bison - 这个 Bison 代码中的 shift/reduce 冲突来自哪里？

Question

我正在尝试解析此语法:

34 + 1 − 8, 32 * 87 + 6 / 4, 34 / 8

我希望像这样接地:

(, (- (+ 34 1) 8) (/ (+ (* 32 87) 6) 4) (/ 34 8))

这是 BISON 的代码:

%token NUMBER
%token COMMA
%token OPERATOR
%left OPERATOR
%left COMMA
%%

term: NUMBER | term op term ;
op: OPERATOR | COMMA;
%%

有一个问题:

test.y: conflicts: 2 shift/reduce

我该如何解决？

Answer 1

要查找冲突的位置，请使用 --verbose选项并查看文件 example.output您的输入文件在哪里 example.y .这是我从您的输入中获得的文件:

State 7 conflicts: 2 shift/reduce

(略)

state 7

    2 term: term . op term
    2     | term op term .

    COMMA     shift, and go to state 4
    OPERATOR  shift, and go to state 5

    COMMA     [reduce using rule 2 (term)]
    OPERATOR  [reduce using rule 2 (term)]
    $default  reduce using rule 2 (term)

    op  go to state 6