yacc-Flex中的移位/减少冲突

Question

我在yacc中有以下语法，但是我得到1个shift /减少冲突：

   %union {
   char* integer;
    char* string;
    char* boolean;
    char* date;
};



%token <integer> INTEGER
%token <string> STRING
%token <boolean> BOOLEAN
%token <date> DATE
%token WORKBOOK_START WORKBOOK_END STYLES_START STYLES_END STYLE_START STYLE_END WORKSHEET_START
%token WORKSHEET_END CLOSE_TAG EQUAL QUOTES COL_END_TAG
%token TABLE_START TABLE_END COLUMN_START ROW_START ROW_END CELL_START CELL_END DATA_START DATA_END
%token ID NAME PROTECTED EXPCOLCOUNT EXPROWCOUNT STYLEID HIDDEN WIDTH HEIGHT MERGEACR MERGEDOWN TYPE
%token MY_NUMBER MY_STRING MY_BOOL MY_DATETIME

%%
WORKBOOK: WORKBOOK_START INWORKBOOK WORKBOOK_END ;

INWORKBOOK: WORKSHEET MORE_WORKSHEETS 
      | NUM_STYLES WORKSHEET MORE_WORKSHEETS
      ;

MORE_WORKSHEETS: WORKSHEET MORE_WORKSHEETS
           |
           ;

NUM_STYLES: STYLES NUM_STYLES
      |
      ;

STYLES: STYLES_START INSTYLES STYLES_END ;

INSTYLES: STYLE INSTYLES
    |
    ;

STYLE: STYLE_START INSTYLE STYLE_END ;

INSTYLE: id CLOSE_TAG ; 

id: ID EQUAL QUOTES STRING QUOTES {checkID($4);};

WORKSHEET: WORKSHEET_START INWORKSHEET WORKSHEET_END  ;

INWORKSHEET: name protected CLOSE_TAG MORE_TABLES
       | protected name CLOSE_TAG MORE_TABLES
       | name CLOSE_TAG MORE_TABLES
       ;

name: NAME EQUAL QUOTES STRING QUOTES ;

%%

我使用了-v选项来生成所产生的冲突，看来我在WORKBOOK: WORKBOOK_START INWORKBOOK WORKBOOK_END ;中遇到了问题

State 1
1 WORKBOOK: WORKBOOK_START . INWORKBOOK WORKBOOK_END
STYLES_START     shift, and go to state 3
WORKSHEET_START  shift, and go to state 4
WORKSHEET_START  [reduce using rule 7 (NUM_STYLES)]
INWORKBOOK  go to state 5
NUM_STYLES  go to state 6
STYLES      go to state 7
WORKSHEET   go to state 8

如何解决此问题？有什么建议吗？

Answer 1

NUM_STYLES可以为空。因此，给出了两种选择：

INWORKBOOK: WORKSHEET MORE_WORKSHEETS 
          | NUM_STYLES WORKSHEET MORE_WORKSHEETS

如果输入的星标带有可能是WORKSHEET开头的令牌，则解析器无法告诉它是否应该使用第一个产生式，还是应该减少空的{{1} }，然后使用第二个产品。

您应该再次查看状态表，并尝试查看状态表如何告诉您该问题。