Add @canonical tag

Author: trefis

src/octLexer.mll

@@ -638,6 +638,7 @@ let _ =
       ("see", fun lexbuf -> See (see lexbuf));
       ("since", fun lexbuf -> Since (version lexbuf));
       ("before", fun lexbuf -> Before (version lexbuf));
-      ("version", fun lexbuf -> Version (version lexbuf)); ]
+      ("version", fun lexbuf -> Version (version lexbuf));
+      ("canonical", fun lexbuf -> Canonical (identifier lexbuf)); ]
 
 }

src/octParser.mly

@@ -138,6 +138,7 @@ let html_close_to_string t = "</" ^ t ^ ">"
 %token RETURN
 %token INLINE
 %token <string> Custom
+%token <string> Canonical
 
 %token BEGIN
 %token END
@@ -213,6 +214,7 @@ tags:
 simple_tag:
 | Version           { Version $1 }
 | Since             { Since $1 }
+| Canonical         { Canonical $1 }
 ;
 
 text_tag:

src/octPrint.ml

@@ -169,6 +169,8 @@ let tag i ppf x =
   | Custom(s, txt) ->
       line i ppf "Custom %s\n" s;
       text i ppf txt
+  | Canonical s ->
+      line i ppf "Canonical %s" s
 
 let documentation i ppf (txt, tags) =
   line i ppf "Cinfo\n";

src/octTypes.mli

@@ -90,6 +90,7 @@ type tag =
   | Return_value of text (** \@return tag *)
   | Inline (** \@inline tag *)
   | Custom of string * text (** custom tag *)
+  | Canonical of string (** \@canonical tag *)
 
 (** A special comment *)
 type t = text * tag list