Add YearMonthIntervalType

sql/catalyst/src/main/scala/org/apache/spark/sql/types/YearMonthIntervalType.scala

@@ -0,0 +1,68 @@
+/*
+ * 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.apache.spark.sql.types
+
+import scala.math.Ordering
+import scala.reflect.runtime.universe.typeTag
+
+import org.apache.spark.annotation.Unstable
+
+/**
+ * The type represents year-month intervals of the SQL standard. A year-month interval is made up
+ * of a contiguous subset of the following fields:
+ *   - MONTH, months within years [0..11],
+ *   - YEAR, years in the range [0..178956970].
+ *
+ * `YearMonthIntervalType` represents positive as well as negative year-month intervals.
+ *
+ * Please use the singleton `DataTypes.YearMonthIntervalType` to refer the type.
+ *
+ * @since 3.2.0
+ */
+@Unstable
+class YearMonthIntervalType private() extends AtomicType {
+  /**
+   * Internally, values of year-month intervals are stored in `Int` values as amount of months
+   * that are calculated by the formula:
+   *   -/+ (12 * YEAR + MONTH)
+   */
+  private[sql] type InternalType = Int
+
+  @transient private[sql] lazy val tag = typeTag[InternalType]
+
+  private[sql] val ordering = implicitly[Ordering[InternalType]]
+
+  /**
+   * Year-month interval values always occupy 4 bytes.
+   * The YEAR field is constrained by the upper bound 178956970 to fit to `Int`.
+   */
+  override def defaultSize: Int = 4
+
+  private[spark] override def asNullable: YearMonthIntervalType = this
+}
+
+/**
+ * The companion case object and its class is separated so the companion object also subclasses
+ * the YearMonthIntervalType class. Otherwise, the companion object would be of type
+ * "YearMonthIntervalType$" in byte code. Defined with a private constructor so the companion object
+ * is the only possible instantiation.
+ *
+ * @since 3.2.0
+ */
+@Unstable
+case object YearMonthIntervalType extends YearMonthIntervalType