Use MappedTensor to represent tensor with no dimensions or values

10 files changed, 44 insertions, 43 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
index 4654f53647f..deee4aa02b6 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
@@ -103,7 +103,6 @@ public class IndexedTensor implements Tensor {
      * @throws IndexOutOfBoundsException if any of the indexes are out of bound or a wrong number of indexes are given
      */
     public double get(int ... indexes) {
-        if (values.length == 0) return Double.NaN;
         return values[toValueIndex(indexes, dimensionSizes)];
     }
 
@@ -157,7 +156,7 @@ public class IndexedTensor implements Tensor {
     @Override
     public Map<TensorAddress, Double> cells() {
         if (dimensionSizes.dimensions() == 0)
-            return values.length == 0 ? Collections.emptyMap() : Collections.singletonMap(TensorAddress.empty, values[0]);
+            return Collections.singletonMap(TensorAddress.empty, values[0]);
         
         ImmutableMap.Builder<TensorAddress, Double> builder = new ImmutableMap.Builder<>();
         Indexes indexes = Indexes.of(dimensionSizes, dimensionSizes, values.length);
@@ -221,7 +220,7 @@ public class IndexedTensor implements Tensor {
         public TensorType type() { return type; }
 
         @Override
-        public abstract IndexedTensor build();
+        public abstract Tensor build();
 
     }
     
@@ -269,11 +268,14 @@ public class IndexedTensor implements Tensor {
         }
 
         @Override
-        public IndexedTensor build() {
+        public Tensor build() {
             // Note that we do not check for no NaN's here for performance reasons. 
             // NaN's don't get lost so leaving them in place should be quite benign 
-            if (values.length == 1 && Double.isNaN(values[0]))
-                values = new double[0];
+
+            // An empty tensor with no dimensions is mapped
+            if (values.length == 1 && Double.isNaN(values[0]) && type.dimensions().isEmpty())
+                return MappedTensor.Builder.of(type).build();
+
             IndexedTensor tensor = new IndexedTensor(type, sizes, values);
             // prevent further modification
             sizes = null;
@@ -316,24 +318,28 @@ public class IndexedTensor implements Tensor {
         }
 
         @Override
-        public IndexedTensor build() {
-            if (firstDimension == null) // empty
-                return new IndexedTensor(type, new DimensionSizes.Builder(type.dimensions().size()).build(), new double[] {});
+        public Tensor build() {
+            if (firstDimension == null && type.dimensions().isEmpty()) // empty
+                return MappedTensor.Builder.of(type).build();
             if (type.dimensions().isEmpty()) // single number
                 return new IndexedTensor(type, new DimensionSizes.Builder(type.dimensions().size()).build(), new double[] {(Double) firstDimension.get(0) });
 
             DimensionSizes dimensionSizes = findDimensionSizes(firstDimension);
             double[] values = new double[dimensionSizes.totalSize()];
-            fillValues(0, 0, firstDimension, dimensionSizes, values);
+            if (firstDimension != null)
+                fillValues(0, 0, firstDimension, dimensionSizes, values);
             return new IndexedTensor(type, dimensionSizes, values);
         }
         
         private DimensionSizes findDimensionSizes(List<Object> firstDimension) {
             List<Integer> dimensionSizeList = new ArrayList<>(type.dimensions().size());
-            findDimensionSizes(0, dimensionSizeList, firstDimension);
+            if (firstDimension != null)
+                findDimensionSizes(0, dimensionSizeList, firstDimension);
             DimensionSizes.Builder b = new DimensionSizes.Builder(type.dimensions().size()); // may be longer than the list but that's correct
-            for (int i = 0; i < b.dimensions(); i++)
-                b.set(i, dimensionSizeList.get(i));
+            for (int i = 0; i < b.dimensions(); i++) {
+                if (i < dimensionSizeList.size())
+                    b.set(i, dimensionSizeList.get(i));
+            }
             return b.build();
         }
 
