c 中的 (f)lex 和 C++ 中的 bison/yacc

Question

我正在尝试构建一种迷你编程语言，例如 ruby 和 flex/bison。如果 Flex 和 bison 都是用 C 编写的，那么它可以很好地协同工作。当我需要 c++ 为我的非终端（expr、语句等）构建 classes 时，问题就开始了。

mRuby.l:

%option yylineno

%{
#include "absyn.h"
#include "mRuby.tab.h"

int line_nr = 1;
int col_nr = 1; 

/*
col_nr += strlen(atoi(yytext));
*/

%}

identifier  [A-z]([A-z]|[0-9])*
integer  -?([0-9])+(_?[0-9])*
comment  ("#".*"\n")
whitespace (" "|"\t")+
boolean (true|false)
CR (\r\n)*|(\n)*|(\r)*


%%
";"                     { return SEMICOLON; }
"undef"                 { return UNDEF; }
"def"                   { return DEF; }
"("                     { return LPAREN; }
")"                     { return RPAREN; }
"end"                   { return END;}
"return"                { return RETURN;}
"if"                    { return IF; }
"then"                  { return THEN; }
"elsif"                 { return ELSIF;}
"else"                  { return ELSE; }
"unless"                { return UNLESS; }
"while"                 { return WHILE; }
"do"                    { return DO; }
"until"                 { return UNTIL; }
"case"                  { return CASE; }
"when"                  { return WHEN; }
","                     { return COMMA; }
"="                     { return ASSIGN; }
"+="                    { return PLUSASSIGN; }
"-="                    { return MINUSASSIGN; }
"*="                    { return MULASSIGN; }
"/="                    { return DIVASSIGN; }
"&&="                   { return ANDASSIGN; }
"||="                   { return ORASSIGN; }
"+"                     { return PLUS; }
"-"                     { return MINUS; }
"*"                     { return MUL; }
"/"                     { return DIV; }
">"                     { return GT; }
">="                    { return GE; }
"<"                     { return LT; }
"<="                    { return LE; }
"=="                    { return EQ; }
"!="                    { return NE; }
"&&"                    { return AND; }
"||"                    { return OR; }
"!"                     { return NOT; }
"\n"                    { col_nr = 1; return SEMICOLON; }
{boolean}               { return BOOLEAN; }  
{comment}|{whitespace}  { /* doe niets */ }
{integer}               {

                        return INTEGER; 
                        }
{identifier}            { 
                        char* s = (char*) malloc(yyleng+1);
                        strcpy(s, yytext);
                        
                        return IDENTIFIER;
                        }

.      {
  if (yytext[0] < ' '){ 
    /* non-printable char */
    /*yyerror*/ 
    fprintf(stderr,"illegal character: ^%c",yytext[0] + '@'); 
  }
  else {
    if (yytext[0] > '~') {
      /* non-printable char printed as octal int padded with zeros, eg 2*/
      /*yyerror(*/
      fprintf(stderr,"illegal character: \%03o", (int) yytext[0]);
    }
    else {
      /*dit is een functie verwijder enter om te gebruiken*/
      /*yyerror(*/
      fprintf(stderr,"illegal character: %s",yytext);
    }
  }
  /* lex read exactly one char; the illegal one */
  //fprintf(stderr," at line %d column %d\n", line_nr, (col_nr-1));
  fprintf(stderr," at line %d column %d\n", yylineno, (col_nr-1));
                   }
%%

/* Function called by (f)lex when EOF is read. If yywrap returns a
   true (non-zero) (f)lex will terminate and continue otherwise.*/
int yywrap(){
  return (1);
}

我的野牛档案：

%{
#include "lexer.h"
#include "absyn.h"
#include <iostream>


void yyerror(const char* str);

int main(int argc, char* argv[]){
  int tokenid;
  std::cout << "Hello world! \n";

  //return yyparse();
  yyparse();

  std::cout << "TEST \n";
  return 0;
}

%}

%union {
  int g;
  char* id;
  char* b;
  Stmts stmts;
  Stmt stmt;
  CaseStmt casestmt;
  WhenStmt whenstmt;
  IfStmt ifstmt; 
  ElifStmt elifstmt;
  Expr expr;
  Exprs exprs;
  ArgList arglist;
  ArgLists arglists;
  Ids ids;
  T t;
  Assignop assignop;
  Binop binop;
}
// vul aan met tokendeclaraties

%token
 SEMICOLON UNDEF DEF LPAREN RPAREN END RETURN INTEGER
 IF THEN ELSIF ELSE UNLESS WHILE DO UNTIL CASE WHEN COMMA
 ASSIGN PLUSASSIGN MINUSASSIGN MULASSIGN DIVASSIGN ANDASSIGN ORASSIGN
 PLUS MINUS MUL DIV GT GE LT LE EQ NE AND OR NOT

%token <id> IDENTIFIER
%token <b> BOOLEAN

%type <stmts> stmts
%type <stmt> stmt
%type <casestmt> casestmt
%type <whenstm> whenstmt
%type <ifstmt> ifstmt
%type <elifstm> elifstmt
%type <expr> expr
%type <exprs> exprs
%type <arglist> arglist
%type <arglists> arglists
%type <ids> ids
%type <t> t 
%type <assignop> assignop


%type <binop> binop
%type <binop> PLUS

 // vul aan met voorrangdeclaraties
%nonassoc operation
%nonassoc expression

%nonassoc OR NE EQ LT LE GT GE AND

%left PLUS MINUS
%left TIMES DIVIDES
%right ASSOP
%right UNOT
%right UMINUS
//%defines

%%

// vul aan met producties
program   : compstmt            { std::cout << "program 0"; }
;

compstmt  : stmts              { std::cout << " compstmt 1"; }
          | stmts t            { std::cout << " compstmt 2"; }
;

stmts     : stmt               { std::cout << " stmts 1"; }
          | stmts t stmt       { std::cout << " stmts 2 "; }
;

stmt      : undefstmt     { std::cout << " stmt 1"; }
          | expr          { std::cout << " stmt 2"; }
          | defstmt       { std::cout << " stmt 3"; }
          | returnstmt    { std::cout << "stmt 4"; }
          | ifstmt        { std::cout << "stmt 5"; }
          | whilestmt     { std::cout << " stmt 6"; }
          | untilstmt     { std::cout << " stmt 7"; }
          | unlessstmt    { std::cout << " stmt 8"; }
          | casestmt      { std::cout << " stmt 9"; }
          | error         { std::cout << " error"; }
;

undefstmt : UNDEF IDENTIFIER                                      { std::cout << " undefstmt"; }
;

defstmt   : DEF IDENTIFIER LPAREN arglists RPAREN compstmt END    { std::cout << " defstmt"; }
;

returnstmt : RETURN expr                                          { std::cout << " returnstmt"; }
;

whilestmt : WHILE expr DO compstmt END                            { std::cout << " whilestmt"; }
;

untilstmt : UNTIL expr DO compstmt END                            { std::cout << " untilstmt"; }
;

unlessstmt  : UNLESS expr THEN compstmt END                         { std::cout << " unless 1"; }
            | UNLESS expr THEN compstmt ELSE compstmt END           { std::cout << " unless 2"; }
;

casestmt  : CASE expr WHEN expr THEN compstmt END                         { std::cout << " casestmt "; }
          | CASE expr WHEN expr THEN compstmt ELSE compstmt END           { std::cout << " casestmt "; }
          | CASE expr WHEN expr THEN compstmt whenstmt END                { std::cout << " casestmt "; }
          | CASE expr WHEN expr THEN compstmt whenstmt ELSE compstmt END  { std::cout << " casestmt "; }
;
whenstmt  : WHEN expr THEN compstmt                           { std::cout << " whenstmt "; }
          | whenstmt WHEN expr THEN compstmt                  { std::cout << " whenstmt "; }
;
ifstmt    : IF expr THEN compstmt END                         { std::cout << "ifstmt"; }
          | IF expr THEN compstmt ELSE compstmt END           { std::cout << "ifstmt"; }
          | IF expr THEN compstmt elifstmt END                { std::cout << "ifstmt"; }
          | IF expr THEN compstmt elifstmt ELSE compstmt END  { std::cout << "ifstmt"; }
;

