Flex 文件中的“未声明的标识符”错误

Question

trying to create a simple compiler using flex/bison but i keep getting "undeclared identifier" error messages from scanner.l for each one of the identifiers that I want returned I get these error messages when running bison in parser.y:

---

Parser.y:73.10-14: symbol Class is used, but is not defined as a token and has no rules

Parser.y:74.34-36: symbol Eof is used, but is not defined as a token and has no rules

Parser.y:74.23-26: symbol Decl is used, but is not defined as a token and has no rules

Parser.y:83.33-36: symbol Type is used, but is not defined as a token and has no rules

Parser.y:88.32-39: symbol Variable is used, but is not defined as a token and has no rules

Parser.y:91.25-32: symbol Argument is used, but is not defined as a token and has no rules

---

scanner.l (flex/lexical analyzer)

%{
#include <iostream>
using std::cout;
using std::endl;
#include "parser.h"
extern "C" int isatty(int);

int col=1;
int lin=1;
%}

%x Comment

%%
[/][/].*\n    {lin++; col = 1;}

"int"         {col += yyleng; return INTEGER;}

"boolean"     {col += yyleng; return BOOL;}

"double"      {col += yyleng; return DOUBLE;}

"null"        {col += yyleng; return NULLVAL;}

"if"          {col += yyleng; return IF;}

"else"        {col += yyleng; return ELSE;}

"while"       {col += yyleng; return WHILE;}

"for"         {col += yyleng; return FOR;}

"true"        {col += yyleng; return TRUEFALSE;}

"false"       {col += yyleng; return TRUEFALSE;}

"class"       {col += yyleng; return CLASS;}

"return"      {col += yyleng; return RETURN;}

"new"         {col += yyleng; return NEW;}

"static"      {col += yyleng; return STATIC;}

"private"     {col += yyleng; return PRIVATE;}

"this"        {col += yyleng; return THIS;}

"extends"     {col += yyleng; return EXTENDS;}

"instanceof"  {col += yyleng; return INSTANCEOF;} 

"-"           {col += yyleng; return SUB;}

"+"           {col += yyleng; return ADD;} 

"/"           {col += yyleng; return DIV;} 

"*"           {col += yyleng; return MUL;} 

"%"           {col += yyleng; return MOD;}

"="           {col += yyleng; return *yytext;}

"++"          {col += yyleng; return INC;}

"--"          {col += yyleng; return DEC;}

"=="          {col += yyleng; return EQ;}

"<"           {col += yyleng; return SM;}

">"           {col += yyleng; return GR;}

"<="          {col += yyleng; return SME;}

">="          {col += yyleng; return GRE;}

"!"           {col += yyleng; return NEGATION;}

"&&"          {col += yyleng; return AND;}

"||"          {col += yyleng; return OR;}

[a-zA-Z_][a-zA-Z_0-9]*  {col += yyleng; return ID;}

0|([1-9][0-9]*)         {col += yyleng; return NUMBER;}

([0-9]+[\.][0-9]*([eE][-+]?[0-9]+)?) {col += yyleng; return REAL;}


[\t]*       {col += 4*yyleng;}

[ ]*        {col += yyleng;}

[\n]        {col =1; lin++;}

[\(\)\,\{\};=]          {
                            col += yyleng;
                            return *yytext;
                        }
"/*"      { 
            BEGIN(Comment);
          }
<Comment>"*/" { 
            BEGIN(INITIAL);
          }
<Comment>\n   { col = 1; lin++; }
<Comment>.    { col += yyleng; }
.                       {
                        col += yyleng;
                        }
%%

int yywrap()
{
return 0;
}

int main()
{
yylex();
return 0;
}

parser.y (bison syntax analyzer)

%{
  #include<iostream>  
  using std::cout;
  using std::endl;
  #include "parser.h"
  extern int lin;
  extern int col;
  int Errs = 0;


  extern int yylex();
  extern int yyerror(const char *);
  extern int yydebug;
  extern char* yytext;
  extern int yyleng;
  extern int errors;
  extern int yywrap();
 
  #define YYDEBUG 1
%}
%debug

%token          INTEGER
%token          BOOL
%token          DOUBLE
%token          NULLVAL
%token          IF
%token          ELSE
%token          WHILE
%token          FOR
%token          TRUEFALSE
%token          CLASS
%token          RETURN
%token          NEW
%token          STATIC
%token          PRIVATE
%token          THIS
%token          EXTENDS
%token          INSTANCEOF
%token          SUB
%token          ADD
%token          DIV
%token          MUL
%token          MOD
%token          INC
%token          DEC
%token          EQ
%token          SM
%token          GR
%token          SME
%token          GRE
%token          NEGATION
%token          AND
%token          OR
%token          ID
%token          NUMBER
%token          REAL



%nonassoc IfStatmentPrec
%nonassoc ELSE
%nonassoc EQ NEQ SM GR GRE SME 
    
%right      '='

%left        ADD SUB MUL DIV MODULE AND OR NEGATION POS NEG 



%start File
%%
File    :Class
        |File Decl Class Eof
        ;
CONSTRUCTOR:            
                | PRIVATE

            | STATIC
            
          ;

VARIABLES:          Type  '(' Arguments ')' '{' Insts '}' 
        ;
Insts :         Insts   Inst
             |   
             ;
Variables    :   Variables ',' Variable
            |    Variable   
            ;
Arguments   :   Argument
            |   Arguments ',' Argument
        ;
EmptyExpression :    
                |   Expression 
                ;
Inst    :    Expression ';'
            |'{' Insts '}'
            |WHILE '(' Expression ')' Inst
            |Type Variables ';'
            |IF '(' Expression ')' Inst %prec IfStatmentPrec
            |IF '(' Expression ')' Inst ELSE Inst
            |FOR '(' Type ID '=' Expression ';' EmptyExpression ';' EmptyExpression ')' Inst
                |
            |RETURN'(' Expression ')' Inst
            |Type Variables ';'
            |INSTANCEOF'(' Expression ')' Inst
            |Type Variables ';'
                        ';'
        
Expression  : 
        |   TRUEFALSE 
        |   BOOL  
        |   REAL 
        |   NULLVAL
        |   INTEGER
        |   REAL
        |   THIS
        |   SUB Expression  %prec NEG  
        |   Expression ADD Expression
        |   Expression SUB Expression  
        |   Expression DIV Expression
        |   Expression MUL Expression
        |   Expression MODULE Expression
        |   NEGATION Expression
        |   ID INC
        |   ID DEC
        |   ID '=' Expression 
        |   Expression EQ Expression
        |   Expression NEQ Expression
        |   Expression SM Expression
        |   Expression SME Expression
        |   Expression GR Expression
        |   Expression GRE  Expression
        |   Expression AND Expression
        |   Expression OR   Expression
        |   '(' Expression ')'
        ;



%%


int yyerror(const char* er)
{
cout<<"error in line: " <<lin << " at column "<<col<<" \n";
Errs += 1;
return 1;
}

Answer 1

Token "CLASS" is defined as uppercase, so you need to write it that way. Other identifiers are not even declared.