如何將指數運算符的支持添加到boost :: spirit計算器之一中？

Question

我想將這個指數運算符添加到這個boost :: spirit計算器example，其語法如下。請注意，像「-2^2^3」這樣的表達式必須被解析爲「 - （2 ^（2^3））」== -256。

expr = 
     equality_expr.alias() 
     ; 

    equality_expr = 
      relational_expr 
     >> *(equality_op > relational_expr) 
     ; 

    relational_expr = 
      logical_expr 
     >> *(relational_op > logical_expr) 
     ; 

    logical_expr = 
      additive_expr 
     >> *(logical_op > additive_expr) 
     ; 

    additive_expr = 
      multiplicative_expr 
     >> *(additive_op > multiplicative_expr) 
     ; 

    multiplicative_expr = 
      unary_expr 
     >> *(multiplicative_op > unary_expr) 
     ; 

    unary_expr = 
      primary_expr 
     | (unary_op > primary_expr) 
     ; 

    primary_expr = 
      uint_ 
     | identifier 
     | bool_ 
     | '(' > expr > ')' 
     ; 

    identifier = 
      !keywords 
     >> raw[lexeme[(alpha | '_') >> *(alnum | '_')]] 
     ; 

已經閱讀文檔後，我的理解是，我要插入以下exponential_expr規則的語法爲它用正確的從右到左結合解析指數運算：

multiplicative_expr = 
      exponential_expr 
     >> *(multiplicative_op > exponential_expr) 
     ; 

    exponential_expr = 
      unary_expr 
     >> !(exponential_op >> exponential_expr) 
     ; 

凡規則是：

qi::rule<Iterator, ast::expression(), ascii::space_type> 
    expr, equality_expr, relational_expr, 
    logical_expr, additive_expr, multiplicative_expr, exponential_expr 
    ; 

    qi::rule<Iterator, ast::operand(), ascii::space_type> 
    unary_expr, primary_expr 
    ; 

    qi::rule<Iterator, ast::function_call(), ascii::space_type > 
    function_call 
    ; 

    qi::rule<Iterator, std::list<ast::expression>(), ascii::space_type > 
    argument_list 
    ; 

    qi::rule<Iterator, std::string(), ascii::space_type> 
    identifier 
    ; 

    qi::symbols<char, ast::optoken> 
    equality_op, relational_op, logical_op, 
    additive_op, multiplicative_op, unary_op, exponential_op 
    ; 

    qi::symbols<char> 
    keywords 
    ; 

我現在遇到的問題是，該方案無法編譯，因爲AST（ast.hpp）必須是我也相應地進行了修改，但我現在不完全如此。你有什麼主意嗎？

這是編譯器錯誤：

calculator/ExpressionDef.hpp:114:9: required from 'calculator::parser::expression::expression(calculator::error_handler&) [with Iterator = __gnu_cxx::__normal_iterator >]' Expression.cpp:4:37: required from here /usr/include/boost/spirit/home/qi/detail/assign_to.hpp:152:13: error: no matching function for call to 'calculator::ast::expression::expression(const boost::variant, boost::recursive_wrapper, boost::recursive_wrapper >&)' /usr/include/boost/spirit/home/qi/detail/assign_to.hpp:152:13: note: candidates are: In file included from ./calculator/Expression.hpp:20:0, from calculator/ExpressionDef.hpp:1, from Expression.cpp:1: ./calculator/Ast.hpp:83:12: note: calculator::ast::expression::expression() ./calculator/Ast.hpp:83:12: note: candidate expects 0 arguments, 1 provided ./calculator/Ast.hpp:83:12: note: calculator::ast::expression::expression(const calculator::ast::expression&) ./calculator/Ast.hpp:83:12: note: no known conversion for argument 1 from 'const boost::variant, boost::recursive_wrapper, boost::recursive_wrapper >' to 'const calculator::ast::expression&' ./calculator/Ast.hpp:83:12: note: calculator::ast::expression::expression(calculator::ast::expression&&) ./calculator/Ast.hpp:83:12: note: no known conversion for argument 1 from 'const boost::variant, boost::recursive_wrapper, boost::recursive_wrapper >' to 'calculator::ast::expression&&'

Answer 1

我還沒有徹底的測試，但我認爲，以下修改提供你想要的功能。請記住，此版本的計算器使用整數作爲其唯一類型，因此您將無法使用負指數並存在溢出危險。

1. ast.hpp
   你需要一個新的元素（op_exp）添加到枚舉optoken：

   ... 
   op_times, 
   op_divides, 
   op_exp, //ADDED //Line 55 
   op_positive, 
   ... 
   

