feat: Add hasLabels(LabelExpression labels) for nodes. (#1146)

Closes #1141.

README.adoc

@@ -6,7 +6,7 @@
 :artifactId: neo4j-cypher-dsl
 
 // This will be next version and also the one that will be put into the manual for the main branch
-:neo4j-cypher-dsl-version: 2024.2.1-SNAPSHOT
+:neo4j-cypher-dsl-version: 2024.3.0-SNAPSHOT
 // This is the latest released version, used only in the readme
 :neo4j-cypher-dsl-version-latest: 2024.2.0
 

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/AbstractNode.java

@@ -41,6 +41,14 @@ public final Condition hasLabels(String... labelsToQuery) {
 				labelsToQuery);
 	}
 
+	@NotNull
+	@Override
+	public final Condition hasLabels(LabelExpression labels) {
+		return new HasLabelExpressionCondition(this.getSymbolicName()
+			.orElseThrow(() -> new IllegalStateException("Cannot query a node without a symbolic name.")),
+			labels);
+	}
+
 	@NotNull
 	@Override
 	public final Condition isEqualTo(Node otherNode) {

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/HasLabelExpressionCondition.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2019-2024 "Neo4j,"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed 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
+ *
+ *     https://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.neo4j.cypherdsl.core;
+
+import static org.apiguardian.api.API.Status.INTERNAL;
+
+import org.apiguardian.api.API;
+import org.neo4j.cypherdsl.core.ast.Visitor;
+
+/**
+ * A condition checking for the presence of label expressions on nodes.
+ *
+ * @author Michael J. Simons
+ * @since 2024.3.0
+ */
+@API(status = INTERNAL, since = "2024.3.0")
+record HasLabelExpressionCondition(SymbolicName nodeName, LabelExpression labelExpression) implements Condition {
+
+	@Override
+	public void accept(Visitor visitor) {
+
+		visitor.enter(this);
+		this.nodeName.accept(visitor);
+		this.labelExpression.accept(visitor);
+		visitor.leave(this);
+	}
+}

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/Node.java

@@ -63,11 +63,18 @@ public interface Node extends PatternElement, PropertyContainer, ExposesProperti
 	 * A condition that checks for the presence of labels on a node.
 	 *
 	 * @param labelsToQuery A list of labels to query
-	 * @return A condition that checks whether this node has all of the labels to query
+	 * @return A condition that checks whether this node has all the labels to query
 	 */
 	@NotNull @Contract(pure = true)
 	Condition hasLabels(String... labelsToQuery);
 
+	/**
+	 * A condition that checks for the presence of a label expression on a node
+	 * @since 2024.3.0
+	 */
+	@NotNull @Contract(pure = true)
+	Condition hasLabels(LabelExpression labels);
+
 	/**
 	 * Creates a new condition whether this node is equal to {@literal otherNode}.
 	 *

neo4j-cypher-dsl/src/test/java/org/neo4j/cypherdsl/core/LabelExpressionTest.java

@@ -20,14 +20,18 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 class LabelExpressionTest {
 
+	static final LabelExpression SIMPLE_OR = new LabelExpression("Person").or(new LabelExpression("Organization"));
+	static final LabelExpression OR_AND_NOT = SIMPLE_OR.and(new LabelExpression("Sanctioned").negate());
+
 	@Test // GH-1077
 	void labelExpressionsShouldWork1() {
 
-		var node = Cypher.node(new LabelExpression("Person").or(new LabelExpression("Organization"))).named("n");
+		var node = Cypher.node(SIMPLE_OR).named("n");
 		var cypher = Cypher.match(node).returning(node).build().getCypher();
 
 		assertThat(cypher).isEqualTo("MATCH (n:`Person`|`Organization`) RETURN n");
@@ -36,10 +40,93 @@ void labelExpressionsShouldWork1() {
 	@Test // GH-1077
 	void labelExpressionsShouldWork2() {
 
