在 flex 和 bison 中忽略白色 space

Question

我正在尝试解析以下行：

BEGIN WRAP WIO3     
    NAME                            lgCell_prg160_io
    CONDITION                       UNI_PLACE_GLOBAL && compBits
ENDS WIO3

我用来解析以上行的语法正在解析到 UNI_PLACE_GLOBAL 然后它给出解析错误。

请帮我找出我犯的错误。

我认为它不接受 space 所以我怎样才能允许解析这些行？？

我完成了

lex.l

%{
#include <iostream>
#include <stdio.h>
const char s[2] = " ";
#include "yacca.tab.h"
char *token;
#define YY_DECL extern "C" int yylex()
int line_num = 1;

#ifdef DEBUG
#define RETURN(x)       cerr << "\n--> found " << #x << "\n"; return x;
#else
#define RETURN(x)       return x;
#endif


using namespace std;
%}

DOT             "."
COLON           ":"
SEMICOLON       ";"
COMMA           ","
ANGLE_LEFT      "<"
ANGLE_RIGHT     ">"
AT              "@"
EQUAL           "="
SQUARE_OPEN     "["
SQUARE_CLOSE    [^\]"]"
OPENBRACE       "\("
CLOSEBRACE      "\)"
QUOTE           "\""
QUOTE_OPEN      "\""
QUOTE_CLOSE     [^\]"\""
SPACE           " "
TAB             "\t"
CRLF            "\r\n"
QUOTED_PAIR     "\"[^\r\n]
DIGIT           [0-9]
ALPHA           [a-zA-Z]
QTEXT           [0-9a-zA-Z!#$%&'()*+,\-.\/:;<=>?@\[\]^_`{|}~""]

/* [ \t]         ; */


/* [ \s]         ; */



%%

[ \t]       ;

"//".*      /* ignore comments */

NAME          {  yylval.sval = strdup(yytext);
    return TOK_NAME; }

SIZE          { yylval.sval = strdup(yytext);
      return TOK_SIZE; }

ITERATE       { yylval.sval = strdup(yytext);
       return TOK_ITERATE; }

DIRECTION   { yylval.sval = strdup(yytext);
      return TOK_DIRECTION; }

STRAP       { yylval.sval = strdup(yytext);
      return TOK_STRAP; }

WRAP        { yylval.sval = strdup(yytext);
      return TOK_WRAP; }

VIA     { yylval.sval = strdup(yytext);
      return TOK_VIA; }

ENDS        { yylval.sval = strdup(yytext);
      return TOK_END; }

BEGIN       { yylval.sval = strdup(yytext);
      return TOK_BEGIN; }

BLOCK       { yylval.sval = strdup(yytext);
      return TOK_BLOCK; }

VERSION     { yylval.sval = strdup(yytext);
      return TOK_VERSION; }


STRUCTURE       { yylval.sval = strdup(yytext);
              return TOK_STRUCT; }

UNIQUE          { yylval.sval = strdup(yytext);
              return TOK_UNIQUE; }


REF         { yylval.sval = strdup(yytext);
              return TOK_REF; }

POSITION            { yylval.sval = strdup(yytext);
                  return TOK_POS; }

CONDITION           { yylval.sval = strdup(yytext);
                  return TOK_CON; }

ORIENTATION         { yylval.sval = strdup(yytext);
                  return TOK_ORI; }

{QTEXT}*        { yylval.sval = strdup(yytext);
          return TOK_STRING; } 


\\n            { printf("c> "); }      /* ignore line continuation */


^{CRLF}                         { return TOK_EMPTY_LINE; }
{CRLF}                          {}
.                               {}/* ignore unknown chars */
\n                      { ++line_num; /*RETURN(ENDL); */ }

yacc.y

%{
#include <cstdio> 
#include <cstring>
#include <iostream>
#include <stdio.h>

#define YYDEBUG 1

using namespace std;

extern "C" int yylex();
extern "C" FILE *yyin;
extern int line_num;


void yyerror(const char* s);
%}

// Symbols.
%union
{
    char* sval;
};

%token <sval> TOK_NAME
%token <sval> TOK_SIZE
%token <sval> TOK_STRING
%token <sval> TOK_ITERATE
%token <sval> TOK_DIRECTION
%token <sval> TOK_STRAP
%token <sval> TOK_WRAP
%token <sval> TOK_VIA
%token <sval> TOK_EMPTY_LINE 
%token <sval> TOK_BLOCK
%token <sval> TOK_LINE
%token <sval> TOK_BEGIN
%token <sval> TOK_END
%token <sval> TOK_VERSION
%token <sval> TOK_STRUCT
%token <sval> TOK_UNIQUE
%token <sval> TOK_REF
%token <sval> TOK_POS
%token <sval> TOK_CON
%token <sval> TOK_ORI
%token END ENDL




%%

language : program ;

program : block
| program block
;


block   : TOK_BEGIN TOK_BLOCK TOK_STRING blockcontents TOK_END TOK_STRING 
  {
    if (strcmp(,) == 0 )
    {
        printf("\nHEADER %s ",);
        printf("\nID %s ",);
    }
    else
    {
        printf("Block %s is not able to find its END\n" , );
    }

  }
  | TOK_BEGIN TOK_BLOCK TOK_STRING blockcontents TOK_END  { printf("Block %s is not able to find its END\n" , ); }

  | TOK_BEGIN TOK_STRING blockcontents TOK_END TOK_STRING {}
  | TOK_BEGIN TOK_STRUCT TOK_STRING blockcontents TOK_END TOK_STRING
  {
    if (strcmp(,) == 0 )
    {
        printf("\nHEADER %s ",);
        printf("\nID %s \n",);
    }
    else
    {
        printf("Block %s is not able to find its END\n" , );
    }

