<span>option c++
%option noyywrap
 
</span>{
#include <sstream>
#include <cstdlib>
#include "parser.h"
using namespace std;
<span>}
 
<span class="caps">DIGIT</span>   [0-9]
DIGIT1  [1-9]
 
</span>%
 
{DIGIT1}{DIGIT}*  {
                   cout << "Lexer: " << yytext << endl;
                   return Parser::NUMBER;
                  }
 
.                 {
                   return Parser::UNKNOWN;
                  }
 
<<<span class="caps">EOF</span>>>           {
                   yyterminate();
                  }
%%

<span>name Parser
%define <span class="caps">LSP</span>_NEEDED
%define <span class="caps">MEMBERS</span>                 \
    virtual ~Parser()   {} \
    private:                   \
       yyFlexLexer lexer;
%define <span class="caps">LEX</span>_BODY {return lexer.yylex();}
 
%define <span class="caps">ERROR</span>_BODY {cerr << "error encountered at line: "<<lexer.lineno()<<" last word parsed:"<<lexer.YYText()<<"\n";}
 
%header{
#include < ostream >
#include < fstream >
#include < FlexLexer.h >
using namespace std;
</span>}
 
<span>union {
       int i_type;
}
 
%token <span class="caps">UNKNOWN</span>
%token < i_type > <span class="caps">NUMBER</span>
 
%type < i_type > number
 
%start number
 
</span>%
number
 
: <span class="caps">NUMBER</span> { $$ = atoi(lexer.YYText()); cout << "Parser value " << $$ << endl;}
 
;
 
%%

#include "parser.h"
#include < iostream >
using namespace std;
 
int main(int argc, char ** argv)
{
       Parser parser;
       parser.yyparse();
       return 0;
}

all: test
 
parser.cc: parser.y
        bison++ -d -hparser.h -o $@ $<
 
scanner.cc: scanner.l
        flex++ -d -o$@ $<
 
test:  parser.o scanner.o test.o
        g++ -o $@ test.o parser.o scanner.o
 
clean:
        $(RM) *~ *# test *.o *.h
        $(RM) parser.cc scanner.cc