Added the options --unused-token <token> and --unused-tokens.

CHANGES

+2015/07/20:
+Added the command line options --unused-token <symbol> and --unused-tokens.
+
 2015/06/29:
 Changed the treatment of the positional keywords $i. They are now
 rewritten into variables of the form '_i' where 'i' is an integer.

TODO

@@ -104,10 +104,6 @@
   le cours de compilation où on démarre avec une grammaire à trous),
   par exemple les non-terminaux inaccessibles
 
-* add a way of turning off the "unused token" warning for a specific token
-  (or for all of them) This is legitimate because the lexer might be designed
-  to produce certain tokens that the parser does not use at all.
-
 * move to a new license (GPL V2?), as per Hongbo Zhang's request.
 * Les fichiers dans demos/ ne devraient pas être sous QPL mais libres...
 

doc/macros.tex

@@ -109,6 +109,8 @@
 \newcommand{\oexternaltokens}{\texttt{-{}-external-tokens}\xspace}
 \newcommand{\ofixedexc}{\texttt{-{}-fixed-exception}\xspace}
 \newcommand{\ograph}{\texttt{-{}-graph}\xspace}
+\newcommand{\oignoreone}{\texttt{-{}-unused-token}\xspace}
+\newcommand{\oignoreall}{\texttt{-{}-unused-tokens}\xspace}
 \newcommand{\oinfer}{\texttt{-{}-infer}\xspace}
 \newcommand{\ointerpret}{\texttt{-{}-interpret}\xspace}
 \newcommand{\ointerpretshowcst}{\texttt{-{}-interpret-show-cst}\xspace}

doc/main.tex

@@ -156,6 +156,13 @@ vertices are the grammar's nonterminal symbols. There is a directed edge from
 vertex $A$ to vertex $B$ if the definition of $A$ refers to $B$. The file is
 in a format that is suitable for processing by the \emph{graphviz} toolkit.
 
+\docswitch{\oignoreone \nt{symbol}} This switch suppresses the warning that
+is normally emitted when \menhir finds that the terminal symbol \nt{symbol} is
+unused.
+
+\docswitch{\oignoreall} This switch suppresses all of the warnings that are
+normally emitted when \menhir finds that some terminal symbols are unused.
+
 \docswitch{\oinfer} This switch causes the semantic actions to be checked for
 type consistency \emph{before} the parser is generated. This is done by
 invoking the \ocaml compiler. Use of \oinfer is \textbf{strongly recommended},

src/partialGrammar.ml

@@ -717,13 +717,15 @@ let check_parameterized_grammar_is_well_defined grammar =
       ) grammar.p_rules;
     
   (* Check that every token is used. *)
-  begin match Settings.token_type_mode with
+  if not Settings.ignore_all_unused_tokens then begin
+    match Settings.token_type_mode with
     | Settings.TokenTypeOnly ->
         ()
     | Settings.TokenTypeAndCode
     | Settings.CodeOnly _ ->
         StringMap.iter (fun token { tk_position = p } -> 
-	if not (StringSet.mem token !used_tokens) then
+          if not (StringSet.mem token !used_tokens
+               || StringSet.mem token Settings.ignored_unused_tokens) then
             Error.warning [p] 
               (Printf.sprintf "the token %s is unused." token)
         ) grammar.p_tokens

src/settings.ml

@@ -159,6 +159,15 @@ type suggestion =
 let suggestion =
   ref SuggestNothing
 
+let ignored_unused_tokens =
+  ref StringSet.empty
+
+let ignore_unused_token t =
+  ignored_unused_tokens := StringSet.add t !ignored_unused_tokens
+
+let ignore_all_unused_tokens =
+  ref false
+
 let options = Arg.align [
   "--base", Arg.Set_string base, "<basename> Specifies a base name for the output file(s)";
   "--canonical", Arg.Unit (fun () -> construction_mode := ModeCanonical), " Construct a canonical Knuth LR(1) automaton";
@@ -208,6 +217,8 @@ let options = Arg.align [
   "--table", Arg.Set table, " Use the table-based back-end";
   "--timings", Arg.Set timings, " Display internal timings";
   "--trace", Arg.Set trace, " Include tracing instructions in the generated code";
+  "--unused-token", Arg.String ignore_unused_token, "<token> Do not warn that <token> is unused";
+  "--unused-tokens", Arg.Set ignore_all_unused_tokens, " Do not warn about any unused token";
   "--version", Arg.Set version, " Show version number and exit";
   "-b", Arg.Set_string base, "<basename> Synonymous with --base <basename>";
   "-lg", Arg.Set_int logG, " Synonymous with --log-grammar";
@@ -389,3 +400,8 @@ let strict =
 let fixedexc =
   !fixedexc
 
+let ignored_unused_tokens =
+  !ignored_unused_tokens
+
+let ignore_all_unused_tokens =
+  !ignore_all_unused_tokens

src/settings.mli

@@ -163,3 +163,13 @@ val strict: bool
 
 val fixedexc: bool
 
+(* This is a set of tokens which may be unused and about which we should not
+   emit a warning. *)
+
+val ignored_unused_tokens: StringSet.t
+
+(* This flag supersedes the set [ignored_unused_tokens]. If it is set, then
+   we should not emit a warning about any unused tokens. *)
+
+val ignore_all_unused_tokens: bool
+