1 files changed, 146 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java
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index 00000000000..9ce2496c65b
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+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/DynamicTensor.java
@@ -0,0 +1,146 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.tensor.functions;
+
+import com.google.common.collect.ImmutableMap;
+import com.yahoo.tensor.IndexedTensor;
+import com.yahoo.tensor.Tensor;
+import com.yahoo.tensor.TensorAddress;
+import com.yahoo.tensor.TensorType;
+import com.yahoo.tensor.evaluation.EvaluationContext;
+import com.yahoo.tensor.evaluation.TypeContext;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+/**
+ * A function which is a tensor whose values are computed by individual lambda functions on evaluation.
+ *
+ * @author bratseth
+ */
+public abstract class DynamicTensor extends PrimitiveTensorFunction {
+
+    private final TensorType type;
+
+    DynamicTensor(TensorType type) {
+        this.type = type;
+    }
+
+    @Override
+    public <NAMETYPE extends TypeContext.Name> TensorType type(TypeContext<NAMETYPE> context) { return type; }
+
+    @Override
+    public List<TensorFunction> arguments() { return Collections.emptyList(); }
+
+    @Override
+    public TensorFunction withArguments(List<TensorFunction> arguments) {
+        if (arguments.size() != 0)
+            throw new IllegalArgumentException("Dynamic tensors must have 0 arguments, got " + arguments.size());
+        return this;
+    }
+
+    @Override
+    public PrimitiveTensorFunction toPrimitive() { return this; }
+
+    TensorType type() { return type; }
+
+    /** Creates a dynamic tensor function. The cell addresses must match the type. */
+    public static DynamicTensor from(TensorType type, Map<TensorAddress, Function<EvaluationContext<?> , Double>> cells) {
+        return new MappedDynamicTensor(type, cells);
+    }
+
+    /** Creates a dynamic tensor function for a bound, indexed tensor */
+    public static DynamicTensor from(TensorType type, List<Function<EvaluationContext<?> , Double>> cells) {
+        return new IndexedDynamicTensor(type, cells);
+    }
+
+    private static class MappedDynamicTensor extends DynamicTensor {
+
+        private final ImmutableMap<TensorAddress, Function<EvaluationContext<?> , Double>> cells;
+
+        MappedDynamicTensor(TensorType type, Map<TensorAddress, Function<EvaluationContext<?> , Double>> cells) {
+            super(type);
+            this.cells = ImmutableMap.copyOf(cells);
+        }
+
+        @Override
+        public <NAMETYPE extends TypeContext.Name> Tensor evaluate(EvaluationContext<NAMETYPE> context) {
+            Tensor.Builder builder = Tensor.Builder.of(type());
+            for (var cell : cells.entrySet())
+                builder.cell(cell.getKey(), cell.getValue().apply(context));
+            return builder.build();
+        }
+
+        @Override
+        public String toString(ToStringContext context) {
+            return type().toString() + ":" + contentToString();
+        }
+
+        private String contentToString() {
+            if (type().dimensions().isEmpty()) {
+                if (cells.isEmpty()) return "{}";
+                return "{" + cells.values().iterator().next() + "}";
+            }
+
+            StringBuilder b = new StringBuilder("{");
+            for (var cell : cells.entrySet()) {
+                b.append(cell.getKey().toString(type())).append(":").append(cell.getValue());
+                b.append(",");
+            }
+            if (b.length() > 1)
+                b.setLength(b.length() - 1);
+            b.append("}");
+
+            return b.toString();
+        }
+
+    }
+
+    private static class IndexedDynamicTensor extends DynamicTensor {
+
+        private final List<Function<EvaluationContext<?>, Double>> cells;
+
+        IndexedDynamicTensor(TensorType type, List<Function<EvaluationContext<?> , Double>> cells) {
+            super(type);
+            if ( ! type.dimensions().stream().allMatch(d -> d.type() == TensorType.Dimension.Type.indexedBound))
+                throw new IllegalArgumentException("A dynamic tensor can only be created from a list if the type has " +
+                                                   "only indexed, bound dimensions, but this has " + type);
+            this.cells = List.copyOf(cells);
+        }
+
+        @Override
+        public <NAMETYPE extends TypeContext.Name> Tensor evaluate(EvaluationContext<NAMETYPE> context) {
+            IndexedTensor.BoundBuilder builder = (IndexedTensor.BoundBuilder)Tensor.Builder.of(type());
+            for (int i = 0; i < cells.size(); i++)
+                builder.cellByDirectIndex(i, cells.get(i).apply(context));
+            return builder.build();
+        }
+
+        @Override
+        public String toString(ToStringContext context) {
+            return type().toString() + ":" + contentToString();
+        }
+
+        private String contentToString() {
+            if (type().dimensions().isEmpty()) {
+                if (cells.isEmpty()) return "{}";
+                return "{" + cells.get(0) + "}";
+            }
+
+            StringBuilder b = new StringBuilder("[");
+            for (var cell : cells) {
+                b.append(cell);
+                b.append(",");
+            }
+            if (b.length() > 1)
+                b.setLength(b.length() - 1);
+            b.append("]");
+
+            return b.toString();
+        }
+
+    }
+
+}