Re: Simple parsing problem

Eric Fowler wrote:
> I am writing a bison grammar to parse strings coming from various
> kinds of attached devices.
>
> One of the strings is of the form:
> $FOO,field1,field2, 0,a,1,b,3,c, ....<CRLF>
>
>
> where there are a variable number of paired fields of the form
> <number> COMMA <text> COMMA. The comma is always a delimiter here,
> the text contains no commas.


How about:
%token COMMA ","
%token FOO CRLF field1 field2
%token NUMBER LETTER
%%
item:
      FOO "," field1 "," field2 "," sequence "," CRLF
;


sequence:
            /* empty */
      | sequence NUMBER "," LETTER
;
%%


If the last LETTER of a "sequence" should not have a terminating ",",
delete it from the "item" grammar variable. If sequence must be
non-empty, replace the empty rule by 'NUMBER "," LETTER'. (field1 and
field2 tokens here only to make the snippet Bison-compilable.)


      Hans

Return to the comp.compilers page.
Search the comp.compilers archives again.