Merge pull request #9641 from vespa-engine/bratseth/ranking-expression-models

Bratseth/ranking expression models

4 files changed, 33 insertions, 4 deletions

diff --git a/vespajlib/abi-spec.json b/vespajlib/abi-spec.json
index 9264b0a8255..04e68e60178 100644
--- a/vespajlib/abi-spec.json
+++ b/vespajlib/abi-spec.json
@@ -1180,7 +1180,8 @@
       "public static boolean approxEquals(double, double)",
       "public static com.yahoo.tensor.Tensor from(com.yahoo.tensor.TensorType, java.lang.String)",
       "public static com.yahoo.tensor.Tensor from(java.lang.String, java.lang.String)",
-      "public static com.yahoo.tensor.Tensor from(java.lang.String)"
+      "public static com.yahoo.tensor.Tensor from(java.lang.String)",
+      "public static com.yahoo.tensor.Tensor from(double)"
     ],
     "fields": []
   },
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
index ebb341147cf..22ff793e6fa 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/Tensor.java
@@ -367,6 +367,13 @@ public interface Tensor {
         return TensorParser.tensorFrom(tensorString, Optional.empty());
     }
 
+    /**
+     * Returns a double as a tensor: A dimensionless tensor containing the value as its cell
+     */
+    static Tensor from(double value) {
+        return Tensor.Builder.of(TensorType.empty).cell(value).build();
+    }
+
     class Cell implements Map.Entry<TensorAddress, Double> {
 
         private final TensorAddress address;
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java b/vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java
index 3213982355b..6382361f187 100644
--- a/vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java
+++ b/vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java
@@ -1,7 +1,11 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.tensor.serialization;
 
+import com.yahoo.slime.ArrayTraverser;
 import com.yahoo.slime.Cursor;
+import com.yahoo.slime.Inspector;
+import com.yahoo.slime.JsonDecoder;
+import com.yahoo.slime.ObjectTraverser;
 import com.yahoo.slime.Slime;
 import com.yahoo.tensor.Tensor;
 import com.yahoo.tensor.TensorAddress;
@@ -17,9 +21,7 @@ import java.util.Iterator;
 // TODO: We should probably move reading of this format from the document module to here
 public class JsonFormat {
 
-    /**
-     * Serialize the given tensor into JSON format
-     */
+    /** Serializes the given tensor into JSON format */
     public static byte[] encode(Tensor tensor) {
         Slime slime = new Slime();
         Cursor root = slime.setObject();
@@ -38,4 +40,19 @@ public class JsonFormat {
             addressObject.setString(type.dimensions().get(i).name(), address.label(i));
     }
 
+    /** Deserializes the given tensor from JSON format */
+    // TODO: Add explicit validation (valid() checks) below
+    public static Tensor decode(TensorType type, byte[] jsonTensorValue) {
+        Tensor.Builder tensorBuilder = Tensor.Builder.of(type);
+        Inspector root = new JsonDecoder().decode(new Slime(), jsonTensorValue).get();
+        Inspector cells = root.field("cells");
+        cells.traverse((ArrayTraverser) (__, cell) -> decodeCell(cell, tensorBuilder.cell()));
+        return tensorBuilder.build();
+    }
+
+    private static void decodeCell(Inspector cell, Tensor.Builder.CellBuilder cellBuilder) {
+        cell.field("address").traverse((ObjectTraverser) (dimension, label) -> cellBuilder.label(dimension, label.asString()));
+        cellBuilder.value(cell.field("value").asDouble());
+    }
+
 }
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/serialization/JsonFormatTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/serialization/JsonFormatTestCase.java
index 16af413f2f0..5a025b6eb96 100644
--- a/vespajlib/src/test/java/com/yahoo/tensor/serialization/JsonFormatTestCase.java
+++ b/vespajlib/src/test/java/com/yahoo/tensor/serialization/JsonFormatTestCase.java
@@ -26,6 +26,8 @@ public class JsonFormatTestCase {
                      "{\"address\":{\"x\":\"c\",\"y\":\"d\"},\"value\":3.0}" +
                      "]}",
                      new String(json, StandardCharsets.UTF_8));
+        Tensor decoded = JsonFormat.decode(tensor.type(), json);
+        assertEquals(tensor, decoded);
     }
 
     @Test
@@ -44,6 +46,8 @@ public class JsonFormatTestCase {
                      "{\"address\":{\"x\":\"1\",\"y\":\"1\"},\"value\":7.0}" +
                      "]}",
                      new String(json, StandardCharsets.UTF_8));
+        Tensor decoded = JsonFormat.decode(tensor.type(), json);
+        assertEquals(tensor, decoded);
     }
 
 }