Polishing.

Reuse H2 dialect settings in R2DBC-specific H2 dialect.
Refactor ArrayColumns support classes, into toplevel-types. Let R2DBC H2 sublass the relational H2Dialect to decouple from Postgres.

See #1287
Original pull request #1297

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/JdbcArrayColumns.java

@@ -23,19 +23,14 @@ import org.springframework.data.relational.core.dialect.ArrayColumns;
  * {@link org.springframework.data.relational.core.dialect.ArrayColumns} that offer JDBC-specific functionality.
  *
  * @author Jens Schauder
+ * @author Mark Paluch
  * @since 2.3
  */
 public interface JdbcArrayColumns extends ArrayColumns {
 
 	@Override
 	default Class<?> getArrayType(Class<?> userType) {
-
-		Class<?> componentType = userType;
-		while (componentType.isArray()) {
-			componentType = componentType.getComponentType();
-		}
-
-		return componentType;
+		return ArrayColumns.unwrapComponentType(userType);
 	}
 
 	/**

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/dialect/JdbcPostgresDialect.java

@@ -38,11 +38,11 @@ public class JdbcPostgresDialect extends PostgresDialect implements JdbcDialect
 		return ARRAY_COLUMNS;
 	}
 
-	static class JdbcPostgresArrayColumns extends PostgresArrayColumns implements JdbcArrayColumns {
+	static class JdbcPostgresArrayColumns implements JdbcArrayColumns {
 
 		@Override
-		public Class<?> getArrayType(Class<?> userType) {
-			return JdbcArrayColumns.super.getArrayType(userType);
+		public boolean isSupported() {
+			return true;
 		}
 
 		@Override

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/dialect/H2Dialect.java

@@ -1,34 +1,57 @@
+/*
+ * Copyright 2019-2022 the original author or authors.
+ *
+ * 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.springframework.data.r2dbc.dialect;
 
-import org.springframework.data.relational.core.dialect.AnsiDialect;
-import org.springframework.data.relational.core.dialect.LockClause;
+import org.springframework.data.relational.core.dialect.ArrayColumns;
+import org.springframework.data.relational.core.dialect.ObjectArrayColumns;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
+import org.springframework.data.util.Lazy;
+import org.springframework.r2dbc.core.binding.BindMarkersFactory;
 
 /**
- * An SQL dialect for H2 in Postgres Compatibility mode.
+ * R2DBC dialect for H2.
  *
  * @author Mark Paluch
  * @author Jens Schauder
  * @author Diego Krupitza
  */
-public class H2Dialect extends PostgresDialect {
+public class H2Dialect extends org.springframework.data.relational.core.dialect.H2Dialect implements R2dbcDialect {
 
 	/**
 	 * Singleton instance.
 	 */
 	public static final H2Dialect INSTANCE = new H2Dialect();
 
+	private static final BindMarkersFactory INDEXED = BindMarkersFactory.indexed("$", 1);
+
+	private final Lazy<ArrayColumns> arrayColumns = Lazy
+			.of(() -> new SimpleTypeArrayColumns(ObjectArrayColumns.INSTANCE, getSimpleTypeHolder()));
+
+	@Override
+	public BindMarkersFactory getBindMarkersFactory() {
+		return INDEXED;
+	}
+
 	@Override
 	public String renderForGeneratedValues(SqlIdentifier identifier) {
 		return identifier.getReference(getIdentifierProcessing());
 	}
 
 	@Override
-	public LockClause lock() {
-		// H2 Dialect does not support the same lock keywords as PostgreSQL, but it supports the ANSI SQL standard.
-		// see https://www.h2database.com/html/commands.html
-		// and https://www.h2database.com/html/features.html#compatibility
-		return AnsiDialect.INSTANCE.lock();
+	public ArrayColumns getArraySupport() {
+		return this.arrayColumns.get();
 	}
-
 }

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/dialect/PostgresDialect.java

@@ -24,8 +24,8 @@ import org.springframework.data.geo.Box;
 import org.springframework.data.geo.Circle;
 import org.springframework.data.geo.Point;
 import org.springframework.data.geo.Polygon;
-import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.relational.core.dialect.ArrayColumns;
+import org.springframework.data.relational.core.dialect.ObjectArrayColumns;
 import org.springframework.data.util.Lazy;
 import org.springframework.lang.NonNull;
 import org.springframework.r2dbc.core.binding.BindMarkersFactory;
@@ -79,9 +79,8 @@ public class PostgresDialect extends org.springframework.data.relational.core.di
 
 	private static final BindMarkersFactory INDEXED = BindMarkersFactory.indexed("$", 1);
 
-	private final Lazy<ArrayColumns> arrayColumns = Lazy.of(() -> new R2dbcArrayColumns(
-			org.springframework.data.relational.core.dialect.PostgresDialect.INSTANCE.getArraySupport(),
-			getSimpleTypeHolder()));
+	private final Lazy<ArrayColumns> arrayColumns = Lazy
+			.of(() -> new SimpleTypeArrayColumns(ObjectArrayColumns.INSTANCE, getSimpleTypeHolder()));
 
 	/*
 	 * (non-Javadoc)
@@ -137,37 +136,6 @@ public class PostgresDialect extends org.springframework.data.relational.core.di
 		return converters;
 	}
 
-	private static class R2dbcArrayColumns implements ArrayColumns {
-
-		private final ArrayColumns delegate;
-		private final SimpleTypeHolder simpleTypeHolder;
-
-		R2dbcArrayColumns(ArrayColumns delegate, SimpleTypeHolder simpleTypeHolder) {
-			this.delegate = delegate;
-			this.simpleTypeHolder = simpleTypeHolder;
-		}
-
-		@Override
-		public boolean isSupported() {
-			return this.delegate.isSupported();
-		}
-
-		@Override
-		public Class<?> getArrayType(Class<?> userType) {
-
-			Class<?> typeToUse = userType;
-			while (typeToUse.getComponentType() != null) {
-				typeToUse = typeToUse.getComponentType();
-			}
-
-			if (!this.simpleTypeHolder.isSimpleType(typeToUse)) {
-				throw new IllegalArgumentException("Unsupported array type: " + ClassUtils.getQualifiedName(typeToUse));
-			}
-
-			return this.delegate.getArrayType(typeToUse);
-		}
-	}
-
 	/**
 	 * If the class is present on the class path, invoke the specified consumer {@code action} with the class object,
 	 * otherwise do nothing.

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/dialect/SimpleTypeArrayColumns.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.springframework.data.r2dbc.dialect;
+
+import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.relational.core.dialect.ArrayColumns;
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link ArrayColumns} support based on {@link SimpleTypeHolder store-native simple types}.
+ *
+ * @author Mark Paluch
+ * @since 3.0
+ */
+record SimpleTypeArrayColumns(ArrayColumns delegate, SimpleTypeHolder simpleTypeHolder) implements ArrayColumns {
+
+	@Override
+	public boolean isSupported() {
+		return this.delegate.isSupported();
+	}
+
+	@Override
+	public Class<?> getArrayType(Class<?> userType) {
+
+		Class<?> typeToUse = ArrayColumns.unwrapComponentType(userType);
+
+		if (!this.simpleTypeHolder.isSimpleType(typeToUse)) {
+			throw new IllegalArgumentException(
+					"Unsupported array type: %s".formatted(ClassUtils.getQualifiedName(typeToUse)));
+		}
+
+		return this.delegate.getArrayType(typeToUse);
+	}
+}

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/AnsiDialect.java

@@ -17,8 +17,6 @@ package org.springframework.data.relational.core.dialect;
 
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
 import org.springframework.data.relational.core.sql.LockOptions;
-import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
 
 /**
  * An SQL dialect for the ANSI SQL standard.
@@ -72,7 +70,7 @@ public class AnsiDialect extends AbstractDialect {
 		}
 	};
 
-	private final AnsiArrayColumns ARRAY_COLUMNS = new AnsiArrayColumns();
+	private final ArrayColumns ARRAY_COLUMNS = ObjectArrayColumns.INSTANCE;
 
