flink-libraries/flink-table/src/main/scala/org/apache/flink/table/expressions/windowProperties.scala

/*
 * 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
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package org.apache.flink.table.expressions

import org.apache.calcite.rex.RexNode
import org.apache.calcite.tools.RelBuilder
import org.apache.flink.table.api.types.{DataTypes, InternalType}
import org.apache.flink.table.calcite.FlinkRelBuilder
import FlinkRelBuilder.NamedWindowProperty
import org.apache.flink.table.plan.logical.LogicalExprVisitor
import org.apache.flink.table.validate.{ValidationFailure, ValidationSuccess}

trait WindowProperty {

  def toNamedWindowProperty(name: String): NamedWindowProperty

  def resultType: InternalType

}

abstract class AbstractWindowProperty(child: Expression)
  extends UnaryExpression
  with WindowProperty {

  override def toString = s"WindowProperty($child)"

  override private[flink] def toRexNode(implicit relBuilder: RelBuilder): RexNode =
    throw new UnsupportedOperationException("WindowProperty cannot be transformed to RexNode.")

  override private[flink] def validateInput() =
    if (child.isInstanceOf[WindowReference]) {
      ValidationSuccess
    } else {
      ValidationFailure("Child must be a window reference.")
    }

  def toNamedWindowProperty(name: String): NamedWindowProperty = NamedWindowProperty(name, this)
}

case class WindowStart(child: Expression) extends AbstractWindowProperty(child) {

  override def resultType = DataTypes.TIMESTAMP

  override def toString: String = s"start($child)"

  override def accept[T](logicalExprVisitor: LogicalExprVisitor[T]): T =
    logicalExprVisitor.visit(this)
}

case class WindowEnd(child: Expression) extends AbstractWindowProperty(child) {

  override def resultType = DataTypes.TIMESTAMP

  override def toString: String = s"end($child)"

  override def accept[T](logicalExprVisitor: LogicalExprVisitor[T]): T =
    logicalExprVisitor.visit(this)
}