Re: scaning from memory

[John W. Millaway]

> I am trying to write a parser with flex/bison scaning strings
> in memory, but I can't make it work. I am pretty sure it's a
> common way of using flex, but I didn't find any example on the
> web. (I have read the manual, of course). I have found several
> times this question, but no answer.
> I don't know where to put the yy_scan_string() statement. I
> use the <<EOF>> rule as last rule. And I have also modified
> the prototype of the yylex function with
> #define YY_DECL int yylex(YYSTYPE *lvalp,char *name)
> where name is the string I want to parse.

You should call yy_scan_string before calling yylex. Here are two examples:

1. In general:

  YY_BUFFER_STATE buf_state = yy_scan_string( str );
  while( yylex() != 0 )
      ;
  yy_delete_buffer(buf_state);


2. Your particular scanner:

%{
#define YY_USER_INIT  buf_state = yy_scan_string( name );
%}
%%
    static YY_BUFFER_STATE buf_state;

<<EOF>>   { yy_buffer_delete( buf_state ); yyterminate(); }
%%

-John


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