wayang-api/wayang-api-scala-java/code/main/scala/org/apache/wayang/api/dataquanta/builder/RepeatDataQuantaBuilder.scala

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 *   Licensed to the Apache Software Foundation (ASF) under one
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 *   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
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 *   Unless required by applicable law or agreed to in writing,
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 *   KIND, either express or implied.  See the License for the
 *   specific language governing permissions and limitations
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package org.apache.wayang.api.dataquanta.builder

import org.apache.wayang.api.JavaPlanBuilder
import org.apache.wayang.api.dataquanta.{DataQuanta, DataQuantaBuilder}
import org.apache.wayang.api.util.TypeTrap

import java.util.function.{Function => JavaFunction}

/**
 * [[DataQuantaBuilder]] implementation for [[org.apache.wayang.basic.operators.DoWhileOperator]]s.
 *
 * @param inputDataQuanta [[DataQuantaBuilder]] for the input [[DataQuanta]]
 * @param numRepetitions  number of repetitions of the loop
 * @param bodyBuilder     builds the loop body
 */
class RepeatDataQuantaBuilder[T](inputDataQuanta: DataQuantaBuilder[_, T],
                                 numRepetitions: Int,
                                 bodyBuilder: JavaFunction[DataQuantaBuilder[_, T], DataQuantaBuilder[_, T]])
                                (implicit javaPlanBuilder: JavaPlanBuilder)
  extends BasicDataQuantaBuilder[RepeatDataQuantaBuilder[T], T] {

  // Reuse the input TypeTrap to enforce type equality between input and output.
  override def getOutputTypeTrap: TypeTrap = inputDataQuanta.outputTypeTrap

  // TODO: We could improve by combining the TypeTraps in the body loop.

  override protected def build =
    inputDataQuanta.dataQuanta().repeat(numRepetitions, startDataQuanta => {
      val loopStartbuilder = new FakeDataQuantaBuilder(startDataQuanta)
      bodyBuilder(loopStartbuilder).dataQuanta()
    })

}