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
index 51d40a89f3b..29c508ce12f 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
@@ -213,10 +213,9 @@ public interface Tensor {
 
     static String contentToString(Tensor tensor) {
         List<java.util.Map.Entry<TensorAddress, Double>> cellEntries = new ArrayList<>(tensor.cells().entrySet());
-        if (tensor.type().dimensions().isEmpty()) { // TODO: Decide on one way to represent degeneration to number
+        if (tensor.type().dimensions().isEmpty()) {
             if (cellEntries.isEmpty()) return "{}";
-            double value = cellEntries.get(0).getValue();
-            return value == 0.0 ? "{}" : "{" + value +"}";
+            return "{" + cellEntries.get(0).getValue() +"}";
         }
         
         Collections.sort(cellEntries, java.util.Map.Entry.<TensorAddress, Double>comparingByKey());
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/TensorType.java b/vespajlib/src/main/java/com/yahoo/tensor/TensorType.java
index 82f36972a47..fbc469c1829 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/TensorType.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/TensorType.java
@@ -53,9 +53,6 @@ public class TensorType {
         return TensorTypeParser.fromSpec(specString);
     }
 
-    /** Returns true if all dimensions of this are indexed */
-    public boolean isIndexed() { return dimensions().stream().allMatch(d -> d.isIndexed()); }
-    
     /** Returns an immutable list of the dimensions of this */
     public List<Dimension> dimensions() { return dimensions; }
     
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java
index ceade39ce42..f295e129a0f 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java
@@ -113,7 +113,7 @@ public class Join extends PrimitiveTensorFunction {
     
     /** Join a tensor into a superspace */
     private Tensor subspaceJoin(Tensor subspace, Tensor superspace, TensorType joinedType, boolean reversedArgumentOrder) {
-        if (subspace.type().isIndexed() && superspace.type().isIndexed())
+        if (subspace instanceof IndexedTensor && superspace instanceof IndexedTensor)
             return indexedSubspaceJoin((IndexedTensor) subspace, (IndexedTensor) superspace, joinedType, reversedArgumentOrder);
         else
             return generalSubspaceJoin(subspace, superspace, joinedType, reversedArgumentOrder);
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/serialization/DenseBinaryFormat.java b/vespajlib/src/main/java/com/yahoo/tensor/serialization/DenseBinaryFormat.java
index c3284131be0..0a97576d5b7 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/serialization/DenseBinaryFormat.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/serialization/DenseBinaryFormat.java
@@ -41,13 +41,8 @@ public class DenseBinaryFormat implements BinaryFormat {
 
     private void encodeCells(GrowableByteBuffer buffer, Tensor tensor) {
         Iterator<Double> i = tensor.valueIterator();
-        if ( ! i.hasNext()) { // no values: Encode as NaN, as 0 dimensions may also mean 1 value
-            buffer.putDouble(Double.NaN);
-        }
-        else {
-            while (i.hasNext())
-                buffer.putDouble(i.next());
-        }
+        while (i.hasNext())
+            buffer.putDouble(i.next());
     }
 
     @Override
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/IndexedTensorTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/IndexedTensorTestCase.java
index 3f7f02c6c00..01d1e6fc602 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/IndexedTensorTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/IndexedTensorTestCase.java
@@ -21,19 +21,6 @@ public class IndexedTensorTestCase {
     private final int zSize = 5;
 
     @Test
-    public void testEmpty() {
-        Tensor empty = Tensor.Builder.of(TensorType.empty).build();
-        assertTrue(empty instanceof IndexedTensor);
-        assertTrue(empty.isEmpty());
-        assertEquals("{}", empty.toString());
-        Tensor emptyFromString = Tensor.from(TensorType.empty, "{}");
-        assertEquals("{}", Tensor.from(TensorType.empty, "{}").toString());
-        assertTrue(emptyFromString.isEmpty());
-        assertTrue(emptyFromString instanceof IndexedTensor);
-        assertEquals(empty, emptyFromString);
-    }
-    
-    @Test
     public void testSingleValue() {
         Tensor singleValue = Tensor.Builder.of(TensorType.empty).cell(TensorAddress.empty, 3.5).build();
         assertTrue(singleValue instanceof IndexedTensor);
@@ -91,7 +78,7 @@ public class IndexedTensorTestCase {
                         for (int z = 0; z < zSize; z++)
                             builder.cell(value(v, w, x, y, z), v, w, x, y, z);
 
