CSV Driver

CSVRuleDriver

package demo

import java.sql.DriverManager
import java.util.Properties
import java.sql.ResultSet

object RuleQueryProcessor extends App {

  val nestedSelect = """select cpu from ruleData where cpu > (select cpu from ruleData limit 1) and mem < (select mem from ruleData limit 1)"""

  val nestedSelect_in = """select cpu from ruleData where cpu in (select cpu from ruleData)"""

  val nestedSelect_with_2_col = """select cpu from ruleData where cpu = mem"""

  val nestedSelect_with_sum = """select sum(cpu) from ruleData limit 1"""

  val nonNested = """select * from ruleData"""

  val csv = CSVDocConfig("cpu,mem,disk,io", "Int,Int,Int,Int")
  val driver = CSVQueryDriver(csv)

  println("--")
  println(driver.executeQuery(nestedSelect).foreach { x => println(x.getString(1)) })
  println("--")
  println(driver.executeQuery(nestedSelect_in).foreach { x => println(x.getString(1)) })
  println("--")
  println(driver.executeQuery(nestedSelect_with_2_col).foreach { x => println(x.getString(1)) })
  println("--")
  println(driver.executeQuery(nestedSelect_with_sum).foreach { x => println(x.getString(1)) })
}

class CSVQueryDriver(props: Properties) {

  private val c = DriverManager.getConnection("jdbc:relique:csv:/data", props)

  val nestedRegexLimit = """.*(\(select.*\slimit\s\d+\)).*""".r

  val nestedRegex = """.*(\(select.*\)).*""".r

  def executeQuery(select: String) = {
    doExecuteQuery(evalForNestedQuery(select))
  }

  def evalForNestedQuery(nestedSelect: String): String = {
    nestedSelect match {
      case nestedRegexLimit(nested) =>
        println("matched -> " + nested)
        val rs = doExecuteQuery(nested.tail.take(nested.length() - 2))
        val x = rs.head.getString(1)
        evalForNestedQuery(nestedSelect.replace(nested, x))
      case nestedRegex(nested) =>
        println("matched plain select")
        val rs = doExecuteQuery(nested.tail.take(nested.length() - 2))
        val x = rs.map { x => x.getString(1) }.mkString(",")
        evalForNestedQuery(nestedSelect.replace(nested, "(" + x + ")"))
      case _ =>
        nestedSelect
    }
  }

  private def doExecuteQuery[T](query: String) = {
    val s = c.createStatement()
    val rs = s.executeQuery(query)
    val iter = new Iterator[ResultSet] {
      def hasNext = rs.next()
      def next() = rs
    }
    val x = iter.toSeq
    x
  }

  def close = c.close()

}

case class CSVDocConfig(headers: String, headerTypes: String)

object CSVQueryDriver {

  Class.forName("org.relique.jdbc.csv.CsvDriver")

  def apply(csvConfig: CSVDocConfig) = {
    val props = new Properties()
    props.put("headerline", csvConfig.headers)
    props.put("columnTypes", csvConfig.headerTypes)
    new CSVQueryDriver(props)
  }

}