c++-如何在flex中重新启动启动状态数据

我在flex中创建了一个开始条件（字符串），一切正常。然而，当我两次解析同一个字符串时，使用开始条件的元素消失了。我该怎么解决？请帮帮我flex文件

   
%option stack noyywrap
%{
extern int lineNumber; // definie dans prog.y, utilise par notre code pour \n
#include "h5parse.hpp"
#include 
#include 

using namespace std;
extern string initialdata;
extern string pdata;
extern bool loop;
string val;
string compile(string content);
string compilefile(string path);
void runwithargs(int argc ,char ** argv);
int saveoutput(string compileddata ,string outputpath="");

%}
%x strenv
i_command       @include
e_command       @extends
l_command       @layout
f_command       @field

command {i_command}|{e_command}|{l_command}|{f_command}

%%
"\""       { val.clear(); BEGIN(strenv); }
"\""    { BEGIN(INITIAL);sprintf(yylval.str,"%s",val.c_str());return(STRING); }
<> { BEGIN(INITIAL); sprintf(yylval.str,"%s",val.c_str());return(STRING); }
.       { val+=yytext[0]; }
{command}       {sprintf(yylval.str,"%s",yytext);return (COMMAND);}
"("             { return LPAREN; }
")"             { return RPAREN; }
"{"             { return LBRACE; }
"}"             { return RBRACE; }
.|\n            {yylval.c=yytext[0];return TXT; }
%%

//our main function 
int main(int argc,char ** argv)
{

if(argc>1)runwithargs(argc,argv);// if there are arguments run with them

system("pause");//don't quit the app at the end of assembly
return(0);
}

//run h5A by using  arguments
void runwithargs(int argc ,char ** argv)
{
    if(argc == 2)
        saveoutput(compilefile(argv[1]));
    
}

//assemble a string 
string compile(string content)
{

do 
{
loop=false;
pdata.clear();
 YY_BUFFER_STATE b =yy_scan_string(content.c_str());

yyparse();
content=pdata; 

 }while(loop==true);
return content;
}

//assemble file
string compilefile(string path)
{
string data;
ifstream inputfile(path,ios::in|ios::binary|ios::ate);
int length  = inputfile.tellg();           
inputfile.seekg(0, std::ios::beg);  
char * buffer = new char[length];// allocate memory for a buffer of appropriate dimension
inputfile.read(buffer, length);// read the whole file into the buffer
inputfile.close();  
cout<<"start assembly : "<<path<<endl;
return compile(string(buffer));
}

//save  assembled  file to a specified path 
int saveoutput(string compileddata ,string outputpath)
{

outputpath=(outputpath=="")?"output":outputpath;
ofstream outputfile  ("output");
//dhow the compiled data in console if we're in debug 
outputfile<<compileddata;
cout<<compileddata<<endl;
cout<<"operation terminated successfuly , output at :"
    <<outputpath<<endl;

return 0;

}

bison file

%{
#include 
#include 
#include
#include