heron/api/src/scala/org/apache/heron/streamlet/scala/Builder.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 limitations
 * under the License.
 */
package org.apache.heron.streamlet.scala

import org.apache.heron.streamlet.scala.impl.BuilderImpl

/**
  * Builder is used to register all sources. Builder thus keeps track
  * of all the starting points of the computation DAG and uses this
  * information to build the topology
  */
object Builder {
  def newBuilder(): Builder =
    new BuilderImpl(org.apache.heron.streamlet.Builder.newBuilder())
}

/**
  * Builder is used to register all sources. Builder thus keeps track
  * of all the starting points of the computation DAG and uses this
  * information to build the topology
  */
trait Builder {

  /**
    * All sources of the computation should register using addSource.
    *
    * @param supplier The supplier function that is used to create the streamlet
    * @return a Streamlet representation of the supplier object
    */
  def newSource[R](supplier: () => R): Streamlet[R]

  /**
    * Creates a new Streamlet using the underlying generator
    *
    * @param generator The generator that generates the tuples of the streamlet
    * @return  a Streamlet representation of the source object
    */
  def newSource[R](generator: Source[R]): Streamlet[R]
}