elifstmt  : ELSIF expr THEN compstmt                { std::cout << " elifstmt "; }
          | elifstmt ELSIF expr THEN compstmt       { std::cout << " elifstmt "; }
;

expr      : IDENTIFIER                              { std::cout << " expr 1"; }
          | IDENTIFIER assignop expr %prec ASSOP    { std::cout << " expr 2"; }
          | NOT expr %prec UNOT                     { std::cout << " expr 3"; }
          | BOOLEAN                                 { std::cout << " expr 4"; }
          | MINUS expr %prec UMINUS                 { std::cout << " expr 5"; }
          | IDENTIFIER LPAREN RPAREN                { std::cout << " expr 6"; }
          | IDENTIFIER LPAREN exprs RPAREN          { std::cout << " expr 7"; }
          | expr binop expr                         { std::cout << " expr 8"; }
;

exprs     : expr                      { std::cout << " exprs "; }
          | exprs COMMA expr          { std::cout << " exprs "; }
;

arglists  : arglist           { std::cout << " arglists "; }
          | arglists arglist  { std::cout << " arglists "; }
;

arglist   : IDENTIFIER        { std::cout << " arglist "; }
          | IDENTIFIER ids    { std::cout << " arglist "; }
;

ids       : SEMICOLON IDENTIFIER       { std::cout << " ids "; }
          | SEMICOLON IDENTIFIER ids   { std::cout << " ids "; }
;

t         : SEMICOLON     { std::cout << " t "; }
;

assignop  : ASSIGN        { std::cout << "assop" ; }
          | PLUSASSIGN    { std::cout << "assop" ; }
          | MINUSASSIGN   { std::cout << "assop" ; }
          | MULASSIGN     { std::cout << "assop" ; }
          | DIVASSIGN     { std::cout << "assop" ; }
          | ANDASSIGN     { }
          | ORASSIGN      { }
;

binop     : PLUS  { Binop op = ; $$ = op;  }
          | MINUS { std::cout << "expr MINUS expr\n"; }
          | MUL   { std::cout << "expr MUL expr\n"; }
          | DIV   { std::cout << "expr DIV expr\n"; }
          | LE    { std::cout << "expr LE expr\n"; }
          | LT    { std::cout << "expr LT expr\n"; }
          | GE    { std::cout << "expr GE expr\n"; }
          | GT    { std::cout << "expr GT expr\n"; }
          | EQ    { std::cout << "expr EQ expr\n"; }
          | NE    { std::cout << "expr NE expr\n"; }
          | AND   { std::cout << "expr AND expr\n"; }
          | OR    { std::cout << "expr OR expr\n"; }
;

%%

void yyerror (const char *s)
{
  // $$ = new OpExpr(, , );
  //std::cout << "%f\n",(+));
}

我尝试了多种混合包含和编译顺序的方法。我尝试编译所有内容的最新方法是这样的：

bison mRuby.yy
cp -R mRuby.yy mRuby.y
bison -d mRuby.y
flex mRuby.l
gcc -c lex.yy.c mRuby.tab.c  -ll -ly
g++ lex.yy.o -c
g++ mRuby.tab.cc -o parser

我的目标是用 class 构造替换 c++ 打印语句，以便在 c++ 中构建解析树和解释器。

Answer 1

Bison根据Bison manual, sec.9.
中写的原始文件的后缀生成带有后缀的文件如果你将 header 包含为 #include "mRuby.tab.h" 那么你的 bison 文件应该命名为 mRuby.y （如果你在 bison 中使用 c++，那么我建议使用像 .ypp 这样的 c++ 后缀，它将产生 .cpp和 .hpp 文件）。

生成文件：

flex mRuby.l
bison -d mRuby.y
g++ mRuby.tab.c lex.yy.c -o parser

似乎工作得很好，但如果 header 文件没有正确的类型定义，我很难检查。请注意，flex 和 bison 文件都以这种方式编译为 c++，这对 flex 和 bison 都很好。

此示例的 Bison 输出显示 18 shift/reduce 个冲突。

c 中的 (f)lex 和 C++ 中的 bison/yacc

(f)lex in c and bison/yacc in C++

c++

compiler-construction

yacc

bison

flex-lexer