scala.annotation.switch.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala.annotation
/** An annotation to be applied to a match expression. If present,
* the compiler will verify that the match has been compiled to a
* [[http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-3.html#jvms-3.10 tableswitch or lookupswitch]]
* and issue an error if it instead compiles into a series of conditional expressions.
* Example usage:
{{{
val Constant = 'Q'
def tokenMe(ch: Char) = (ch: @switch) match {
case ' ' | '\t' | '\n' => 1
case 'A' | 'Z' | '$' => 2
case '5' | Constant => 3 // a non-literal may prevent switch generation: this would not compile
case _ => 4
}
}}}
*
* Note: for pattern matches with one or two cases, the compiler generates jump instructions.
* Annotating such a match with `@switch` does not issue any warning.
*
* @author Paul Phillips
* @since 2.8
*/
final class switch extends scala.annotation.StaticAnnotation