/// Decodes the syntax of an XPath expression. On entry, the lexical analysis has already
/// produced a list of basic tokens.
/// \n Throws : syntax_error, syntax_overflow
void token_syntax_decoder::v_syntax_decode ()
{
bool o_res;
// group double tokens ('!=', '::', ...)
v_tokenize_expression ();
// reset list start
v_set_current_top ();
u_nb_recurs = 0;
// the XPath expression, well, ..., must be an xpath_expr
o_res = o_recognize (xpath_expr, true);
if (! o_res)
throw syntax_error ("main level");
#ifdef DUMP_SYNTAX
if (ltp_get (0))
printf ("!!! Still to decode : %s !!!\n", cp_disp_class_lex (ltp_get (0) -> lex_get_value ()));
else
printf ("Completely parsed\n");
printf ("%d recursions\n", u_nb_recurs);
#endif
}
/// Decodes an XPath expression, further manipulating a token list
/// \n On input, we have a list of basic lexical tokens. We only merge here the
/// multiple tokens : like '::' or '!='. We also delete whitespace tokens
void token_list::v_tokenize_expression ()
{
v_set_current_top ();
while (ltp_get (1))
{
switch (ltp_get (0) -> lex_get_value ())
{
case lex_colon :
if (ltp_get (1) -> lex_get_value () == lex_colon)
{
v_replace_current (lex_2_colon, "::");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_slash :
if (ltp_get (1) -> lex_get_value () == lex_slash)
{
v_replace_current (lex_2_slash, "//");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_exclam :
if (ltp_get (1) -> lex_get_value () == lex_equal)
{
v_replace_current (lex_not_equal, "!=");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_lt :
if (ltp_get (1) -> lex_get_value () == lex_equal)
{
v_replace_current (lex_lt_equal, "<=");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_gt :
if (ltp_get (1) -> lex_get_value () == lex_equal)
{
v_replace_current (lex_gt_equal, ">=");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_dot :
if (ltp_get (1) -> lex_get_value () == lex_dot)
{
v_replace_current (lex_2_dot, "..");
v_delete_next ();
}
else
v_inc_current (1);
break;
case lex_space :
v_delete_current ();
break;
default :
v_inc_current (1);
break;
} // switch
} // while
}