add api for detecting cell existence

* new API "has(TensorAddress)" detects if a Tensor has a cell with the given address.
* use new API in join and merge.  This will give different results for
  cells that are present but contain NaN versus cells that aren't present at all.
* use new API in slice. This gives a different default (0, not NaN) when trying to
  access cells that aren't present.

8 files changed, 54 insertions, 13 deletions

diff --git a/vespajlib/abi-spec.json b/vespajlib/abi-spec.json
index ebca0a4d852..ccdd09e4cab 100644
--- a/vespajlib/abi-spec.json
+++ b/vespajlib/abi-spec.json
@@ -891,6 +891,7 @@
       "public varargs double get(long[])",
       "public varargs float getFloat(long[])",
       "public double get(com.yahoo.tensor.TensorAddress)",
+      "public boolean has(com.yahoo.tensor.TensorAddress)",
       "public abstract double get(long)",
       "public abstract float getFloat(long)",
       "public com.yahoo.tensor.TensorType type()",
@@ -941,6 +942,7 @@
       "public com.yahoo.tensor.TensorType type()",
       "public long size()",
       "public double get(com.yahoo.tensor.TensorAddress)",
+      "public boolean has(com.yahoo.tensor.TensorAddress)",
       "public java.util.Iterator cellIterator()",
       "public java.util.Iterator valueIterator()",
       "public java.util.Map cells()",
@@ -1031,6 +1033,7 @@
       "public com.yahoo.tensor.TensorType type()",
       "public long size()",
       "public double get(com.yahoo.tensor.TensorAddress)",
+      "public boolean has(com.yahoo.tensor.TensorAddress)",
       "public java.util.Iterator cellIterator()",
       "public java.util.Iterator valueIterator()",
       "public java.util.Map cells()",
@@ -1151,6 +1154,7 @@
       "public boolean isEmpty()",
       "public abstract long size()",
       "public abstract double get(com.yahoo.tensor.TensorAddress)",
+      "public abstract boolean has(com.yahoo.tensor.TensorAddress)",
       "public abstract java.util.Iterator cellIterator()",
       "public abstract java.util.Iterator valueIterator()",
       "public abstract java.util.Map cells()",
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
index dfc26cf0282..67eace78c45 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java
@@ -118,6 +118,17 @@ public abstract class IndexedTensor implements Tensor {
         }
     }
 
+    @Override
+    public boolean has(TensorAddress address) {
+        try {
+            long index = toValueIndex(address, dimensionSizes, type);
+            if (index < 0) return false;
+            return (index < size());
+        } catch (IllegalArgumentException e) {
+            return false;
+        }
+    }
+
     /**
      * Returns the value at the given <i>standard value order</i> index as a double.
      *
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/MappedTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/MappedTensor.java
index 33f904efd42..9d04e10bacb 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/MappedTensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/MappedTensor.java
@@ -35,6 +35,9 @@ public class MappedTensor implements Tensor {
     public double get(TensorAddress address) { return cells.getOrDefault(address, Double.NaN); }
 
     @Override
+    public boolean has(TensorAddress address) { return cells.containsKey(address); }
+
+    @Override
     public Iterator<Cell> cellIterator() { return new CellIteratorAdaptor(cells.entrySet().iterator()); }
 
     @Override
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/MixedTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/MixedTensor.java
index 7631a2e4eab..e686a42d530 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/MixedTensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/MixedTensor.java
@@ -61,6 +61,17 @@ public class MixedTensor implements Tensor {
         return cell.getValue();
     }
 
+    @Override
+    public boolean has(TensorAddress address) {
+        long cellIndex = index.indexOf(address);
+        if (cellIndex < 0 || cellIndex >= cells.size())
+            return false;
+        Cell cell = cells.get((int)cellIndex);
+        if ( ! address.equals(cell.getKey()))
+            return false;
+        return true;
+    }
+
     /**
      * Returns an iterator over the cells of this tensor.
      * Cells are returned in order of increasing indexes in the
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
index 3378520dc91..8d014edd68f 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
@@ -70,6 +70,9 @@ public interface Tensor {
     /** Returns the value of a cell, or NaN if this cell does not exist/have no value */
     double get(TensorAddress address);
 
