我試圖建立一個與野牛解析器,並已將我的所有錯誤縮小到一個困難的。野牛:衝突:1移位/減少錯誤
下面是與國家野牛的調試輸出,其中的錯誤在於:
state 120
12 statement_list: statement_list . SEMICOLON statement
24 if_statement: IF conditional THEN statement_lists ELSE statement_list .
SEMICOLON shift, and go to state 50
SEMICOLON [reduce using rule 24 (if_statement)]
$default reduce using rule 24 (if_statement)
這裏是在parser.y源
%%
program : ID COLON block ENDP ID POINT
;
block : CODE statement_list
| DECLARATIONS declaration_block CODE statement_list
;
declaration_block : id_list OF TYPE type SEMICOLON
| declaration_block id_list OF TYPE type SEMICOLON
;
id_list : ID
| ID COMMA id_list
;
type : CHARACTER
| INTEGER
| REAL
;
statement_list : statement
| statement_list SEMICOLON statement
;
statement_lists : statement
| statement_list SEMICOLON statement
;
statement : assignment_statement
| if_statement
| do_statement
| while_statement
| for_statement
| write_statement
| read_statement
;
assignment_statement : expression OUTPUTTO ID
;
if_statement : IF conditional THEN statement_lists ENDIF
| IF conditional THEN statement_lists ELSE statement_list
;
do_statement : DO statement_list WHILE conditional ENDDO
;
while_statement : WHILE conditional DO statement_list ENDWHILE
;
for_statement : FOR ID IS expression BY expressions TO expression DO statement_list ENDFOR
;
write_statement : WRITE BRA output_list KET
| NEWLINE
;
read_statement : READ BRA ID KET
;
output_list : value
| value COMMA output_list
;
condition : expression comparator expression
;
conditional : condition
| NOT conditional
| condition AND conditional
| condition OR conditional
;
comparator : ASSIGNMENT
| BETWEEN
| LT
| GT
| LESSEQUAL
| GREATEREQUAL
;
expression : term
| term PLUS expression
| term MINUS expression
;
expressions : term
| term PLUS expressions
| term MINUS expressions
;
term : value
| value MULTIPLY term
| value DIVIDE term
;
value : ID
| constant
| BRA expression KET
;
constant : number_constant
| CHARCONST
;
number_constant : NUMBER
| MINUS NUMBER
| NUMBER POINT NUMBER
| MINUS NUMBER POINT NUMBER
;
%%
翻譯規則,當我刪除了if_statement規則有沒有錯誤,所以我已經將其縮小了很多,但仍然無法解決錯誤。
感謝您的任何幫助。
你的語法怎麼沒有結束,if-else與endif如同所有其他這樣的結構一樣? – Hobblin
另外,我不確定,但我想我已經解決類似的問題,指定一個特殊的「else_statement」,可以是「else語句」或空,並指定如果「如果statment else_statement」 – Hobblin
謝謝很多。不能相信我錯過了:) – Lee