What is the use case for this weird switch mecanism

[deadalnix]

Le 31/10/2012 21:33, Chris Nicholson-Sauls a écrit :
> Some related actual code from a while back:
>
> ##################################################
> ParseTree prune ( ParseTree p ) {
> p.children = p.children.dup;
> foreach ( ref child ; p.children ) {
> child = prune( child );
> }
>
> switch ( p.ruleName ) {
> // strip prefix/suffix terminals, then if left with only one child, skip
> over it
> case "Args" :
> case "List" :
> case "Params" :
> case "Table" : p.children = p.children[ 1 .. $ - 1 ];
> if ( p.children.length == 1 ) {
>
> // skip over immediate child (always a "Series")
> case "QualIdent" :
> case "Type" : p.children = p.children[ 0 ].children;
> }
> break;
>
> // skip self if it has exactly one child
> case "Addition" :
> case "BoolAnd" :
> case "BoolOr" :
> case "Comparison" :
> case "Conditional" :
> case "MaybeParens" :
> case "Multiplication" :
> case "Postfix" :
> case "Primary" :
> case "Unary" : if ( p.children.length == 1 ) {
>
> // skip self
> case "Expression" :
> case "Field" :
> case "Ident" :
> case "Literal" :
> case "PathElem" :
> case "Statement" : p = p.children[ 0 ];
> }
> break;
>
> default:
> }
>
> return p;
> }
> ##################################################
>
> Without the loosely defined switch() statement syntax, this would have
> been a royal pain to piece together. Especially when each block of cases
> was evolving over time.
>
> There is also the trick of doing 'switch(val) with(EnumType) {...}' to
> bring an enum's members into scope so that cases can be written as 'case
> Foo:' rather than 'case EnumType.Foo:'.
>
> -- Chris Nicholson-Sauls
>

Wow this is not actually the case presented in y first post, but still 
very interesting.