Question

我今天有一个我的flex / bison脚本的问题。它不会检测多行注释。

%x COMMENT_MULTI
#\[                     yy_push_state(COMMENT_MULTI);

<COMMENT_MULTI>"]#"     yy_pop_state();
<COMMENT_MULTI>"\n"     {
                            yylloc->lines(yyleng);
                            yylloc->step();
                        }
<COMMENT_MULTI>.?

你能帮帮我吗？

Answer 1

这是我最终在C ++注释和块注释的bison定义中使用的解决方案：

%x COMMENT

"//".*\n                            ;                                                                                                                                                                 

"/*"                                BEGIN(COMMENT);                                                                                                                                                   
<COMMENT>"/*"                       printf("%s%d\n", "Warning: multiple comments opened at line: ", yylineno);                                                                                        
<COMMENT>"*/"                       BEGIN(INITIAL);                                                                                                                                                   
<COMMENT>"EOF"                      yyerror("Reached end of file while scanning comment");                                                                                                            
<COMMENT>.|"\n"                     ;

Answer 2

/*DECLARING A SPECIFIC STATE FOR THE BLOCK COMMENT*/
%x BLOCK_COMMENT 
%%

\/\* { // BEGINING OF A BLOCK COMMENT: ENTERS INTO 'BLOCK_COMMENT' STATE
    BEGIN(BLOCK_COMMENT);
    blockcomment_line_start = line;
    blockcomment_col_start = frcol;
    strncat(block_comment, yytext, sizeof(block_comment));
    }
<BLOCK_COMMENT>\*\/    {   // END OF BLOCK COMMENT
    if(strlen(block_comment)+strlen(yytext) >= BLOCK_COMMENT_BUFFER-10){ //ADDS "(...)" AT THE END OF THE STRING IN CASE IT HAS BEEN TRUNCATED
        block_comment[1013] = '\0';
        strcat(block_comment," (...) ");
    }
    strncat(block_comment, yytext, sizeof(block_comment));
    printf("@(%.3d,%.3d)\tBLOCK COMMENT\t- %s\n", blockcomment_line_start, blockcomment_col_start, block_comment);

    BEGIN(INITIAL); //COMES BACK TO THE INITIAL STATE
    }
<BLOCK_COMMENT>\n {
    line++; // STILL HAS TO INCREMENT THE LINE NUMBER WHEN THERE'S A LINE BREAK INSIDE THE COMMENT
    //strcat(block_comment, "\\n");
    strncat(block_comment, "\\n", sizeof(block_comment));
}   
<BLOCK_COMMENT>. { // IGNORE ALL OTHER CHARACTERS WHILE IN 'BLOCK_COMMENT' STATE 
    //strcat(block_comment, yytext);
    strncat(block_comment, yytext, sizeof(block_comment));
}   
<BLOCK_COMMENT><<EOF>> {    
    printf("ERROR! THE BLOCK COMMENT OPENED IN  @(%d,%d) HASN'T BEEN CLOSED! \t\n", blockcomment_line_start, blockcomment_col_start);
    return;
}

使用flex / bison进行多行注释声明

2 个答案: