From 494f5d0e133417880881b05c4fe4f08a265a7510 Mon Sep 17 00:00:00 2001
From: Arne Juul <arnej@yahooinc.com>
Date: Mon, 20 Mar 2023 10:41:16 +0000
Subject: add withTransformedFunctions() to TensorFunction API

---
 vespajlib/abi-spec.json                            |  4 +++-
 .../com/yahoo/tensor/functions/DynamicTensor.java  | 24 ++++++++++++++++++++++
 .../java/com/yahoo/tensor/functions/Slice.java     | 17 +++++++++++++++
 .../com/yahoo/tensor/functions/TensorFunction.java |  6 ++++++
 4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/vespajlib/abi-spec.json b/vespajlib/abi-spec.json
index e45b13a6eb0..88872fef8a1 100644
--- a/vespajlib/abi-spec.json
+++ b/vespajlib/abi-spec.json
@@ -2765,6 +2765,7 @@
       "public void <init>(com.yahoo.tensor.functions.TensorFunction, java.util.List)",
       "public java.util.List arguments()",
       "public java.util.List selectorFunctions()",
+      "public com.yahoo.tensor.functions.TensorFunction withTransformedFunctions(java.util.function.Function)",
       "public com.yahoo.tensor.functions.Slice withArguments(java.util.List)",
       "public com.yahoo.tensor.functions.PrimitiveTensorFunction toPrimitive()",
       "public com.yahoo.tensor.Tensor evaluate(com.yahoo.tensor.evaluation.EvaluationContext)",
@@ -2810,7 +2811,8 @@
       "public abstract java.lang.String toString(com.yahoo.tensor.functions.ToStringContext)",
       "public java.util.Optional asScalarFunction()",
       "public java.lang.String toString()",
-      "public abstract int hashCode()"
+      "public abstract int hashCode()",
+      "public com.yahoo.tensor.functions.TensorFunction withTransformedFunctions(java.util.function.Function)"
     ],
     "fields" : [ ]
   },
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java
index 61d3acf6338..630eeb81d13 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java
@@ -12,8 +12,10 @@ import com.yahoo.tensor.evaluation.TypeContext;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Objects;
+import java.util.function.Function;
 
 /**
  * A function which is a tensor whose values are computed by individual lambda functions on evaluation.
@@ -82,6 +84,17 @@ public abstract class DynamicTensor<NAMETYPE extends Name> extends PrimitiveTens
             return result;
         }
 
+        public TensorFunction<NAMETYPE> withTransformedFunctions(
+                Function<ScalarFunction<NAMETYPE>, ScalarFunction<NAMETYPE>> transformer)
+        {
+            Map<TensorAddress, ScalarFunction<NAMETYPE>> transformedCells = new LinkedHashMap<>();
+            for (var orig : cells.entrySet()) {
+                var transformed = transformer.apply(orig.getValue());
+                transformedCells.put(orig.getKey(), transformed);
+            }
+            return new MappedDynamicTensor<>(type(), transformedCells);
+        }
+
         @Override
         public Tensor evaluate(EvaluationContext<NAMETYPE> context) {
             Tensor.Builder builder = Tensor.Builder.of(type());
@@ -134,6 +147,17 @@ public abstract class DynamicTensor<NAMETYPE extends Name> extends PrimitiveTens
             return result;
         }
 
+        public TensorFunction<NAMETYPE> withTransformedFunctions(
+                Function<ScalarFunction<NAMETYPE>, ScalarFunction<NAMETYPE>> transformer)
+        {
+            List<ScalarFunction<NAMETYPE>> transformedCells = new ArrayList<>();
+            for (var orig : cells) {
+                var transformed = transformer.apply(orig);
+                transformedCells.add(transformed);
+            }
+            return new IndexedDynamicTensor<>(type(), transformedCells);
+        }
+
         @Override
         public Tensor evaluate(EvaluationContext<NAMETYPE> context) {
             IndexedTensor.BoundBuilder builder = (IndexedTensor.BoundBuilder)Tensor.Builder.of(type());
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 87e24306031..066d75bcd9c 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/Slice.java
@@ -16,6 +16,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -56,6 +57,22 @@ public class Slice<NAMETYPE extends Name> extends PrimitiveTensorFunction<NAMETY
         return result;
     }
 
+    public TensorFunction<NAMETYPE> withTransformedFunctions(
+            Function<ScalarFunction<NAMETYPE>, ScalarFunction<NAMETYPE>> transformer)
+    {
+        List<DimensionValue<NAMETYPE>> transformedAddress = new ArrayList<>();
+        for (var orig : subspaceAddress) {
+            var idxFun = orig.index();
+            if (idxFun.isPresent()) {
+                var transformed = transformer.apply(idxFun.get());
+                transformedAddress.add(new DimensionValue<NAMETYPE>(orig.dimension(), transformed));
+            } else {
+                transformedAddress.add(orig);
+            }
+        }
+        return new Slice<>(argument, transformedAddress);
+    }
+
     @Override
     public Slice<NAMETYPE> withArguments(List<TensorFunction<NAMETYPE>> arguments) {
         if (arguments.size() != 1)
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/TensorFunction.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/TensorFunction.java
index 503f414d8eb..bf5eaeb6c2e 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/functions/TensorFunction.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/TensorFunction.java
@@ -10,6 +10,7 @@ import com.yahoo.tensor.evaluation.TypeContext;
 
 import java.util.List;
 import java.util.Optional;
+import java.util.function.Function;
 
 /**
  * A representation of a tensor function which is able to be translated to a set of primitive
@@ -72,4 +73,9 @@ public abstract class TensorFunction<NAMETYPE extends Name> {
     @Override
     public abstract int hashCode();
 
+    public TensorFunction<NAMETYPE> withTransformedFunctions(
+            Function<ScalarFunction<NAMETYPE>, ScalarFunction<NAMETYPE>> transformer)
+    {
+        return this;
+    }
 }
-- 
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