feat: add support for map:size function

Author: EPMatt

src/main/java/org/rumbledb/context/BuiltinFunctionCatalogue.java

@@ -96,6 +96,7 @@
 import org.rumbledb.runtime.functions.maps.MapGetFunctionIterator;
 import org.rumbledb.runtime.functions.maps.MapEntryFunctionIterator;
 import org.rumbledb.runtime.functions.maps.MapKeysFunctionIterator;
+import org.rumbledb.runtime.functions.maps.MapSizeFunctionIterator;
 import org.rumbledb.runtime.functions.object.ObjectAccumulateFunctionIterator;
 import org.rumbledb.runtime.functions.object.ObjectDescendantFunctionIterator;
 import org.rumbledb.runtime.functions.object.ObjectDescendantPairsFunctionIterator;
@@ -2786,6 +2787,21 @@ private static BuiltinFunction createBuiltinFunction(
         MapKeysFunctionIterator.class,
         BuiltinFunction.BuiltinFunctionExecutionMode.LOCAL
     );
+
+    /**
+     * W3C map:size — F&O 3.1: map:size($map as map(*)) as xs:integer.
+     */
+    static final BuiltinFunction map_size = createBuiltinFunction(
+        new Name(
+                Name.MAP_NS,
+                "map",
+                "size"
+        ),
+        "map",
+        "integer",
+        MapSizeFunctionIterator.class,
+        BuiltinFunction.BuiltinFunctionExecutionMode.LOCAL
+    );
     /**
      * function that returns the JSON null
      */
@@ -3769,8 +3785,9 @@ private static BuiltinFunction createBuiltinFunction(
         builtinFunctions.put(keys.getIdentifier(), keys);
         builtinFunctions.put(members.getIdentifier(), members);
         builtinFunctions.put(map_get.getIdentifier(), map_get);
-    builtinFunctions.put(map_entry.getIdentifier(), map_entry);
+        builtinFunctions.put(map_entry.getIdentifier(), map_entry);
         builtinFunctions.put(map_keys.getIdentifier(), map_keys);
+        builtinFunctions.put(map_size.getIdentifier(), map_size);
         builtinFunctions.put(null_function.getIdentifier(), null_function);
         builtinFunctions.put(size.getIdentifier(), size);
         builtinFunctions.put(array_size.getIdentifier(), array_size);

src/main/java/org/rumbledb/runtime/functions/maps/MapEntryFunctionIterator.java

@@ -17,9 +17,9 @@
 /**
  * W3C XPath/XQuery {@code map:entry}:
  * <ul>
- *   <li>atomizes a single key into exactly one atomic value</li>
- *   <li>materializes the value into a general sequence (possibly empty)</li>
- *   <li>returns a map containing a single key/value binding</li>
+ * <li>atomizes a single key into exactly one atomic value</li>
+ * <li>materializes the value into a general sequence (possibly empty)</li>
+ * <li>returns a map containing a single key/value binding</li>
  * </ul>
  */
 public class MapEntryFunctionIterator extends AtMostOneItemLocalRuntimeIterator {
@@ -79,12 +79,13 @@ public Item materializeFirstItemOrNull(DynamicContext dynamicContext) {
         List<Item> valueSequence = new ArrayList<>();
         this.valueIterator.materialize(dynamicContext, valueSequence);
 
-        return ItemFactory.getInstance().createMapItem(
+        return ItemFactory.getInstance()
+            .createMapItem(
                 Collections.singletonList(key),
                 Collections.singletonList(valueSequence),
                 getMetadata(),
                 false
-        );
+            );
     }
 }
 

src/main/java/org/rumbledb/runtime/functions/maps/MapSizeFunctionIterator.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.rumbledb.runtime.functions.maps;
+
+import org.rumbledb.api.Item;
+import org.rumbledb.context.DynamicContext;
+import org.rumbledb.context.RuntimeStaticContext;
+import org.rumbledb.items.ItemFactory;
+import org.rumbledb.runtime.AtMostOneItemLocalRuntimeIterator;
+import org.rumbledb.runtime.RuntimeIterator;
+
+import java.util.List;
+
+/**
+ * W3C map:size function.
+ */
+public class MapSizeFunctionIterator extends AtMostOneItemLocalRuntimeIterator {
+
+    private static final long serialVersionUID = 1L;
+
+    public MapSizeFunctionIterator(
+            List<RuntimeIterator> arguments,
+            RuntimeStaticContext staticContext
+    ) {
+        super(arguments, staticContext);
+    }
+
+    @Override
+    public Item materializeFirstItemOrNull(DynamicContext context) {
+        Item map = this.children.get(0).materializeFirstItemOrNull(context);
+        if (map == null) {
+            return null;
+        }
+        return ItemFactory.getInstance().createIntItem(map.getItemKeys().size());
+    }
+}
+