/*
 * 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;
}