How to create a simple calculator for sum two numbers using flex, bison and cmake? – Debian

how to create a simple calculator for sum two numbers using flex, bison and cmake?
i try understand flex and bison (studying both), I still don’t know how to use them, and I would like a practical example of how to compile (with cmake) a simple project for me to study.

I found an example calculator and an example from cmake, but I can’t compile to test and be able to study and understand. Below has a failed attempt to compile.

This code is available in GitHub

using

find_package (BISON REQUIRED)
find_package (FLEX REQUIRED)

flex_target
bison_target

CMakeFiles.txt

cmake_minimum_required(VERSION 3.7)
project(lesson)


set(CMAKE_CXX_STANDARD 11)
set(CMAKE_INCLUDE_CURRENT_DIR ON)

find_package(BISON REQUIRED)
find_package(FLEX REQUIRED)


bison_target(lesson-parser
        calc-parser.y
        ${CMAKE_CURRENT_BINARY_DIR}/parser.tab.cpp
        )

flex_target(lesson-scanner
        calc-scanner.l
        ${CMAKE_CURRENT_BINARY_DIR}/scanner.tab.cpp
        )
add_executable(lesson ${BISON_MyParser_OUTPUTS} ${FLEX_MyScanner_OUTPUTS} main.cpp)
add_flex_bison_dependency(lesson-scanner lesson-parser)

calc-parser.y

/* Gramatica: {Vt, Vn, P, S}
 * Vt = {INTEGER, NEWLINE, +, -, *, /, (, )}
 * Vn = {line, term, expr}
 * P = {
 *      line -> epsilon
 *      line -> term
 *      term -> newline
 *      term -> expr newline
 *      expr -> intnumer
 *      expr -> expr + expr
 *      expr -> expr - expr
 *      expr -> expr * expr
 *      expr -> expr / expr
 *      expr -> (expr)
 *      expr -> -expr
 *     }
 * S = line
 */

%{
#include <stdio.h>
int intval;
extern char *yytext;
%}


%token INTEGER, NEWLINE

%left '+' '-'
%left '*' '/'
%nonassoc UMINUS

%start line   /* simbolo sentencial */

%%
line:
    | line term
    ;

term: NEWLINE
    | expr NEWLINE   {printf("%dn", $1);}
    | error NEWLINE  {yyerror;}
    ;

expr: INTEGER {$$ = intval;}
     | expr '+' expr  {$$ = $1 + $3;}
     | expr '-' expr  {$$ = $1 - $3;}
     | expr '*' expr  {$$ = $1 * $3;}
     | expr '/' expr  {if($3) $$ = $1 / $3;
                       else {
                             printf("Divide by zero");
                             yyerror;
                            }
                      }
     | '(' expr ')' {$$ = $2;}
     | '-' expr %prec UMINUS {$$ = - $2;}
     ;

%%

yyerror(s)
char *s;
{
printf("Oops: %s at symbol %cn", s, yytext[0]);
}

calc-scanner.l

%{
#include "y.tab.h"
extern int intval;
%}
integer [0-9]+
nl      n

%%
[ t]+  ;
{integer}    {sscanf(yytext, "%d", &intval);  return INTEGER;}
{nl}         {return NEWLINE;}
.            {return yytext[0];}
%%

Parser.h

#ifndef LESSON_PARSER_H
#define LESSON_PARSER_H

namespace Test {

    class Parser {
    public:
        static int parser();
    };
}

#endif //LESSON_PARSER_H

Parser.cpp

#include "Parser.h"

int Test::Parser::parser() {
    return yyparse();
}

main.cpp

#include <iostream>
#include "Parser.h"

int main(int argc, char **argv) {
    return Test::Parser::parser();
}

I try call the "Test::Parser::parser()" to analyze the input.
The compiler log error is:

====================[ Build | all | Debug-Debian ]==============================
/usr/bin/cmake --build /tmp/tmp.SIGMymeLDv/cmake-build-debug-debian --target all -- -j 4
[ 66%] Building CXX object CMakeFiles/lesson.dir/Parser.cpp.o
[ 66%] Building CXX object CMakeFiles/lesson.dir/main.cpp.o
/tmp/tmp.SIGMymeLDv/Parser.cpp: In static member function 'static int Test::Parser::parser()':
/tmp/tmp.SIGMymeLDv/Parser.cpp:8:12: error: 'yyparse' was not declared in this scope
     return yyparse();
            ^~~~~~~
/tmp/tmp.SIGMymeLDv/Parser.cpp:8:12: note: suggested alternative: 'parser'
     return yyparse();
            ^~~~~~~
            parser
make[2]: *** [CMakeFiles/lesson.dir/build.make:76: CMakeFiles/lesson.dir/Parser.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:73: CMakeFiles/lesson.dir/all] Error 2
make: *** [Makefile:84: all] Error 2