scala.annotation.switch
final class switch extends Annotation with StaticAnnotation
An annotation to be applied to a match expression. If present, the compiler will
verify that the match has been compiled to a
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' | '$' => 2
case '5' | Constant => 3 // a non-literal may prevent switch generation: this would not compile
case _ => 4
}
Note: for pattern matches with one or two cases, the compiler generates jump
instructions. Annotating such a match with @switch
does not issue any warning.
Instance Constructors From scala.annotation.switch
new switch()
(defined at scala.annotation.switch)
Full Source:
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.annotation
/** An annotation to be applied to a match expression. If present,
* the compiler will verify that the match has been compiled to a
* [[http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-3.html#jvms-3.10 tableswitch or lookupswitch]]
* and issue an error if it instead compiles into a series of conditional expressions.
* Example usage:
{{{
val Constant = 'Q'
def tokenMe(ch: Char) = (ch: @switch) match {
case ' ' | '\t' | '\n' => 1
case 'A' | 'Z' | '$' => 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