Le 22 déc. 2013 à 21:17, Adam Smalin <acidzombi...@gmail.com> a écrit :
> > Please, post a self contained and minimal example.
>
> Ok. I didn't test it by parsing actual code. I only looked at the conflict
> %left ','
> %right '='
> %left '.'
>
> %%
>
> program:
> newline_many global_loop newline_many
> global_loop:
> global_expr
> | global_loop global_expr
> global_expr:
> VAR '(' ')' code_block
>
> code_block: '{' newline_many body newline_one_or_more '}'
>
> newline_many: | newline_many '\n'
> newline_one_or_more: '\n' | newline_one_or_more '\n'
> body:
> body_expr
> | body newline_one_or_more body_expr
> | body_expr '=' body_expr ',' body_expr %prec '.'
> | body_expr ',' body_expr '=' body_expr
> | body_expr ',' body_expr '=' body_expr ',' body_expr
> body_expr:
> body_expr '=' body_expr
> | body_expr '.' VAR
> | VAR
>
> %%
Honestly, I find your grammar hard to read. Plenty of
opportunities for ambiguities here, not just conflicts. It
shows a lot of redundancy, which calls for refactoring. Have
another look at my proposal with lvals and rvals.
> state 27
>
> 12 body: body_expr '=' body_expr . ',' body_expr
> 15 body_expr: body_expr . '=' body_expr
> 15 | body_expr '=' body_expr . [',', '\n']
> 16 | body_expr . '.' VAR
>
> '=' shift, and go to state 29
> '.' shift, and go to state 22
>
> $default reduce using rule 15 (body_expr)
>
> Conflict between rule 15 and token ',' resolved as reduce (',' < '=').
> Conflict between rule 15 and token '=' resolved as shift (%right '=').
> Conflict between rule 15 and token '.' resolved as shift ('=' < '.').
>
> As you can see it says "Conflict between rule 15 and token ',' resolved as
> reduce (',' < '=').". As you can see my rule is written as "| body_expr '='
> body_expr ',' body_expr %prec '.'"
You are referring to rule 12, bison is referring to rule 15.
Rule 15 has no explicit precedence token, so the last one is
issued, '=', whose precedence is greater than that of ','.
The output file includes:
0 $accept: program $end
1 program: newline_many global_loop newline_many
2 global_loop: global_expr
3 | global_loop global_expr
4 global_expr: "VAR" '(' ')' code_block
5 code_block: '{' newline_many body newline_one_or_more '}'
6 newline_many: %empty
7 | newline_many '\n'
8 newline_one_or_more: '\n'
9 | newline_one_or_more '\n'
10 body: body_expr
11 | body newline_one_or_more body_expr
12 | body_expr '=' body_expr ',' body_expr
13 | body_expr ',' body_expr '=' body_expr
14 | body_expr ',' body_expr '=' body_expr ',' body_expr
15 body_expr: body_expr '=' body_expr
16 | body_expr '.' "VAR"
17 | "VAR"
_______________________________________________
help-bison@gnu.org https://lists.gnu.org/mailman/listinfo/help-bison
