/*
 * call-seq:
 *    res[ n ] -> Hash
 *
 * Returns tuple _n_ as a hash. 
 */
static VALUE
pgresult_aref(VALUE self, VALUE index)
{
        PGresult *result = get_pgresult(self);
        int tuple_num = NUM2INT(index);
        int field_num;
        VALUE fname,val;
        VALUE tuple;

        if ( tuple_num < 0 || tuple_num >= PQntuples(result) )
                rb_raise( rb_eIndexError, "Index %d is out of range", tuple_num );

        tuple = rb_hash_new();
        for ( field_num = 0; field_num < PQnfields(result); field_num++ ) {
                fname = rb_tainted_str_new2( PQfname(result,field_num) );
                ASSOCIATE_INDEX(fname, self);
                if ( PQgetisnull(result, tuple_num, field_num) ) {
                        rb_hash_aset( tuple, fname, Qnil );
                }
                else {
                        val = rb_tainted_str_new( PQgetvalue(result, tuple_num, field_num ),
                                                  PQgetlength(result, tuple_num, field_num) );

                        /* associate client encoding for text format only */
                        if ( 0 == PQfformat(result, field_num) ) {
                                ASSOCIATE_INDEX( val, self );
                        } else {
#ifdef M17N_SUPPORTED
                                rb_enc_associate( val, rb_ascii8bit_encoding() );
#endif
                        }
                        rb_hash_aset( tuple, fname, val );
                }
        }
        return tuple;
}