Question

please provide good explanation.

Consider the following grammar for variable and class declarations in Java:

      <Decl>      -> <VarDecl>
                   | <ClassDecl>

      <VarDecl>   -> <Modifiers> <Type> <VarDec> SEM

      <ClassDecl> -> <Modifiers> CLASS ID LBRACE <DeclList> RBRACE

      <DeclList>  -> <Decl>
                   | <DeclList> <Decl>

      <VarDec>    -> ID
                   | ID ASSIGN <Exp>

                   | <VarDec> COMMA ID
                   | <VarDec> COMMA ID ASSIGN <Exp>

Indicate any problems in this grammar that prevent it from being parsed by a recursive-descent parser with one token lookahead. You can simply circle the offending parts of the grammar above.

Transform the rules for <Decl> and <DeclList> so they can be parsed by a recursive-descent parser with one token lookahead (you don’t need to transform the rules for <VarDec>). I.e., remove any left-recursion and left-factor the grammar. Make as few changes to the grammar as possible, but do not use Extended BNF. The nonterminals <Decl> and <DeclList> of the modified grammar should describe the same language as the original nonterminals.

3. (25 pts) Consider the following grammar for variable and class declarations in Java: <Decl> -<VarDecl> <VarDec1〉 -> <Modifiers> <Type> <VarDee> SEM <ClassDecl> -> <Modifiers» CLASS ID LBRACE <DeclList> RBRACE <VarDec> ->ID ID ASSIGN <Exp> | <VarDec> COMMA ID ASSIGN <Exp> Indicate any problems in this grammar that prevent it from being parsed by a recursive-descent parser with one token lookahead. You can simply circle the offending parts of the grammar above. Transform the rules for <Decl> and <DeclList> so they can be parsed by a recursive-descent parser with one token lookahead (you don't need to transform the rules for <VarDec>). Le., remove any left-recursion and left-factor the grammar. Make as few changes to the grammar as possible, but do not use Extended BNF. The nonterminals <Decl> and <Decllist> of the modified grammar should describe the same language as the original nonterminals.

Answer 1