+    /** Returns true if this cell exists */
+    boolean has(TensorAddress address);
+
     /**
      * Returns the cell of this in some undefined order.
      * A cell instances is only valid until next() is called.
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 d43b7889982..0cbcfbb7ad6 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/Join.java
@@ -126,9 +126,10 @@ public class Join<NAMETYPE extends Name> extends PrimitiveTensorFunction<NAMETYP
         Tensor.Builder builder = Tensor.Builder.of(joinedType);
         for (Iterator<Tensor.Cell> i = a.cellIterator(); i.hasNext(); ) {
             Map.Entry<TensorAddress, Double> aCell = i.next();
-            double bCellValue = b.get(aCell.getKey());
-            if (Double.isNaN(bCellValue)) continue; // no match
-            builder.cell(aCell.getKey(), combinator.applyAsDouble(aCell.getValue(), bCellValue));
+            var key = aCell.getKey();
+            if (b.has(key)) {
+                builder.cell(key, combinator.applyAsDouble(aCell.getValue(), b.get(key)));
+            }
         }
         return builder.build();
     }
@@ -203,11 +204,12 @@ public class Join<NAMETYPE extends Name> extends PrimitiveTensorFunction<NAMETYP
         for (Iterator<Tensor.Cell> i = superspace.cellIterator(); i.hasNext(); ) {
             Map.Entry<TensorAddress, Double> supercell = i.next();
             TensorAddress subaddress = mapAddressToSubspace(supercell.getKey(), subspaceIndexes);
-            double subspaceValue = subspace.get(subaddress);
-            if ( ! Double.isNaN(subspaceValue))
+            if (subspace.has(subaddress)) {
+                double subspaceValue = subspace.get(subaddress);
                 builder.cell(supercell.getKey(),
                         reversedArgumentOrder ? combinator.applyAsDouble(supercell.getValue(), subspaceValue)
-                                : combinator.applyAsDouble(subspaceValue, supercell.getValue()));
+                             : combinator.applyAsDouble(subspaceValue, supercell.getValue()));
+            }
         }
         return builder.build();
     }
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/Merge.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/Merge.java
index 4aa09f3f4e3..a2387affa67 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/Merge.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/Merge.java
@@ -125,11 +125,12 @@ public class Merge<NAMETYPE extends Name> extends PrimitiveTensorFunction<NAMETY
     private static void addCellsOf(Tensor a, Tensor b, Tensor.Builder builder, DoubleBinaryOperator combinator) {
         for (Iterator<Tensor.Cell> i = a.cellIterator(); i.hasNext(); ) {
             Map.Entry<TensorAddress, Double> aCell = i.next();
-            double bCellValue = b.get(aCell.getKey());
-            if (Double.isNaN(bCellValue))
-                builder.cell(aCell.getKey(), aCell.getValue());
-            else if (combinator != null)
-                builder.cell(aCell.getKey(), combinator.applyAsDouble(aCell.getValue(), bCellValue));
+            var key = aCell.getKey();
+            if (! b.has(key)) {
+                builder.cell(key, aCell.getValue());
+            } else if (combinator != null) {
+                builder.cell(key, combinator.applyAsDouble(aCell.getValue(), b.get(key)));
+            }
         }
     }
 
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java
index 607c9a0ab44..da24aef50bc 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java
@@ -63,8 +63,14 @@ public class Slice<NAMETYPE extends Name> extends PrimitiveTensorFunction<NAMETY
         TensorType resultType = resultType(tensor.type());
 
         PartialAddress subspaceAddress = subspaceToAddress(tensor.type(), context);
-        if (resultType.rank() == 0) // shortcut common case
-            return Tensor.from(tensor.get(subspaceAddress.asAddress(tensor.type())));
+        if (resultType.rank() == 0) { // shortcut common case
+            var key = subspaceAddress.asAddress(tensor.type());
+            if (tensor.has(key)) {
+                return Tensor.from(tensor.get(key));
+            } else {
+                return Tensor.from(0.0);
+            }
+        }
 
         Tensor.Builder b = Tensor.Builder.of(resultType);
         for (Iterator<Tensor.Cell> i = tensor.cellIterator(); i.hasNext(); ) {