java/convex/core/data/Ref.java

@@ -236,6 +236,16 @@ public Ref<T> withMinimumStatus(int newStatus) {
 	 * @return The value contained in this Ref
 	 */
 	public abstract T getValue();
+	
+	/**
+	 * Get the number of child branches from this Ref
+	 * @return Number of branches
+	 */
+	public int branchCount() {
+		ACell v=getValue();
+		if (v==null) return 0;
+		return v.getBranchCount();
+	}
 
 	@Override
 	public int hashCode() {

convex-core/src/main/java/convex/core/data/Refs.java

@@ -147,6 +147,9 @@ public static long uniqueRefCount(ACell a) {
 		Set<Ref<?>> rs=accumulateRefSet(a);
 		return rs.size();
 	}
+	
+
+
 
 	/**
 	 * Utility function to locate missing data

convex-core/src/test/java/convex/core/data/ObjectsTest.java

@@ -80,10 +80,31 @@ private static void doBranchTests(ACell a) {
 		assertTrue(bc>=0);
 		assertTrue(bc<=Cells.MAX_BRANCH_COUNT);
 
+		// out of range branches should be null
+		assertNull(a.getBranchRef(-1));
+		assertNull(a.getBranchRef(bc));
+		
+		// bc of zero equivalent to completely encoded
+		assertEquals(a.isCompletelyEncoded(),bc==0);
+		
+		int rc=a.getRefCount();
+		if (rc==0) {
+			// if no Refs, clearly none of them can be branches!
+			assertEquals(0,bc);
+		} else if (rc==1) {
+			Ref<?> cr=a.getRef(0);
+			if (cr.isEmbedded()) {
+				assertEquals(bc,cr.branchCount());
+			} else {
+				assertEquals(1,bc);
+			}
+		}
+		
 		if (bc==0) {
 			assertNull(a.getBranchRef(0));
 			Cells.visitBranches(a, v->fail("Shouldn't visit any branch!"));
 		} else {
+			// branch refs within range should be non-null
 			assertNotNull(a.getBranchRef(0));
 			assertNotNull(a.getBranchRef(bc-1));
 

convex-core/src/test/java/convex/core/data/VectorsTest.java

@@ -80,6 +80,31 @@ public void testChunks() {
 		AVector<CVMLong> v = Samples.INT_VECTOR_300.getChunk(0);
 		assertEquals(VectorTree.class, v.getChunk(0).concat(v).getClass());
 	}
+	
+	@Test
+	public void testMaxBranches() {
+		// non-embedded vector with 16 elements 
+		AVector<ACell> nonEmbed=Vectors.repeat(Samples.INT_VECTOR_10, 16);
+		assertFalse(nonEmbed.isEmbedded());
+		
+		// embedded tail with 4 branches, count 64
+		AVector<ACell> tail=nonEmbed.concat(nonEmbed).concat(nonEmbed).concat(nonEmbed);
+		assertEquals(4,tail.getBranchCount());
+		assertEquals(64,tail.count());
+		assertTrue(tail.isEmbedded());
+
+		
+		AVector<ACell> bigEmbed=Vectors.repeat(tail,16);
+		assertEquals(16,bigEmbed.getRefCount());
+		assertEquals(64,bigEmbed.getBranchCount()); // maximum for vector?
+		
+		AVector<ACell> v=tail.concat(bigEmbed);
+		assertFalse(v.isCompletelyEncoded());
+		
+		doVectorTests(nonEmbed);
+		doVectorTests(bigEmbed);
+		doVectorTests(v);
+	}
 
 	@Test
 	public void testChunkConcat() {