Grammar for the PL= language in Jison

pl0_wikip.jison

%token IDENT CONST VAR PROCEDURE COMPARISON expression NUMBER
%token CALL BEGIN END IF THEN WHILE DO ODD

%%
program
    : block "."
    ;

block
    : const var procedure statement
    ;

const
    : /* empty */
    | CONST IDENT "=" NUMBER ";" const
    ;

var
    : /* empty */
    | VAR identlist ";" var
    ;

identlist
    : IDENT
    | identlist "," IDENT
    ;

procedure
     : /* empty */
     | PROCEDURE IDENT ";" block ";" procedure
     ;

statement
     : IDENT ":=" expression
     | CALL IDENT
     | BEGIN statements END
     | IF condition THEN statement
     | WHILE condition DO statement
     ;

statements
     : statement
     | statement ";" statements
     ;

condition
     : ODD expression
     | expression COMPARISON  expression
     ;

/* expression as in the calculator example */