1
我正在閱讀LFS並遇到bison我在其他地方看過它,所以我想我應該多瞭解一些。我發現this page from UC Riverside CS department和示例代碼不起作用。任何人都知道最新錯誤?爲方便起見,我貼的代碼:Bison示例代碼沒有編譯
calc.lex文件:
/* Mini Calculator */
/* calc.lex */
%{
#include "heading.h"
#include "tok.h"
int yyerror(char *s);
int yylineno = 1;
%}
digit [0-9]
int_const {digit}+
%%
{int_const} { yylval.int_val = atoi(yytext); return INTEGER_LITERAL; }
"+" { yylval.op_val = new std::string(yytext); return PLUS; }
"*" { yylval.op_val = new std::string(yytext); return MULT; }
[ \t]* {}
[\n] { yylineno++; }
. { std::cerr << "SCANNER "; yyerror(""); exit(1); }
calc.y文件:
/* Mini Calculator */
/* calc.y */
%{
#include "heading.h"
int yyerror(char *s);
int yylex(void);
%}
%union{
int int_val;
string* op_val;
}
%start input
%token <int_val> INTEGER_LITERAL
%type <int_val> exp
%left PLUS
%left MULT
%%
input: /* empty */
| exp { cout << "Result: " << $1 << endl; }
;
exp: INTEGER_LITERAL { $$ = $1; }
| exp PLUS exp { $$ = $1 + $3; }
| exp MULT exp { $$ = $1 * $3; }
;
%%
int yyerror(string s)
{
extern int yylineno; // defined and maintained in lex.c
extern char *yytext; // defined and maintained in lex.c
cerr << "ERROR: " << s << " at symbol \"" << yytext;
cerr << "\" on line " << yylineno << endl;
exit(1);
}
int yyerror(char *s)
{
return yyerror(string(s));
}
這裏是錯誤消息:
$ make
bison -d -v calc.y
cp calc.tab.c bison.c
cmp -s calc.tab.h tok.h || cp calc.tab.h tok.h
g++ -g -Wall -ansi -pedantic -c bison.c -o bison.o
calc.tab.c: In function ‘int yyparse()’:
calc.tab.c:1381: warning: deprecated conversion from string constant to ‘char*’
calc.tab.c:1524: warning: deprecated conversion from string constant to ‘char*’
flex calc.lex
cp lex.yy.c lex.c
g++ -g -Wall -ansi -pedantic -c lex.c -o lex.o
calc.lex:8: error: redefinition of ‘int yylineno’
lex.yy.c:349: error: ‘int yylineno’ previously defined here
calc.lex: In function ‘int yylex()’:
calc.lex:23: warning: deprecated conversion from string constant to ‘char*’
lex.yy.c: At global scope:
lex.yy.c:1105: warning: ‘void yyunput(int, char*)’ defined but not used
make: *** [lex.o] Error 1