token value return in custom yylex()

[Bernd Prager]

Hi,
I would appreciate some help, where I can't find the right info
in the manual.

In order to do some character escaping (and because my scanner is
really not that difficult) I wrote a custom yylex(). Everything seems to
be according to the manual, but the token value gets messed up in the
recursive grammar I use. (It works fine when I test my grammar with a flex.)
Can somebody tell me what I'm missing here?

Here is my code:
----------- snip --------------------
%{
#include <stdio.h>
#include <string.h>
#include "parser.tab.h"

#define TESTSTRING "word1 word2" // testpattern

char *data, buffer[1024];
%}

%union {
    int id;
    char *str;
}

%type <str> object token list
%token <id> WORD

%start object
%%

object: token
       {
          printf( "object: (token >%s<)\n", $1);
          strcpy($$, $1);
       }
    |  list
       {
          printf ("object: (list >%s<)\n", $1);
          strcpy($$, $1);
       }
    ;

/* a single word */
token:  WORD
       {
          printf( "word: >%s<\n", $1);
          strcpy($$, (char *)$1);
       }
    ;

list:   token object
       {
          char buf[1024];
          printf( "term: (single >%s< object >%s<)\n", $1, $2);
          sprintf($$, "%s %s", $1, $2);
       }
    ;

%%
char *delimiters = "_,()' ";

char *lexbuffer;
char *clone;
char *yytext;
int length;

int main()
{
  int i;

  /* allocate memory for string lexbuffers */
  length = strlen(TESTSTRING) + 1;
  lexbuffer = (char *)malloc( length );
  yytext = (char *)malloc( length );
  strcpy( lexbuffer, TESTSTRING );
  clone = lexbuffer;

  i = yyparse();

  free( lexbuffer );
  free( yytext );
  return i;
}

int yylex()
{
   int i;

   if (clone >= lexbuffer + length) return 0;           // end of string

   while (clone[0] == ' ' || clone[0] == '\t') clone++; // skip white space

   if (strchr(delimiters, clone[0])!=NULL) {            // character literal
      i = clone[0];
      clone++;
      return i;
   }

   yylval.str = yytext;
   for (i = 0; (i<length) && (strchr(delimiters, clone[0])==NULL); i++) {
      if (clone[0] == '\\') {   // escape next character
        clone++;
      }
      yytext[i] = clone[0];
      clone++;
   }
   yytext[i] = 0;               // terminate yytext WORD
   return WORD;
}
----------- snip --------------------

Here's the output with flex:
----------- snip --------------------
token: >word1<
token: >word2<
object: (token>word2<)
list: (token>word1< object >word2<)
object: (list>word1 word2<)
----------- snip --------------------

Here's mine:
----------- snip --------------------
token: >word1<
token: >word2<
object: (token >word2<)
list: (token >word2< object >word2<)
object: (list >word2 word2 <)
Segmentation fault
----------- snip --------------------

Thanks for any help.
-- Bernd