Weird problem

[Valentin Tolmer]

Hello everyone,

I'm working on an addition to bison, and I have a small grammar problem...
I added something to the bison grammar, to understand statements such as
%prec OR '+' > '*'  (for example)

However when parsing a statement with several tokens as char, I have a 
problem. The example I'm currently testing with is this:

%prec '^' > OR '*' '/' '-' '+'

which is read to me, for some reason, as
%prec '+' > OR '+' '+' '+' '+'

What I mean is that every char is correctly read, the symbols are the 
right ones, but somehow when creating the list, it screws up and 
replaces every char with the last one read (not just +, the last one 
read). I test the lists at the beginning of declare_precedence_relation, 
so none of my outside code affects it.

Here's the code, in parse-gram.y (the printf displays the right characters):


precedence_relation_declaration:
  "%prec" precedence_relation_symbols precedence_relation_comparator
    precedence_relation_symbols
    { declare_precedence_relation ($2, $4, $3); }
;

precedence_relation_symbols:
  precedence_symbol { $$ = $1; }
| precedence_relation_symbols precedence_symbol
    { $$ = symbol_list_append ($1, $2); }
;

precedence_symbol:
  string_or_id
  {
    if (is_prec_group ($1))
      $$ = expand_symbol_group (symgroup_from_uniqstr($1, &@1), @1); 
//not called in this example
    else
      $$ = symbol_list_sym_new (symbol_from_uniqstr ($1, @1), @1);
  }
| CHAR
  {
    printf ("char seen : %s\n", symbol_from_uniqstr(char_name ($1), 
@1)->tag);
    $$ = symbol_list_sym_new (symbol_from_uniqstr (char_name ($1), @1), 
@1);
  }
;

string_or_id:
  STRING { $$ = uniqstr_new (quotearg_style (c_quoting_style, $1)); } 
//not called, I believe, in that example
| ID { $$ = $1; }
;

precedence_relation_comparator:
  ">"     { $$ = prec_superior; }
| "="     { $$ = prec_equal; }
| ">" ">" { $$ = prec_superior_strict; }
;