Scala example source code file (TableDef.scala)

This example Scala source code file (TableDef.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

any, boolean, column, int, list, seq, string, t, table, tabledef

The TableDef.scala Scala example source code

package scala
package reflect.internal.util

import TableDef._
import scala.language.postfixOps

/** A class for representing tabular data in a way that preserves
 *  its inner beauty.
 *  One creates an instance of TableDef by defining the columns of
 *  the table, then uses that to create an instance of Table by
 *  passing in a sequence of rows.
 */
class TableDef[T](_cols: Column[T]*) {
  // These operators are about all there is to it.
  /** Appends a column to the table. */
  def ~(next: Column[T])            = retThis(cols :+= next)

  // Below this point should all be considered private/internal.
  private var cols: List[Column[T]] = _cols.toList

  def defaultSep(index: Int)   = if (index > (cols.size - 2)) "" else " "
  def sepAfter(i: Int): String = defaultSep(i)
  def sepWidths                = cols.indices map (i => sepAfter(i).length)

  def colNames = cols map (_.name)
  def colFunctions = cols map (_.f)
  def colApply(el: T) = colFunctions map (f => f(el))
  def retThis(body: => Unit): this.type = { body ; this }

  class Table(val rows: Seq[T]) extends Seq[T] {
    def iterator          = rows.iterator
    def apply(index: Int) = rows(index)
    def length            = rows.length

    def maxColWidth(col: Column[T]) = col.name +: (rows map col.f) map (_.toString.length) max
    def specs = cols map (_ formatSpec rows)

    val colWidths   = cols map maxColWidth
    val rowFormat   = mkFormatString(sepAfter)
    val headFormat  = mkFormatString(i => " " * sepWidths(i))
    val argLists    = rows map colApply

    val headers = List(
      headFormat.format(colNames: _*),
      (colWidths, sepWidths).zipped map ((w1, w2) => "-" * w1 + " " * w2) mkString
    )

    def mkFormatString(sepf: Int => String): String =
      specs.zipWithIndex map { case (c, i) => c + sepf(i) } mkString

    def toFormattedSeq = argLists map (xs => rowFormat.format(xs: _*))
    def allToSeq = headers ++ toFormattedSeq

    override def toString = allToSeq mkString "\n"
  }

  def table(rows: Seq[T]) = new Table(rows)

  override def toString = cols.mkString("TableDef(", ", ", ")")
}

object TableDef {
  case class Column[-T](name: String, f: T => Any, left: Boolean) {
    def maxWidth(elems: Seq[T]): Int = name +: (elems map f) map (_.toString.length) max
    def formatSpec(elems: Seq[T]): String = {
      val justify = if (left) "-" else ""
      "%" + justify + maxWidth(elems) + "s"
    }
    override def toString = {
      val justify = if (left) "<<" else ">>"
      justify + "(" + name + ")"
    }
  }

  def apply[T](cols: Column[T]*) = new TableDef[T](cols: _*)
}