fi.pelam.csv.cell.ColKey.scala Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of pelam-scala-csv_2.12 Show documentation

Scala library for reading and writing CSV data with an optional high level API. Supports structured access to tabular data and a form of CSV format detection.

The newest version!

/*
 * This file is part of pelam-scala-csv
 *
 * Copyright © Peter Lamberg 2015 ([email protected])
 *
 * 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 fi.pelam.csv.cell

/**
 * Type for columns numbers used in parsed CSV data.
 *
 * This corresponds to Nth position separated by separator characters on each line in CSV text file.
 *
 * Most interesting functionality is the conversion of integer indices into alphabetical numbering
 * used in spreadsheet programs.
 *
 * @constructor Construct a column key object for given zero based column index integer.
 *
 * @param index zero based column number (column index).
 */
final case class ColKey(index: Int) extends AxisKey[ColKey] {

  import ColKey._

  /**
   * Represents the column index as an one based integer as well as in alphabetical numbering used
   * in spreadsheet programs.
   */
  override def toString(): String = {
    s"Column ${toAlphabetical(index)} (${index})"
  }

  override def updated(newIndex: Int) = copy(index = newIndex)

  override def withOffset(offset: Int) = copy(index = index + offset)
}

object ColKey {
  val zero: ColKey = ColKey(0)
  val invalid: ColKey = ColKey(Int.MinValue / 2)

  /**
   * Converts integer into letters as is typically done for column numbers in spreadsheet programs.
   *
   * {{{ scala> ColKey.toAlphabetical(27)
   * res0: String = AB
   * }}}
   * @param index zero based column number
   */
  def toAlphabetical(index: Integer): String = {
    var i = index
    var result = ""

    val alphabetSize = 'Z' - 'A' + 1
    do {
      result = ('A' + i % alphabetSize).toChar + result
      // For most significant "digit" the radix is actually 27 because we can think empty string ""
      // as one of the digits.
      i = i / alphabetSize - 1
    } while (i >= 0)

    result
  }
}