Context Free Grammar: <program> -><stmtlist>\'end\' <stmtlist> -><stmt><stmtlist

Question

 Context Free Grammar: <program> -><stmtlist>'end' <stmtlist>        -><stmt><stmtlist>|                     ----- note: this is equivalent to <stmt>|<stmt><stmtlist>      <stmt>            -> ID '=' <expr>                 |'read' ID                 |'write' <expr> <expr>            -> <term> {('+'|'-')<term>} <term>            -> <factor> {('*'|'/') <factor>} <factor>  -> ID                 | INT_CONSTANT                 |'('<expr>')'  The possible set of tokens, represented with regular expressions, includes:  ASSIGN  -> =  PLUS    -> + MINUS   -> - TIMES   -> * DIV     -> /  LPAREN  ->( RPAREN  -> ) ID      -> letter(letter|digit)*         Except read, write, and end. INT_CONSTANT    -> digit digit*  LETTER          ->[a-zA-Z] DIGIT           ->[0-9]   Your task is to implement a scanner and a parser for this simple language.(in any programming language of your choice.) 

Explanation / Answer

Program -> ClassDeclList ClassDecl -> class id { VarDeclList MethodDeclList } VarDecl -> Type id ; MethodDecl -> Type id ( FormalList ) { VarDeclList StmtList return Exp ; } Formal -> Type id Type -> int [ ] | boolean | int | id Stmt -> { StmtList } | if ( Exp ) Stmt else Stmt | while ( Exp ) Stmt | System.out.println ( Exp ) ; | id = Exp ; | id [ Exp ] = Exp ; Exp -> Exp Op Exp | Exp [ Exp ] | Exp . length | Exp . id ( ExpList ) | integer | true | false | id | this | new int [ Exp ] | new id ( ) | ! Exp | ( Exp ) Op -> && | < | + | - | * ExpList -> Exp ExpRest | ExpRest -> , Exp ExpRest | FormalList -> Type id FormalRest | FormalRest -> , Type id FormalRest | ClassDeclList = ClassDeclList VarDecl | MethodDeclList = MethodDeclList MethodDecl | VarDeclList = VarDeclList VarDecl |

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