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/*
 * 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.expressions

import org.apache.spark.annotation.Experimental
import org.apache.spark.sql.Column
import org.apache.spark.sql.catalyst.expressions._

/**
 * :: Experimental ::
 * Utility functions for defining window in DataFrames.
 *
 * {{{
 *   // PARTITION BY country ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
 *   Window.partitionBy("country").orderBy("date").rowsBetween(Long.MinValue, 0)
 *
 *   // PARTITION BY country ORDER BY date ROWS BETWEEN 3 PRECEDING AND 3 FOLLOWING
 *   Window.partitionBy("country").orderBy("date").rowsBetween(-3, 3)
 * }}}
 *
 * @since 1.4.0
 */
@Experimental
object Window {

  /**
   * Creates a [[WindowSpec]] with the partitioning defined.
   * @since 1.4.0
   */
  @_root_.scala.annotation.varargs
  def partitionBy(colName: String, colNames: String*): WindowSpec = {
    spec.partitionBy(colName, colNames : _*)
  }

  /**
   * Creates a [[WindowSpec]] with the partitioning defined.
   * @since 1.4.0
   */
  @_root_.scala.annotation.varargs
  def partitionBy(cols: Column*): WindowSpec = {
    spec.partitionBy(cols : _*)
  }

  /**
   * Creates a [[WindowSpec]] with the ordering defined.
   * @since 1.4.0
   */
  @_root_.scala.annotation.varargs
  def orderBy(colName: String, colNames: String*): WindowSpec = {
    spec.orderBy(colName, colNames : _*)
  }

  /**
   * Creates a [[WindowSpec]] with the ordering defined.
   * @since 1.4.0
   */
  @_root_.scala.annotation.varargs
  def orderBy(cols: Column*): WindowSpec = {
    spec.orderBy(cols : _*)
  }

  private[sql] def spec: WindowSpec = {
    new WindowSpec(Seq.empty, Seq.empty, UnspecifiedFrame)
  }

}

/**
 * :: Experimental ::
 * Utility functions for defining window in DataFrames.
 *
 * {{{
 *   // PARTITION BY country ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
 *   Window.partitionBy("country").orderBy("date").rowsBetween(Long.MinValue, 0)
 *
 *   // PARTITION BY country ORDER BY date ROWS BETWEEN 3 PRECEDING AND 3 FOLLOWING
 *   Window.partitionBy("country").orderBy("date").rowsBetween(-3, 3)
 * }}}
 *
 * @since 1.4.0
 */
@Experimental
class Window private()  // So we can see Window in JavaDoc.