com.landoop.connect.sql.SqlContext.scala Maven / Gradle / Ivy

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/*
/*
 * Copyright 2017 Landoop.
 *
 * Licensed 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 com.landoop.connect.sql

import com.landoop.json.sql.Field
import org.apache.calcite.sql.SqlSelect

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

class SqlContext(val fields: Iterable[Field]) {

  private val cache = FieldsMapBuilder(fields)

  def getFieldsForPath(parents: Seq[String]): Seq[Either[Field, String]] = {
    val key = parents.mkString(".")
    cache.getOrElse(key, Seq.empty)
  }

  private object FieldsMapBuilder {
    private def insertKey(key: String,
                          item: Either[Field, String],
                          map: Map[String, ArrayBuffer[Either[Field, String]]]): Map[String, ArrayBuffer[Either[Field, String]]] = {

      map.get(key) match {
        case None =>
          val buffer = ArrayBuffer.empty[Either[Field, String]]
          buffer += item
          map + (key -> buffer)

        case Some(buffer) =>
          if (!buffer.contains(item)) {
            buffer += item
          }
          map
      }
    }

    def apply(fields: Iterable[Field]): Map[String, Seq[Either[Field, String]]] = {
      fields.foldLeft(Map.empty[String, ArrayBuffer[Either[Field, String]]]) { case (map, field) =>
        if (field.hasParents) {
          val (_, m) = field.parents
            .foldLeft((new StringBuilder(), map)) { case ((builder, accMap), p) =>
              val localMap = insertKey(builder.toString(), Right(p), accMap)
              //if (builder.isEmpty) builder.append(p)
              builder.append(p) -> localMap
            }
          insertKey(field.parents.mkString("."), Left(field), m)
        } else {
          insertKey("", Left(field), map)
        }
      }
    }

    def apply(sql: SqlSelect): Map[String, Seq[Either[Field, String]]] = {
      apply(Field.from(sql))
    }
  }

}
*/