-        IndexedTensor tensor = builder.build();
+        IndexedTensor tensor = (IndexedTensor)builder.build();
 
         // Lookup by index arguments
         for (int v = 0; v < vSize; v++)
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/MappedTensorTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/MappedTensorTestCase.java
index 4c32a80dc11..a2df146c8e1 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/MappedTensorTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/MappedTensorTestCase.java
@@ -2,6 +2,7 @@
 package com.yahoo.tensor;
 
 import com.google.common.collect.Sets;
+import junit.framework.TestCase;
 import org.junit.Test;
 
 import java.util.Set;
@@ -18,6 +19,19 @@ import static org.junit.Assert.fail;
 public class MappedTensorTestCase {
 
     @Test
+    public void testEmpty() {
+        Tensor empty = Tensor.Builder.of(TensorType.empty).build();
+        TestCase.assertTrue(empty instanceof MappedTensor);
+        TestCase.assertTrue(empty.isEmpty());
+        assertEquals("{}", empty.toString());
+        Tensor emptyFromString = Tensor.from(TensorType.empty, "{}");
+        assertEquals("{}", Tensor.from(TensorType.empty, "{}").toString());
+        TestCase.assertTrue(emptyFromString.isEmpty());
+        TestCase.assertTrue(emptyFromString instanceof MappedTensor);
+        assertEquals(empty, emptyFromString);
+    }
+
+    @Test
     public void testOneDimensionalBuilding() {
         TensorType type = new TensorType.Builder().mapped("x").build();
         Tensor tensor = Tensor.Builder.of(type).
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/TensorTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/TensorTestCase.java
index feeba1a7a10..e649d3cde2a 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/TensorTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/TensorTestCase.java
@@ -21,7 +21,7 @@ import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 /**
- * Tests Tensor functionality
+ * Tests tensor functionality
  * 
  * @author bratseth
  */
@@ -30,6 +30,9 @@ public class TensorTestCase {
     @Test
     public void testStringForm() {
         assertEquals("{}", Tensor.from("{}").toString());
+        assertTrue(Tensor.from("{}") instanceof MappedTensor);
+        assertEquals("{5.7}", Tensor.from("{5.7}").toString());
+        assertTrue(Tensor.from("{5.7}") instanceof IndexedTensor);
         assertEquals("{{d1:l1,d2:l1}:5.0,{d1:l1,d2:l2}:6.0}", Tensor.from("{ {d1:l1,d2:l1}: 5,   {d2:l2, d1:l1}:6.0} ").toString());
         assertEquals("{{d1:l1,d2:l1}:-5.3,{d1:l1,d2:l2}:0.0}", Tensor.from("{ {d1:l1,d2:l1}:-5.3, {d2:l2, d1:l1}:0}").toString());
     }
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/serialization/DenseBinaryFormatTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/serialization/DenseBinaryFormatTestCase.java
index 697eb2a7329..d2b2044f3ed 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/serialization/DenseBinaryFormatTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/serialization/DenseBinaryFormatTestCase.java
@@ -20,7 +20,6 @@ public class DenseBinaryFormatTestCase {
 
     @Test
     public void testSerialization() {
-        assertSerialization("{}");
         assertSerialization("{-5.37}");
         assertSerialization("tensor(x[]):{{x:0}:2.0}");
         assertSerialization("tensor(x[],y[]):{{x:0,y:0}:2.0}");
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/serialization/SparseBinaryFormatTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/serialization/SparseBinaryFormatTestCase.java
index b314fe06f08..283aa90cf65 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/serialization/SparseBinaryFormatTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/serialization/SparseBinaryFormatTestCase.java
@@ -19,6 +19,7 @@ public class SparseBinaryFormatTestCase {
 
     @Test
     public void testSerialization() {
+        assertSerialization("tensor(x{}):{}");
         assertSerialization("tensor(x{}):{{x:0}:2.0}");
         assertSerialization("tensor(dimX{},dimY{}):{{dimX:labelA,dimY:labelB}:2.0,{dimY:labelC,dimX:labelD}:3.0}");
         assertSerialization("tensor(x{},y{}):{{x:0,y:1}:2.0}");