org.apache.flink.table.plan.trait.TraitSetHelper.scala Maven / Gradle / Ivy

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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.flink.table.plan.`trait`

import org.apache.calcite.rel.{RelCollation, RelCollations, RelFieldCollation}
import org.apache.calcite.util.mapping.Mappings

import scala.collection.JavaConversions._
import scala.collection.mutable

/**
  * Utility for TraitSet
  */
object TraitSetHelper {

  /**
    * Apply collation based on the given mapping restrict. Returns RelCollations.EMPTY if there
    * exists collation fields which has no target values in the given mapping.
    *
    * @param collation collation which to apply mapping
    * @param mapping
    * @return A new collation after apply collation based on the given mapping restrict.
    *         Returns RelCollations.EMPTY if there exists collation fields which has no target
    *         values in the given mapping.
    */
  def apply(collation: RelCollation, mapping: Mappings.TargetMapping): RelCollation = {
    val fieldCollations = collation.getFieldCollations
    if (fieldCollations.isEmpty) collation
    else {
      val newFieldCollations = mutable.ArrayBuffer[RelFieldCollation]()
      fieldCollations.foreach { fieldCollation =>
        try {
          val i = mapping.getTargetOpt(fieldCollation.getFieldIndex)
          if (i >= 0) newFieldCollations.add(fieldCollation.copy(i)) else return RelCollations.EMPTY
        } catch {
          case _: IndexOutOfBoundsException => return RelCollations.EMPTY
        }
      }
      RelCollations.of(newFieldCollations: _*)
    }
  }

}