exprtk_simple_example_24.cpp File Reference

#include <cstdio>
#include <string>
#include "exprtk.hpp"

Include dependency graph for exprtk_simple_example_24.cpp:

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Classes
struct	char_process< T, Process >

Functions
template<typename T >
T	is_digit_func (const unsigned char c)
template<typename T >
T	to_num_func (const unsigned char c)
template<typename T >
void	rpn_example ()
int	main ()

Function Documentation

is_digit_func()

template<typename T >

T is_digit_func

(

const unsigned char

c

)

Definition at line 48 of file exprtk_simple_example_24.cpp.

{
   return (('0' <= c) && (c <= '9')) ? T(1) : T(0);
}

main()

int main

(

)

Definition at line 139 of file exprtk_simple_example_24.cpp.

{
   rpn_example<double>();
   return 0;
}

rpn_example()

template<typename T >

void rpn_example

(

)

Definition at line 60 of file exprtk_simple_example_24.cpp.

{
   typedef exprtk::symbol_table<T> symbol_table_t;
   typedef exprtk::expression<T>   expression_t;
   typedef exprtk::parser<T>       parser_t;
 
   const std::string rpn_program =
      " var stack[1000] := [0];                                                   "
      " var stack_size  := 0;                                                     "
      "                                                                           "
      " for (var i := 0; i < rpn_expression[]; i += 1)                            "
      " {                                                                         "
      "    var c := rpn_expression[i : i + 1];                                    "
      "                                                                           "
      "    if (c == ' ')                                                          "
      "    {                                                                      "
      "       continue;                                                           "
      "    }                                                                      "
      "    else if (is_digit(c))                                                  "
      "    {                                                                      "
      "       stack[stack_size] := to_num(c);                                     "
      "       stack_size        += 1;                                             "
      "    }                                                                      "
      "    else                                                                   "
      "    {                                                                      "
      "       var operator := c;                                                  "
      "       var operand1 := stack[stack_size - 2];                              "
      "       var operand2 := stack[stack_size - 1];                              "
      "       stack_size   -= 2;                                                  "
      "                                                                           "
      "       switch                                                              "
      "       {                                                                   "
      "          case operator == '+' : stack[stack_size] := operand1 + operand2; "
      "          case operator == '-' : stack[stack_size] := operand1 - operand2; "
      "          case operator == '*' : stack[stack_size] := operand1 * operand2; "
      "          case operator == '/' : stack[stack_size] := operand1 / operand2; "
      "          case operator == '^' : stack[stack_size] := operand1 ^ operand2; "
      "       };                                                                  "
      "                                                                           "
      "       stack_size += 1;                                                    "
      "    }                                                                      "
      " };                                                                        "
      "                                                                           "
      " println(stack[0], ' = ', rpn_expression);                                 "
      "                                                                           ";
 
   std::string rpn_expression;
 
   char_process<T,is_digit_func<T>> isdigit;
   char_process<T,to_num_func<T>>   tonum;
   exprtk::rtl::io::println<T>      println;
 
   symbol_table_t symbol_table;
   symbol_table.add_stringvar("rpn_expression", rpn_expression);
   symbol_table.add_function ("println"       , println       );
   symbol_table.add_function ("is_digit"      , isdigit       );
   symbol_table.add_function ("to_num"        , tonum         );
 
   expression_t expression;
   expression.register_symbol_table(symbol_table);
 
   parser_t parser;
   parser.compile(rpn_program, expression);
 
   const std::string rpn_expressions[] =
   {
      "2 3 8 / ^ 4 6 * + 3 9 / -", // 2 ^ (3 / 8) + 4 * 6 - 3 / 9
      "1 2 / 6 5 2 - / * 7 +"    , // (1 / 2) * (6 / (5 - 2)) + 7
      "1 2 * 3 / 4 * 5 / 6 *"    , // ((((1 * 2) / 3) * 4) / 5) * 6
      "8 6 4 + * 2 /"              // (8 * (6 + 4)) / 2
   };
 
   for (std::size_t i = 0; i < sizeof(rpn_expressions) / sizeof(std::string); ++i)
   {
      rpn_expression = rpn_expressions[i];
      expression.value();
   }
}

to_num_func()

template<typename T >

T to_num_func

(

const unsigned char

c

)

Definition at line 54 of file exprtk_simple_example_24.cpp.

{
   return static_cast<T>(c - '0');
}