Scala example source code file (Precedence.scala)

This example Scala source code file (Precedence.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

annotation, anyval, char, errorname, int, ordered, precedence, string

The Precedence.scala Scala example source code

package scala
package reflect
package internal

import scala.annotation.switch
import Chars._

final class Precedence private (val level: Int) extends AnyVal with Ordered[Precedence] {
  def compare(that: Precedence): Int = level compare that.level
  override def toString = s"Precedence($level)"
}


object Precedence extends (Int => Precedence) {
  private val ErrorName = "<error>"
  private def isAssignmentOp(name: String) = name match {
    case "!=" | "<=" | ">=" | "" => false
    case _                       => name.last == '=' && name.head != '=' && isOperatorPart(name.head)
  }
  private def firstChar(ch: Char): Precedence = apply((ch: @switch) match {
    case '|'             => 2
    case '^'             => 3
    case '&'             => 4
    case '=' | '!'       => 5
    case '<' | '>'       => 6
    case ':'             => 7
    case '+' | '-'       => 8
    case '*' | '/' | '%' => 9
    case _               => if (isScalaLetter(ch)) 1 else 10
  })

  def apply(level: Int): Precedence = new Precedence(level)
  def apply(name: String): Precedence = name match {
    case "" | ErrorName            => this(-1)
    case _ if isAssignmentOp(name) => this(0)
    case _                         => firstChar(name charAt 0)
  }
}