Nullable nonterminals:

  (grammar | grammar_rest | item_rest | terms_rest)


The starters of nonterminals:

grammar ->
  (LANG | LBRACKET)
grammar_rest ->
  (BLANK)
production ->
  (LANG | LBRACKET)
ordinary_production ->
  (LANG)
non_token_production ->
  (LBRACKET)
terms ->
  (LANG | STRING | TILDA)
terms_rest ->
  (VBAR)
term ->
  (LANG | STRING | TILDA)
item_rest ->
  (LANG | STRING | TILDA)
item ->
  (LANG | STRING | TILDA)


The followers of nullable nonterminals:

grammar ->
  ($END)
grammar_rest ->
  ($END)
terms_rest ->
  ($END | BLANK)
item_rest ->
  ($END | BLANK | VBAR)


*** Annotated grammar ***

#grammar
: ($END)
     /* empty */
| (LANG | LBRACKET)
     production #grammar_rest 
;

#grammar_rest
: ($END)
     /* empty */
| (BLANK)
     BLANK #grammar 
;

production
: (LANG)
     ordinary_production 
| (LBRACKET)
     non_token_production 
;

ordinary_production
: (LANG)
     LANG IDENTIFIER RANG TO terms 
;

non_token_production
: (LBRACKET)
     LBRACKET IDENTIFIER RBRACKET TO terms 
;

terms
: (LANG | STRING | TILDA)
     term #terms_rest 
;

#terms_rest
: ($END | BLANK)
     /* empty */
| (VBAR)
     VBAR terms 
;

term
: (LANG | STRING | TILDA)
     item #item_rest 
;

#item_rest
: ($END | BLANK | VBAR)
     /* empty */
| (LANG | STRING | TILDA)
     term 
;

item
: (TILDA)
     TILDA 
| (LANG)
     LANG IDENTIFIER RANG 
| (STRING)
     STRING 
;