Scala example source code file (Naming.scala)

This example Scala source code file (Naming.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

esc, interpreter_var_prefix, namecreator, naming, sessionnames, string, unit, utilities

The Naming.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala
package tools.nsc
package interpreter

import scala.util.Properties.lineSeparator
import scala.util.matching.Regex

/** This is for name logic which is independent of the compiler (notice there's no Global.)
 *  That includes at least generating, metaquoting, mangling, and unmangling.
 */
trait Naming {
  def unmangle(str: String): String = {
    val ESC = '\u001b'
    val cleaned = removeIWPackages(removeLineWrapper(str))
    // Looking to exclude binary data which hoses the terminal, but
    // let through the subset of it we need, like whitespace and also
    // <ESC> for ansi codes.
    val binaryChars = cleaned count (ch => ch < 32 && !ch.isWhitespace && ch != ESC)
    // Lots of binary chars - translate all supposed whitespace into spaces
    // except supposed line endings, otherwise scrubbed lines run together
    if (binaryChars > 5)  // more than one can count while holding a hamburger
      cleaned map {
        case c if lineSeparator contains c  => c
        case c if c.isWhitespace            => ' '
        case c if c < 32                    => '?'
        case c                              => c
      }
    // Not lots - preserve whitespace and ESC
    else
      cleaned map (ch => if (ch.isWhitespace || ch == ESC) ch else if (ch < 32) '?' else ch)
  }

  // The two name forms this is catching are the two sides of this assignment:
  //
  // $line3.$read.$iw.$iw.Bippy =
  //   $line3.$read$$iw$$iw$Bippy@4a6a00ca
  lazy val lineRegex = {
    val sn = sessionNames
    val members = List(sn.read, sn.eval, sn.print) map Regex.quote mkString ("(?:", "|", ")")
    debugging("lineRegex")(Regex.quote(sn.line) + """\d+[./]""" + members + """[$.]""")
  }

  private def removeLineWrapper(s: String) = s.replaceAll(lineRegex, "")
  private def removeIWPackages(s: String)  = s.replaceAll("""\$iw[$.]""", "")

  trait SessionNames {
    // All values are configurable by passing e.g. -Dscala.repl.name.read=XXX
    final def propOr(name: String): String = propOr(name, "$" + name)
    final def propOr(name: String, default: String): String =
      sys.props.getOrElse("scala.repl.name." + name, default)

    // Prefixes used in repl machinery.  Default to $line, $read, etc.
    def line   = propOr("line")
    def read   = propOr("read")
    def eval   = propOr("eval")
    def print  = propOr("print")
    def result = propOr("result")

    // The prefix for unnamed results: by default res0, res1, etc.
    def res   = propOr("res", "res")  // INTERPRETER_VAR_PREFIX
    // Internal ones
    def ires  = propOr("ires")
  }
  lazy val sessionNames: SessionNames = new SessionNames { }

  /** Generates names pre0, pre1, etc. via calls to apply method */
  class NameCreator(pre: String) {
    private var x = -1
    var mostRecent: String = ""

    def apply(): String = {
      x += 1
      mostRecent = pre + x
      mostRecent
    }
    def reset(): Unit = x = -1
    def didGenerate(name: String) =
      (name startsWith pre) && ((name drop pre.length) forall (_.isDigit))
  }

  private lazy val userVar     = new NameCreator(sessionNames.res)  // var name, like res0
  private lazy val internalVar = new NameCreator(sessionNames.ires) // internal var name, like $ires0

  def isUserVarName(name: String)     = userVar didGenerate name
  def isInternalVarName(name: String) = internalVar didGenerate name

  val freshLineId            = {
    var x = 0
    () => { x += 1 ; x }
  }
  def freshUserVarName() = userVar()
  def freshInternalVarName() = internalVar()

  def resetAllCreators() {
    userVar.reset()
    internalVar.reset()
  }

  def mostRecentVar = userVar.mostRecent
}