  }
  | TOK_BEGIN TOK_STRAP TOK_STRING blockcontents TOK_END TOK_STRING
  {
    if (strcmp(,) == 0 )
    {
        printf("\nHEADER %s ",);
        printf("\nID %s \n",);
    }
    else
    {
        printf("Block %s is not able to find its END\n" , );
    }
  }
  | TOK_BEGIN TOK_WRAP TOK_STRING blockcontents TOK_END TOK_STRING
;


blockcontents : item
      | blockcontents item
      ;


item    : TOK_NAME TOK_STRING        { cout << endl <<  << "->" <<  << "  "; }
| TOK_SIZE TOK_STRING        { cout <<  << "->" <<  << "  "; }
| TOK_ITERATE TOK_STRING     { cout <<  << "->" <<  << "  ";  }
| TOK_DIRECTION TOK_STRING   { cout << endl <<  << "->" <<  << "  " << endl; }
| TOK_STRAP TOK_STRING       { cout  <<  << "->" <<  << "  "; }
| TOK_WRAP TOK_STRING        { cout <<  << "->" <<  << "  "; }
| TOK_VIA TOK_STRING         { cout <<  << "->" <<  << "  " << endl; }
| TOK_VERSION TOK_STRING     {}
| TOK_UNIQUE TOK_STRING      { cout << endl <<  << "->" <<  << "  " << endl; }
| TOK_REF TOK_STRING         { cout << endl <<  << "->" <<  << "  " << endl; }
| TOK_POS TOK_STRING         { cout << endl <<  << "->" <<  << "  " << endl; }
| TOK_CON TOK_STRING         { cout << endl <<  << "->" <<  << "  " << endl; }
| TOK_ORI TOK_STRING         { cout << endl <<  << "->" <<  << "  " << endl; }  
| block
;




%%



int main(void) {
FILE * pt = fopen("LG.txt", "r" );
if(!pt)
{
cout << "Bad Input.Noexistant file" << endl;
return -1;
}
yyin = pt;
do
{
//yydebug = 1;
    yyparse();
}while (!feof(yyin));      
}
void yyerror(const char *s) {
    cout << "parse error on line " << line_num << "!  Message: " << s << endl;
    exit(-1);
}

extern "C" int yywrap()
{
        return (1 == 1);
}



#include "lex.yy.c"

Answer 1

你需要做什么它使用 -d 选项标志启用词法分析器的调试模式，并使用 -t 标志启用解析跟踪模式。您还必须向主程序添加几行以启用解析器跟踪：

将这些行添加到 ayacc.y 在 int main(void) { 之后：

    extern int yydebug;
    yydebug = 1;

现在使用调试和跟踪构建：

flex -d lex.l
bison -t -d ayacc.y

现在当你运行你得到这个：

Starting parse
Entering state 0
Reading a token: --(end of buffer or a NUL)
--accepting rule at line 80 ("BEGIN")
Next token is token TOK_BEGIN ()
Shifting token TOK_BEGIN ()
Entering state 1
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 71 ("WRAP")
Next token is token TOK_WRAP ()
Shifting token TOK_WRAP ()
Entering state 7
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 109 ("WIO3")
Next token is token TOK_STRING ()
Shifting token TOK_STRING ()
Entering state 29
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 119 ("
")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 56 ("NAME")
Next token is token TOK_NAME ()
Shifting token TOK_NAME ()
Entering state 12
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 109 ("lgCell_prg160_io")
Next token is token TOK_STRING ()
Shifting token TOK_STRING ()
Entering state 32
Reducing stack by rule 12 (line 109):
    = token TOK_NAME ()
    = token TOK_STRING ()

-> $$ = nterm item ()
Stack now 0 1 7 29
Entering state 27
Reducing stack by rule 10 (line 104):
    = nterm item ()
-> $$ = nterm blockcontents ()
Stack now 0 1 7 29
Entering state 48
Reading a token: --accepting rule at line 119 ("
")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 103 ("CONDITION")
Next token is token TOK_CON ()
Shifting token TOK_CON ()
Entering state 23
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 52 (" ")
--accepting rule at line 109 ("UNI_PLACE_GLOBAL")
Next token is token TOK_STRING ()
Shifting token TOK_STRING ()
Entering state 43
Reducing stack by rule 23 (line 120):
    = token TOK_CON ()
    = token TOK_STRING ()
NAME->lgCell_prg160_io  
CONDITION->UNI_PLACE_GLOBAL  
-> $$ = nterm item ()
Stack now 0 1 7 29 48
Entering state 46
Reducing stack by rule 11 (line 105):
    = nterm blockcontents ()
    = nterm item ()
-> $$ = nterm blockcontents ()
Stack now 0 1 7 29
Entering state 48
Reading a token: --accepting rule at line 52 (" ")
--accepting rule at line 109 ("&&")
Next token is token TOK_STRING ()
parse error on line 3!  Message: syntax error

您可以看到它使用词法分析器规则正确地忽略了空格。您的问题是 && 符号被识别为 TOK_STRING，这不是语法规则所期望的。

不知道你的语言的正确语法应该是什么（你没有说）没有更多信息我无法为你解决这个问题。您可能希望修复 TOK_STRING 规则以仅匹配字符串！

在 flex 和 bison 中忽略白色 space

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