2. expression.hpp
   您需要添加的聲明對於exponential_expr,exponential_operand和exponential_op：

   qi::rule<Iterator, ast::expression(), ascii::space_type> 
       expr, equality_expr, relational_expr, 
       logical_expr, additive_expr, multiplicative_expr, exponential_expr //MODIFIED 
       ; 
   
   qi::rule<Iterator, ast::operand(), ascii::space_type> 
       unary_expr, primary_expr, exponential_operand //MODIFIED 
       ; 
   ... 
   qi::symbols<char, ast::optoken> 
       equality_op, relational_op, logical_op, 
       additive_op, multiplicative_op, exponential_op, unary_op //MODIFIED 
       ; 
   

3. expression_def.hpp
   您需要添加的初始化exponential_op，改變規則如下，並添加新的規則的BOOST_SPIRIT_DEBUG_NODES名單：

   ... 
   multiplicative_op.add 
       ("*", ast::op_times) 
       ("/", ast::op_divide) 
       ;  
   exponential_op.add  //ADDED //Line 69 
   ("^", ast::op_exp) 
   ; 
   ... 
   multiplicative_expr =  
        unary_expr 
       >> *(multiplicative_op > unary_expr) 
       ; 
   
   unary_expr = //MODIFIED 
        exponential_operand 
       | (unary_op > exponential_operand) 
       ; 
   
   exponential_operand = exponential_expr; //ADDED 
   
   exponential_expr =   //ADDED 
        primary_expr 
       >> *(exponential_op > unary_expr) 
       ; 
   
   primary_expr = 
        uint_ 
       | identifier 
       | bool_ 
       | '(' > expr > ')' 
       ; 
   ... 
   (additive_expr) 
   (multiplicative_expr) 
   (exponential_expr)  //ADDED //Line 150 
   (exponential_operand) //ADDED 
   (unary_expr) 
   ... 
   

4. 編譯.cpp
   您需要將新案例添加到program::print_assembler和compiler::operator()中的交換機：

   ... 
   case op_div: 
       line += "  op_div"; 
       break; 
   
   case op_exp:  //ADDED //Line 105 
       line += "  op_exp"; 
       break; 
   
   case op_eq: 
       line += "  op_eq"; 
       break; 
   ... 
   case ast::op_times: program.op(op_mul); break; 
   case ast::op_divide: program.op(op_div); break; 
   case ast::op_exp: program.op(op_exp); break; //ADDED //Line 244 
   
   case ast::op_equal: program.op(op_eq); break; 
   ... 
   

5. vm.hpp
   你需要一個新的元素（op_exp）添加到枚舉byte_code：

   ... 
   op_mul,   // multiply top two stack entries 
   op_div,   // divide top two stack entries 
   op_exp,   //ADDED //Line 24 
   
   op_not,   // boolean negate the top stack entry 
   ... 
   

6. VM。CPP
   你需要一個新的情況vmachine::execute添加到交換機（我只是用的std ::戰俘，包括以前CMATH）：

   ... 
   case op_div: 
       --stack_ptr; 
       stack_ptr[-1] /= stack_ptr[0]; 
       break; 
   
   case op_exp: //ADDED //Line 60 
       --stack_ptr; 
       stack_ptr[-1] = std::pow(stack_ptr[-1],stack_ptr[0]); 
       break; 
   
   case op_eq: 
       --stack_ptr; 
       stack_ptr[-1] = bool(stack_ptr[-1] == stack_ptr[0]); 
       break; 
   ...