 	@Override
 	public LimitClause limit() {
@@ -89,22 +87,6 @@ public class AnsiDialect extends AbstractDialect {
 		return ARRAY_COLUMNS;
 	}
 
-	static class AnsiArrayColumns implements ArrayColumns {
-
-		@Override
-		public boolean isSupported() {
-			return true;
-		}
-
-		@Override
-		public Class<?> getArrayType(Class<?> userType) {
-
-			Assert.notNull(userType, "Array component type must not be null");
-
-			return ClassUtils.resolvePrimitiveIfNecessary(userType);
-		}
-	}
-
 	@Override
 	public IdentifierProcessing getIdentifierProcessing() {
 		return IdentifierProcessing.ANSI;

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/ArrayColumns.java

@@ -58,4 +58,21 @@ public interface ArrayColumns {
 			throw new UnsupportedOperationException("Array types not supported");
 		}
 	}
+
+	/**
+	 * Unwrap the nested {@link Class#getComponentType()} from a given {@link Class}.
+	 *
+	 * @param clazz the type to inspect.
+	 * @return the unwrapped component type.
+	 * @since 3.0
+	 */
+	static Class<?> unwrapComponentType(Class<?> clazz) {
+
+		Class<?> componentType = clazz;
+		while (componentType.isArray()) {
+			componentType = componentType.getComponentType();
+		}
+
+		return componentType;
+	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/ObjectArrayColumns.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.springframework.data.relational.core.dialect;
+
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link ArrayColumns} support using the actual object type or {@link Class#isPrimitive() boxed primitives} Java types.
+ *
+ * @author Mark Paluch
+ * @since 3.0
+ * @see ClassUtils#resolvePrimitiveIfNecessary
+ */
+public class ObjectArrayColumns implements ArrayColumns {
+
+	public static final ObjectArrayColumns INSTANCE = new ObjectArrayColumns();
+
+	@Override
+	public boolean isSupported() {
+		return true;
+	}
+
+	@Override
+	public Class<?> getArrayType(Class<?> userType) {
+
+		Assert.notNull(userType, "Array component type must not be null");
+
+		return ClassUtils.resolvePrimitiveIfNecessary(ArrayColumns.unwrapComponentType(userType));
+	}
+}

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/PostgresDialect.java

@@ -32,7 +32,6 @@ import org.springframework.data.relational.core.sql.SQL;
 import org.springframework.data.relational.core.sql.SimpleFunction;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
 import org.springframework.data.relational.core.sql.TableLike;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -76,7 +75,7 @@ public class PostgresDialect extends AbstractDialect {
 		}
 	};
 
-	private final PostgresArrayColumns ARRAY_COLUMNS = new PostgresArrayColumns();
+	private static final ObjectArrayColumns ARRAY_COLUMNS = ObjectArrayColumns.INSTANCE;
 
 	@Override
 	public LimitClause limit() {
@@ -146,22 +145,6 @@ public class PostgresDialect extends AbstractDialect {
 		}
 	}
 
-	protected static class PostgresArrayColumns implements ArrayColumns {
-
-		@Override
-		public boolean isSupported() {
-			return true;
-		}
-
-		@Override
-		public Class<?> getArrayType(Class<?> userType) {
-
-			Assert.notNull(userType, "Array component type must not be null");
-
-			return ClassUtils.resolvePrimitiveIfNecessary(userType);
-		}
-	}
-
 	@Override
 	public IdentifierProcessing getIdentifierProcessing() {
 		return IdentifierProcessing.create(Quoting.ANSI, LetterCasing.LOWER_CASE);
@@ -179,7 +162,7 @@ public class PostgresDialect extends AbstractDialect {
 				"org.postgresql.geometric.PGline", //
 				"org.postgresql.geometric.PGpath", //
 				"org.postgresql.geometric.PGpolygon", //
-				"org.postgresql.geometric.PGlseg"  //
+				"org.postgresql.geometric.PGlseg" //
 		);
 		simpleTypeNames.forEach(name -> ifClassPresent(name, simpleTypes::add));
 		return Collections.unmodifiableSet(simpleTypes);