Re: [Cppcms-users] Questions about decode UTF-8 to Unicode code point

[陈抒 <csf...@gm...>]

Thanks. It's one of switch statments, I learned it but never used this way
- 'without break'.
 http://msdn.microsoft.com/en-us/library/k0t5wee3.aspx


Dean Chen
Best regards
http://blog.csdn.net/sheismylife


On Thu, Jun 13, 2013 at 3:12 AM, Marcel Hellwig <ke...@co...> wrote:

>  On 12.06.2013 15:55, 陈抒 wrote:
>
> Another question, when looking into the codes of utf.hpp, I find the
> following codes for case 3, 2, 1 are  identical, why?
>
>
> 00213             code_point <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a068111a6b9d6d465a63893ed5c05e2f8> c = lead & ((1<<(6-trail_size))-1);00214 00215             // Read the rest00216             unsigned char tmp;00217             switch(trail_size) {00218             case 3:00219                 if(BOOST_LOCALE_UNLIKELY(p==e))00220                     return incomplete <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a20dbe458fd18229a0e6c09888d031b38>;00221                 tmp = *p++;00222                 if (!is_trail <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/structboost_1_1locale_1_1utf_1_1utf__traits.html#ae2cb78fcb8a58bed3e0ce1d6528a719a>(tmp))00223                     return illegal <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a30010000878c7732340bda8956b844fb>;00224                 c = (c << 6) | ( tmp & 0x3F);00225             case 2:00226                 if(BOOST_LOCALE_UNLIKELY(p==e))00227                     return incomplete <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a20dbe458fd18229a0e6c09888d031b38>;00228                 tmp = *p++;00229                 if (!is_trail <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/structboost_1_1locale_1_1utf_1_1utf__traits.html#ae2cb78fcb8a58bed3e0ce1d6528a719a>(tmp))00230                     return illegal <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a30010000878c7732340bda8956b844fb>;00231                 c = (c << 6) | ( tmp & 0x3F);00232             case 1:00233                 if(BOOST_LOCALE_UNLIKELY(p==e))00234                     return incomplete <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a20dbe458fd18229a0e6c09888d031b38>;00235                 tmp = *p++;00236                 if (!is_trail <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/structboost_1_1locale_1_1utf_1_1utf__traits.html#ae2cb78fcb8a58bed3e0ce1d6528a719a>(tmp))00237                     return illegal <http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/namespaceboost_1_1locale_1_1utf.html#a30010000878c7732340bda8956b844fb>;00238                 c = (c << 6) | ( tmp & 0x3F);00239             }
>
>
>  Please note, that there is no break after a case, but rather a
> fallthrough. It's not optimal to produce the code three times, but its
> valid. Maybe a for/while loop is better here.
>
>
>
>
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