Semantic actions on Menhir

Question

I am building a small compiler for an assignment language.

Consider the following rule:

var_block : 
  | LPAREN var_decl+ RPAREN { var_scope := var_scope + 1 };

Is the semantic action triggered when var_block is first recognized or is it triggered once the end of the production is reached (in this case, RPAREN)?

Answer 1

Your question is exactly why you shouldn't do this.

Don't do side-effect which are order-sensitive in production rules. Productions rules should be used to build up a data structure that represent your program. Once this is done, you can analyze/execute/whatever it.

Answer 2

在读取整个作品后将触发该事件。