//
// mjava.grammar
// To build:
//      java -jar sablecc.jar mjava.grammar
//      javac Main.java
//

Helpers
   digit = ['0'..'9'];
   let   = ['a'..'z'] | ['A'..'Z'];
   space = ' ' | 9;
   newline = 10 | 11 | 12;
   not_star = [0..41] | [43..127];
   not_slash = [0..46] | [48..127];
   not_slashstar = [0..41] | [43..46] | [48..127];
   not_newline = [0..9] | [11..127];

Tokens

   // TODO: add missing tokens according to Appendix A and B

   boolean = 'boolean';
   class_token = 'class'; // must not be "class" - that conflicts with Java keywords
   else = 'else';
   extends = 'extends';
   false = 'false';
   if = 'if';
   int = 'int';
   length = 'length';
   main = 'main';
   new = 'new';
   println = 'System.out.println';
   public = 'public';
   return = 'return';
   static = 'static';
   string = 'String';
   this = 'this';
   true = 'true';
   void = 'void';
   while = 'while';

   lbracket = '[';
   rbracket = ']';
   lbrace = '{';
   rbrace = '}';
   lparen = '(';
   rparen = ')';
   semi = ';';
   equal = '=';
   dot = '.';
   bang = '!';
   comma = ',';
   plus = '+';
   and = '&&';
   less = '<';
   minus = '-';
   star = '*';

   // TODO: complete the following to define tokens for identifiers, numbers,
   //   whitespace, single-line comments starting with '//', and multi-line
   //   comments starting with /* and ending with */
   id = let;
   number = digit;
   whitespace = (space | newline)*;
   line_comment = '//' newline ;
   slashstar_comment = '/*' ;

Ignored Tokens
   whitespace,
   line_comment,
   slashstar_comment;

Productions

   program        = main_class class_decl*
                  ;
   main_class     = class_token id lbrace main_def rbrace
                  ;
   main_def       = public static void main
                    lparen string lbracket rbracket id rparen
                    lbrace statement rbrace
                  ;
   class_decl     = {baseclass} class_token id lbrace var_decl* method_decl*
                    rbrace
                  | {extclass}  class_token [classid]:id extends [baseid]:id
                    lbrace var_decl* method_decl* rbrace
                  ;
   var_decl       = type id semi
                  ;
   method_decl    = public type id lparen formal_list rparen method_body
                  ;
   method_body    = lbrace var_decl* statement* return exp semi rbrace
                  ;
   formal_list    = {empty}
                  | {nonempty} type id formal_rest
                  ;
   formal_rest    = {empty}
                  | {nonempty} comma type id formal_rest
                  ;
   type           = {array} int lbracket rbracket
                  | {bool}  boolean
                  | {int}   int
                  | {class} id
                  ;
   statement      = {ifone} if lparen exp rparen statement
                  | {if} if lparen exp rparen [truepart]:stmt_all_paired
                    else [falsepart]:statement
                  | {while} while lparen exp rparen statement
                  | {simple} simple_stmt
                  ;
   simple_stmt    = {print} println lparen exp rparen semi
                  | {assign} id equal exp semi
                  | {array}  id lbracket [index]:exp rbracket equal exp semi
                  | {nested} lbrace statement* rbrace
                  ;
   stmt_all_paired= {sans_trailer} simple_stmt
                  | {while} while lparen exp rparen stmt_all_paired
                  | {if} if lparen exp rparen [truepart]:stmt_all_paired
                         else [falsepart]:stmt_all_paired
                  ;
   exp            = and_exp
                  ;
   and_exp        = {simple} comparison
                  | {and} [left]:and_exp and [right]:comparison
                  ;
   comparison     = {simple} arith_exp
                  | {compare} [left]:arith_exp less [right]:arith_exp
                  ;
   arith_exp      = {simple} term
                  | {add} [left]:arith_exp plus [right]:term
                  | {subt} [left]:arith_exp minus [right]:term
                  ;
   term           = {simple} bool_exp
                  | {times} [left]:term star [right]:bool_exp
                  ;
   bool_exp       = {simple} factor
                  | {not} bang bool_exp
                  ;
   factor         = {array} factor lbracket [index]:exp rbracket
                  | {length} factor dot length
                  | {call} factor dot id lparen exp_list rparen
                  | {num}  number
                  | {true} true
                  | {false} false
                  | {id} id
                  | {this} this
                  | {newarray} new int lbracket exp rbracket
                  | {newobj}   new id lparen rparen
                  | {nested}   lparen exp rparen
                  ;
   exp_list       = {empty}
                  | {exps} exp exp_rest
                  ;
   exp_rest       = {empty}
                  | {exps} comma exp exp_rest
                  ;