[GSOC] regular expressions beta is here

[Dmitry Olshansky]

On 17.08.2011 3:47, bearophile wrote:
> Dmitry Olshansky:
>
>>> To get a small no-crap-included beta package see download section of
>>> https://github.com/blackwhale/FReD for .7zs.
> I have not patched DMD, but it gives me some problem here:
>
> void parseFlags(S)(S flags)
> {
>      foreach(ch; flags)//flags are ASCII anyway
>      {
>          switch(ch)
>          {
>
>              foreach(i, op; __traits(allMembers, RegexOption))
>              {
>                  case RegexOptionNames[i]:
>                          if(re_flags&  mixin("RegexOption."~op))
>                              throw new RegexException(text("redundant flag specified: ",ch));
>                          re_flags |= mixin("RegexOption."~op);
>                          break;
>              }
>              default:
>                  if(__ctfe)
>                     assert(text("unknown regex flag '",ch,"'"));
>                  else
>                      new RegexException(text("unknown regex flag '",ch,"'"));
>          }
>
>
> To better see the situation I have written a small test case:
>
> import std.typetuple: TypeTuple;
>
> enum RegexOption : uint { A, B, C } // no need to put a semicolon here
>
> alias TypeTuple!(RegexOption.A, RegexOption.B, RegexOption.C) RegexOptionNames;
>
> void main() {
>      RegexOption ch;
>
>      switch (ch) {
>          foreach (i, op; __traits(allMembers, RegexOption))
>              case RegexOptionNames[i]: break;
>
>          default: assert(0);
>      }
> }
>
>
> test.d(12): Error: switch case fallthrough - use 'goto case;' if intended
> test.d(12): Error: switch case fallthrough - use 'goto case;' if intended
> test.d(12): Error: switch case fallthrough - use 'goto case;' if intended
> test.d(14): Error: switch case fallthrough - use 'goto default;' if intended
>
> This used to work, I think. The new DMD switch analysis seems to have a bug.
>
> -------------
Yes, that's a bug. But it's not a regression, I assume you started to 
compile with -w, that's when it happens IIRC. I almost forgot about it, 
thanks for uncovering it again, you may as well file it.

>
> If you want a benchmark, to compare it with other implementations, there is this one:
> http://shootout.alioth.debian.org/debian/program.php?test=regexdna&lang=gdc&id=4
>
>
All in due time, though this one involves semi-fixed patterns, hm ... 
very promising.

-- 
Dmitry Olshansky