-		var node = Cypher.node(new LabelExpression("Person").or(new LabelExpression("Organization"))
-			.and(new LabelExpression("Sanctioned").negate())).named("n");
+		var node = Cypher.node(OR_AND_NOT).named("n");
 		var cypher = Cypher.match(node).returning(node).build().getCypher();
 
 		assertThat(cypher).isEqualTo("MATCH (n:(`Person`|`Organization`)&!`Sanctioned`) RETURN n");
 	}
+
+	@Nested
+	class AsConditions {
+
+		@Test // GH-1077
+		void labelExpressionsShouldWork1() {
+
+			var node = Cypher.anyNode("n");
+			var cypher = Cypher.match(node).where(node.hasLabels(SIMPLE_OR)).returning(node).build().getCypher();
+
+			assertThat(cypher).isEqualTo("MATCH (n) WHERE n:`Person`|`Organization` RETURN n");
+		}
+
+		@Test // GH-1077
+		void labelExpressionsShouldWork2() {
+
+			var node = Cypher.anyNode("n");
+			var cypher = Cypher.match(node).where(node.hasLabels(OR_AND_NOT)).returning(node).build().getCypher();
+
+			assertThat(cypher).isEqualTo("MATCH (n) WHERE n:(`Person`|`Organization`)&!`Sanctioned` RETURN n");
+		}
+
+		@Test // GH-1141
+		void labelExpressionsInPredicates() {
+
+			var movieOrFilm = new LabelExpression("Movie").or(new LabelExpression("Film"));
+
+			String statement;
+			Node a = Cypher.node("Person").withProperties("name", Cypher.literalOf("Keanu Reeves")).named("a");
+			Node b = Cypher.anyNode("b");
+
+			statement = Cypher.match(a)
+				.returning(
+					Cypher.listBasedOn(a.relationshipBetween(b))
+						.where(b.hasLabels(movieOrFilm).and(b.property("released").isNotNull()))
+						.returning(b.property("released"))
+						.as("years"))
+				.build().getCypher();
+			assertThat(statement)
+				.isEqualTo(
+					"MATCH (a:`Person` {name: 'Keanu Reeves'}) RETURN [(a)--(b) WHERE (b:`Movie`|`Film` AND b.released IS NOT NULL) | b.released] AS years");
+
+			statement = Cypher.match(a)
+				.returning(
+					Cypher.listBasedOn(a.relationshipBetween(b))
+						.where(
+							b.hasLabels(movieOrFilm)
+								.and(b.property("released").isNotNull())
+								.or(b.property("title").isEqualTo(Cypher.literalOf("The Matrix")))
+								.or(b.property("title").isEqualTo(Cypher.literalOf("The Matrix 2"))))
+						.returning(b.property("released"))
+						.as("years"))
+				.build().getCypher();
+			assertThat(statement)
+				.isEqualTo(
+					"MATCH (a:`Person` {name: 'Keanu Reeves'}) RETURN [(a)--(b) WHERE ((b:`Movie`|`Film` AND b.released IS NOT NULL) OR b.title = 'The Matrix' OR b.title = 'The Matrix 2') | b.released] AS years");
+
+			statement = Cypher.match(a)
+				.returning(
+					Cypher.listBasedOn(a.relationshipBetween(b))
+						.where(b.hasLabels(movieOrFilm))
+						.and(b.property("released").isNotNull())
+						.or(b.property("title").isEqualTo(Cypher.literalOf("The Matrix")))
+						.or(b.property("title").isEqualTo(Cypher.literalOf("The Matrix 2")))
+						.returning(b.property("released"))
+						.as("years"))
+				.build().getCypher();
+
+			assertThat(statement)
+				.isEqualTo(
+					"MATCH (a:`Person` {name: 'Keanu Reeves'}) RETURN [(a)--(b) WHERE ((b:`Movie`|`Film` AND b.released IS NOT NULL) OR b.title = 'The Matrix' OR b.title = 'The Matrix 2') | b.released] AS years");
+
+			statement = Cypher.match(a)
+				.returning(
+					Cypher.listBasedOn(a.relationshipBetween(b))
+						.where(b.hasLabels(movieOrFilm))
+						.returning(b.property("released"))
+						.as("years"))
+				.build().getCypher();
+			assertThat(statement)
+				.isEqualTo(
+					"MATCH (a:`Person` {name: 'Keanu Reeves'}) RETURN [(a)--(b) WHERE b:`Movie`|`Film` | b.released] AS years");
+		}
+	}
 }