Scala example source code file (NameTransformer.scala)

This example Scala source code file (NameTransformer.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

array, char, local_suffix_string, module, name_join_string, opcodes, scala_name_join_string, setter_suffix_string, string, stringbuilder

The NameTransformer.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package reflect

/** Provides functions to encode and decode Scala symbolic names.
 *  Also provides some constants.
 */
object NameTransformer {
  // XXX Short term: providing a way to alter these without having to recompile
  // the compiler before recompiling the compiler.
  val MODULE_SUFFIX_STRING          = sys.props.getOrElse("SCALA_MODULE_SUFFIX_STRING", "$")
  val NAME_JOIN_STRING              = sys.props.getOrElse("SCALA_NAME_JOIN_STRING", "$")
  val MODULE_INSTANCE_NAME          = "MODULE$"
  val LOCAL_SUFFIX_STRING           = " "
  val SETTER_SUFFIX_STRING          = "_$eq"
  val TRAIT_SETTER_SEPARATOR_STRING = "$_setter_$"

  private val nops = 128
  private val ncodes = 26 * 26

  private class OpCodes(val op: Char, val code: String, val next: OpCodes)

  private val op2code = new Array[String](nops)
  private val code2op = new Array[OpCodes](ncodes)
  private def enterOp(op: Char, code: String) = {
    op2code(op.toInt) = code
    val c = (code.charAt(1) - 'a') * 26 + code.charAt(2) - 'a'
    code2op(c.toInt) = new OpCodes(op, code, code2op(c))
  }

  /* Note: decoding assumes opcodes are only ever lowercase. */
  enterOp('~', "$tilde")
  enterOp('=', "$eq")
  enterOp('<', "$less")
  enterOp('>', "$greater")
  enterOp('!', "$bang")
  enterOp('#', "$hash")
  enterOp('%', "$percent")
  enterOp('^', "$up")
  enterOp('&', "$amp")
  enterOp('|', "$bar")
  enterOp('*', "$times")
  enterOp('/', "$div")
  enterOp('+', "$plus")
  enterOp('-', "$minus")
  enterOp(':', "$colon")
  enterOp('\\', "$bslash")
  enterOp('?', "$qmark")
  enterOp('@', "$at")

  /** Replace operator symbols by corresponding `\$opname`.
   *
   *  @param name the string to encode
   *  @return     the string with all recognized opchars replaced with their encoding
   */
  def encode(name: String): String = {
    var buf: StringBuilder = null
    val len = name.length()
    var i = 0
    while (i < len) {
      val c = name charAt i
      if (c < nops && (op2code(c.toInt) ne null)) {
        if (buf eq null) {
          buf = new StringBuilder()
          buf.append(name.substring(0, i))
        }
        buf.append(op2code(c.toInt))
      /* Handle glyphs that are not valid Java/JVM identifiers */
      }
      else if (!Character.isJavaIdentifierPart(c)) {
        if (buf eq null) {
          buf = new StringBuilder()
          buf.append(name.substring(0, i))
        }
        buf.append("$u%04X".format(c.toInt))
      }
      else if (buf ne null) {
        buf.append(c)
      }
      i += 1
    }
    if (buf eq null) name else buf.toString()
  }

  /** Replace `\$opname` by corresponding operator symbol.
   *
   *  @param name0 the string to decode
   *  @return      the string with all recognized operator symbol encodings replaced with their name
   */
  def decode(name0: String): String = {
    //System.out.println("decode: " + name);//DEBUG
    val name = if (name0.endsWith("<init>")) name0.stripSuffix("<init>") + "this"
               else name0
    var buf: StringBuilder = null
    val len = name.length()
    var i = 0
    while (i < len) {
      var ops: OpCodes = null
      var unicode = false
      val c = name charAt i
      if (c == '$' && i + 2 < len) {
        val ch1 = name.charAt(i+1)
        if ('a' <= ch1 && ch1 <= 'z') {
          val ch2 = name.charAt(i+2)
          if ('a' <= ch2 && ch2 <= 'z') {
            ops = code2op((ch1 - 'a') * 26 + ch2 - 'a')
            while ((ops ne null) && !name.startsWith(ops.code, i)) ops = ops.next
            if (ops ne null) {
              if (buf eq null) {
                buf = new StringBuilder()
                buf.append(name.substring(0, i))
              }
              buf.append(ops.op)
              i += ops.code.length()
            }
            /* Handle the decoding of Unicode glyphs that are
             * not valid Java/JVM identifiers */
          } else if ((len - i) >= 6 && // Check that there are enough characters left
                     ch1 == 'u' &&
                     ((Character.isDigit(ch2)) ||
                     ('A' <= ch2 && ch2 <= 'F'))) {
            /* Skip past "$u", next four should be hexadecimal */
            val hex = name.substring(i+2, i+6)
            try {
              val str = Integer.parseInt(hex, 16).toChar
              if (buf eq null) {
                buf = new StringBuilder()
                buf.append(name.substring(0, i))
              }
              buf.append(str)
              /* 2 for "$u", 4 for hexadecimal number */
              i += 6
              unicode = true
            } catch {
              case _:NumberFormatException =>
                /* `hex` did not decode to a hexadecimal number, so
                 * do nothing. */
            }
          }
        }
      }
      /* If we didn't see an opcode or encoded Unicode glyph, and the
        buffer is non-empty, write the current character and advance
         one */
      if ((ops eq null) && !unicode) {
        if (buf ne null)
          buf.append(c)
        i += 1
      }
    }
    //System.out.println("= " + (if (buf == null) name else buf.toString()));//DEBUG
    if (buf eq null) name else buf.toString()
  }
}