| /* |
| * 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.wayang.api.util |
| |
| import org.apache.wayang.api.dataquanta.{DataQuanta, DataQuantaBuilder} |
| |
| /** |
| * Caches products of [[DataQuantaBuilder]]s that need to be executed at once, e.g., because they |
| * belong to different [[org.apache.wayang.core.plan.wayangplan.OutputSlot]]s of the same custom [[org.apache.wayang.core.plan.wayangplan.Operator]]. |
| */ |
| class DataQuantaBuilderCache { |
| |
| private var _cache: IndexedSeq[DataQuanta[_]] = _ |
| |
| /** |
| * Tell whether there is something in this cache. |
| * |
| * @return whether the cache has been filled |
| */ |
| def hasCached = _cache != null |
| |
| /** |
| * Get previously cached [[DataQuanta]]. |
| * |
| * @param index index of the [[DataQuanta]] as they were passed in [[cache()]] |
| * @tparam T the requested type of [[DataQuanta]] |
| * @return the cached [[DataQuanta]] |
| */ |
| def apply[T](index: Int) = { |
| assert(hasCached) |
| _cache(index).asInstanceOf[DataQuanta[T]] |
| } |
| |
| /** |
| * Cache [[DataQuanta]]. Should only be called once. |
| * |
| * @param dataQuanta the [[DataQuanta]] that should be cached |
| */ |
| def cache(dataQuanta: Iterable[DataQuanta[_]]) = { |
| assert(!hasCached) |
| _cache = dataQuanta.toIndexedSeq |
| } |
| |
| } |