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.

1 files changed, 11 insertions, 0 deletions

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.
      *