Consistent hashing and equal methods

src/main/java/org/rumbledb/items/AbstractArrayItem.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.items;
+
+import java.io.Serial;
+import java.util.List;
+
+import org.rumbledb.api.Item;
+
+/**
+ * Structural Java equality for both JSON arrays and XDM sequence-member arrays.
+ */
+public abstract class AbstractArrayItem implements Item {
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public final boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (!(other instanceof Item otherItem) || !otherItem.isArray()) {
+            return false;
+        }
+        return this.getSequenceMembers().equals(otherItem.getSequenceMembers());
+    }
+
+    @Override
+    public final int hashCode() {
+        int result = 1;
+        for (List<Item> member : this.getSequenceMembers()) {
+            result = 31 * result + member.hashCode();
+        }
+        return result;
+    }
+}

src/main/java/org/rumbledb/items/AbstractAtomicItem.java

@@ -0,0 +1,40 @@
+/*
+ * 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.items;
+
+import org.rumbledb.api.Item;
+
+import java.io.Serial;
+
+/**
+ * Base class that gives every atomic item one Java equality and hashing contract.
+ */
+public abstract class AbstractAtomicItem implements Item {
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public final boolean equals(Object other) {
+        return other instanceof Item item && AtomicItemEquivalence.equivalent(this, item);
+    }
+
+    @Override
+    public final int hashCode() {
+        return AtomicItemEquivalence.hash(this);
+    }
+}

src/main/java/org/rumbledb/items/AbstractMapItem.java

@@ -0,0 +1,58 @@
+/*
+ * 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.items;
+
+import java.io.Serial;
+import java.util.List;
+
+import org.rumbledb.api.Item;
+
+/**
+ * Order-independent structural Java equality for every materialized and lazy map representation.
+ */
+public abstract class AbstractMapItem implements Item {
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public final boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (!(other instanceof Item otherItem) || !otherItem.isMap() || this.getSize() != otherItem.getSize()) {
+            return false;
+        }
+        for (Item key : this.getItemKeys()) {
+            List<Item> value = this.getSequenceByKey(key);
+            List<Item> otherValue = otherItem.getSequenceByKey(key);
+            if (!value.equals(otherValue)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public final int hashCode() {
+        int result = this.getSize();
+        for (Item key : this.getItemKeys()) {
+            result += 31 * key.hashCode() + this.getSequenceByKey(key).hashCode();
+        }
+        return result;
+    }
+}

src/main/java/org/rumbledb/items/AnnotatedItem.java

@@ -9,7 +9,6 @@
 import java.time.Period;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 
 import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.ml.Estimator;
@@ -19,14 +18,11 @@
 import org.rumbledb.context.FunctionIdentifier;
 import org.rumbledb.context.Name;
 import org.rumbledb.exceptions.DuplicateObjectKeyException;
-import org.rumbledb.exceptions.ExceptionMetadata;
 import org.rumbledb.exceptions.OurBadException;
-import org.rumbledb.expressions.comparison.ComparisonExpression.ComparisonOperator;
 import org.rumbledb.items.structured.JSoundDataFrame;
 import org.rumbledb.items.xml.XMLDocumentPosition;
 import org.rumbledb.runtime.RuntimeIterator;
 import org.rumbledb.runtime.flwor.NativeClauseContext;
-import org.rumbledb.runtime.misc.ComparisonIterator;
 import org.rumbledb.runtime.update.primitives.Collection;
 import org.rumbledb.types.FunctionSignature;
 import org.rumbledb.types.ItemType;
@@ -59,15 +55,12 @@ public Item copy(boolean mutable) {
 
     @Override
     public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
         if (other instanceof Item otherItem) {
             if (otherItem.isAtomic()) {
-                long c = ComparisonIterator.compareItems(
-                    this,
-                    otherItem,
-                    ComparisonOperator.VC_EQ,
-                    ExceptionMetadata.EMPTY_METADATA
-                );
-                return c == 0;
+                return AtomicItemEquivalence.equivalent(this, otherItem);
             }
             return this.itemToAnnotate.equals(otherItem);
         }
@@ -76,7 +69,9 @@ public boolean equals(Object other) {
 
     @Override
     public int hashCode() {
-        return Objects.hash(this.itemToAnnotate, this.type);
+        return this.isAtomic()
+            ? AtomicItemEquivalence.hash(this)
+            : this.itemToAnnotate.hashCode();
     }
 
 

src/main/java/org/rumbledb/items/AnyURIItem.java

@@ -25,14 +25,11 @@
 import java.net.URISyntaxException;
 
 import org.rumbledb.api.Item;
-import org.rumbledb.exceptions.ExceptionMetadata;
-import org.rumbledb.expressions.comparison.ComparisonExpression.ComparisonOperator;
-import org.rumbledb.runtime.misc.ComparisonIterator;
 import org.rumbledb.types.BuiltinTypesCatalogue;
 import org.rumbledb.types.ItemType;
 
 
-public class AnyURIItem implements Item {
+public class AnyURIItem extends AbstractAtomicItem {
 
 
     @Serial
@@ -53,20 +50,6 @@ public Item copy(boolean mutable) {
         return new AnyURIItem(this.value.toString());
     }
 
-    @Override
-    public boolean equals(Object other) {
-        if (other instanceof Item otherItem) {
-            long c = ComparisonIterator.compareItems(
-                this,
-                otherItem,
-                ComparisonOperator.VC_EQ,
-                ExceptionMetadata.EMPTY_METADATA
-            );
-            return c == 0;
-        }
-        return false;
-    }
-
     static URI parseAnyURIString(String anyURIString) throws IllegalArgumentException {
         if (anyURIString == null)
             throw new IllegalArgumentException();
@@ -87,11 +70,6 @@ public boolean getEffectiveBooleanValue() {
         return !this.value.toString().isEmpty();
     }
 
-    @Override
-    public int hashCode() {
-        return this.value.hashCode();
-    }
-
     public URI getValue() {
         return this.value;
     }

src/main/java/org/rumbledb/items/ArrayItem.java

@@ -36,7 +36,7 @@
 import org.rumbledb.types.ItemTypeFactory;
 
 
-public class ArrayItem implements Item {
+public class ArrayItem extends AbstractArrayItem {
 
 
     @Serial
@@ -81,24 +81,6 @@ public Item copy(boolean mutable) {
         return copy;
     }
 
-    public boolean equals(Object other) {
-        if (!(other instanceof Item otherItem)) {
-            return false;
-        }
-        if (!otherItem.isArray()) {
-            return false;
-        }
-        if (getSize() != otherItem.getSize()) {
-            return false;
-        }
-        for (int i = 0; i < getSize(); ++i) {
-            if (!getItemAt(i).equals(otherItem.getItemAt(i))) {
-                return false;
-            }
-        }
-        return true;
-    }
-
     // region arrays
 
     @Override
@@ -209,14 +191,6 @@ public void removeSequenceAt(int index) {
 
 
 
-    public int hashCode() {
-        int result = 1;
-        for (int i = 0; i < getSize(); ++i) {
-            result = 31 * result + getItemAt(i).hashCode();
-        }
-        return result;
-    }
-
     @Override
     public ItemType getDynamicType() {
         if (this.arrayItems.isEmpty()) {