bnf.bnf

/**
 * BNF grammar grammar.
 *
 * A BNF parser generated from it can parse its own grammar.
 *
 * Example:
 *
 *   ./bin/syntax -g examples/bnf.g -f examples/bnf.bnf -m slr1
 */

%%

Spec
              : OptModInc '%%' ProductionList
                  { return $$ = {bnf: $3, moduleInclude: $1 }; }
              ;

OptModInc
              : MODULE_INCLUDE
                  { $$ = $1; }
              |
              ;

ProductionList
              : ProductionList Production
                  { $$ = $1; $$[$2[0]] = $2[1]; }

              | Production
                  { $$ = {}; $$[$1[0]] = $1[1]; }
              ;

Production
              : LHS ':' HandleList ';'
                  { $$ = [$1, $3]; }
              ;

LHS
              : ID
                  { $$ = yytext; }
              ;

HandleList
              : HandleList '|' HandleAction
                  { $$ = $1; $$.push($3); }

              | HandleAction
                  { $$ = [$1]; }
              ;

HandleAction
              : Handle Action
                  { $$ = [$1, $2]; }
              ;

Handle
              : Entries
                  { $$ = $1; }
              |
                  { $$ = ''; }
              ;


Entries
              : Entries Entry
                  { $$ = $1 + ' ' + $2; }

              | Entry
                  { $$ = $1; }
              ;

Entry
              : ID
                  { $$ = yytext; }

              | STRING
                  { $$ = yytext; }
              ;

Action
              : CODE
                  { $$ = yytext; }
              |
                  { $$ = null; }
              ;