Irony: How to give KeyTerm precedence over variable?

Question

Relevant chunk of Irony grammar:

var VARIABLE = new RegexBasedTerminal("variable", @"(?-i)\$?\w+");

variable.Rule = VARIABLE;
tag_blk.Rule = html_tag_kw + attr_args_opt + block;
term_simple.Rule = NUMBER | STRING | variable | boolean | "null" | term_list;
term.Rule = term_simple | term_filter;
block.Rule = statement_list | statement | ";";
statement.Rule = tag_blk | directive_blk | term;

The problem is that both a "tag" and a "variable" can appear in the same place. I want my parser to prefer the tag over the variable, but it always prefers the variable. How can I change that?

I've tried changing tag_blk.Rule to PreferShiftHere() + html_tag_kw + attr_args_opt + block; and ImplyPrecedenceHere(-100) + html_tag_kw + attr_args_opt + block; but it doesn't help any. The parser doesn't even complain of an ambiguity.

Answer 1

Try changing the order of 'tag_blk.Rule' and 'variable.Rule' as tokenisers usually go after first match, and variable is first in your list.