[ragel-users] Problem with tag comment implementation

[Adrian Thurston]

Hi Hardik,

The problem here is very subtle. Conditions are executed before the 
actions on the same character, so the test of stringcmp is running 
before it is set. Change the embedding of tagend to a "to state" action 
using:

 >to(tagend)

That should do it.

-Adrian

Hardik Parikh wrote:
> Hi,
> 
>  
> 
>     I have requirement to consider following as valid comment in source 
> language
> 
>  
> 
>     |abc#
> 
>              Some description …….
> 
>    #abc|
> 
>  
> 
>   And following is invalid comment
> 
>  
> 
>     |abc#
> 
>              Some description …….
> 
>     #xyz|
> 
>  
> 
> And for above requirement I need to capture token string and performed 
> match operation as there is no inbuilt support for backward reference in 
> ragel
> 
> I tried out with following implementation
> 
>  
> 
> action mark_start{
> 
>      start = fpc+1;
> 
>     // printf(" Mark start at %c\n",fc);
> 
>   }
> 
>  action tagstart{
> 
>     size_t len = fpc - start ;
> 
>     s = calloc(len,sizeof(char));
> 
>     strncpy(s,start,len);
> 
>     s[len]='\0';
> 
>   //  printf("Start : %s\n",s);
> 
>   }
> 
>  
> 
>  action tagend{
> 
>     size_t len = fpc - start ;
> 
>     e = calloc(len,sizeof(char));
> 
>     strncpy(e,start,len);
> 
>     e[len]='\0';
> 
>    stringcmp = strncmp(e,s,sizeof(s));
> 
>     //printf("End : %s\n",e);
> 
>   }
> 
>  
> 
>    curl_tag_comment =
> 
>     '|'@mark_start (nonnewline - ws)* '#'@tagstart @comment(
> 
>       newline %{ entity = INTERNAL_NL; } %curl_ccallback
> 
>       |
> 
>       ws
> 
>       |
> 
>       (nonnewline - ws) @comment
> 
>     )* :>> ('#'@mark_start (nonnewline - ws)* '|' @tagend  when { 
> stringcmp == 0}) @comment;
> 
>  
> 
>  
> 
> Now I am able to capture both start and end substring properly and able 
> to do math operation in when condition but it produces as a valid commet 
> in parser for even a non valid statement.
> 
>  
> 
> Like
> 
>  
> 
> curl comment |abc#
> 
> curl comment             Some  description …….
> 
> curl comment  #xyz|
> 
>  
> 
> Please provide me any suggestions where I am doing something wrong or is 
> there any other better way to implement the same.
> 
>  
> 
> Thanks & Regards
> 
> Hardik Parikh
> 
>  
> 
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