Scala example source code file (Tracer.scala)

This example Scala source code file (Tracer.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

any, any, anyref, boolean, io, lbrace, printstream, product, some, string, string, t, t, tracer, tracer

The Scala Tracer.scala source code

/* NSC -- new Scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala.tools.nsc
package util

import java.io.PrintStream

class Tracer(enabled: () => Boolean) {
  def out: PrintStream = System.out
  def intoString(x: Any): String = "" + x
  def stringify(x: Any): String = x match {
    case null                   => "null"
    case x: TraversableOnce[_]  => x map stringify mkString ", "
    case x: Product             => stringify(x.productIterator)
    case x: AnyRef              => intoString(x)
  }

  private val LBRACE = "{"
  private val RBRACE = "}"
  private var indentLevel = 0
  private def ind(s: String) = (" " * (indentLevel * 2)) + s
  private def indented[T](body: => T): T = {
    indentLevel += 1
    try body
    finally indentLevel -= 1
  }
  private def p(s: String) = {
    out.print(s)
    out.flush()
  }
  private def pin[T](x: T): T = {
    p(ind("" + x))
    x
  }
  def apply[T](name: String, args: => Any)(body: => T): T = {
    val result = body
    if (enabled()) {
      // concise output optimization
      val boolResult = result match {
        case x: Boolean => Some(x)
        case _          => None
      }
      p(ind("%s(%s) = %s\n".format(
        name,
        stringify(args),
        boolResult getOrElse LBRACE))
      )
      if (boolResult.isEmpty) {
        indented(pin(result))
        p("\n" + ind(RBRACE))
      }
      result
    }
    else result
  }
}

object Tracer {
  def apply(enabled: => Boolean): Tracer = new Tracer(() => enabled)
}