操作precedence在boost ::精神？ [英] Operator precedence in boost::spirit?

问题描述

我用做精神mini_c样品一些测试。遗憾的是它并没有保持运营precedence预期：

I made some tests using the spirit mini_c sample. Unfortunately it does not keep the operator precedence as expected:

int main()
{
    return 3 > 10 || 3 > 1;
}

计算结果为0。

return (3 > 10) || (3 > 1);

返回1

我试着动||的定义和与＆amp;＆放大器;在的构造函数

I tried to move the definition of "||" and "&&" to the very top in the constructor of

template <typename Iterator>
expression<Iterator>::expression(

但是，这并不能改变什么。那怎么可以修复。我使用的提振38年3月1日。

but that does not change anything. How can that be fixed. I am using boost 1.3.38.

推荐答案

确认，这是在与运营商precedence的mini_c例子中的错误。我犯了一个修复程序SVN，这将是加速V1.45可用。以下是我在头文件mini_cb.hpp改变：

Confirmed, that's a bug in the mini_c example related to operator precedence. I committed a fix to SVN, which will be available in Boost V1.45. Here is what I changed in the header file mini_cb.hpp:

老code：

equality_expr =
    relational_expr
    >> *(   ("==" > relational_expr     [op(op_eq)])
        |   ("!=" > relational_expr     [op(op_neq)])
        )
    ;

relational_expr =
    logical_expr
    >> *(   ("<=" > logical_expr        [op(op_lte)])
        |   ('<' > logical_expr         [op(op_lt)])
        |   (">=" > logical_expr        [op(op_gte)])
        |   ('>' > logical_expr         [op(op_gt)])
        )
    ;

logical_expr =
    additive_expr
    >> *(   ("&&" > additive_expr       [op(op_and)])
        |   ("||" > additive_expr       [op(op_or)])
        )
    ;

新的code：

equality_expr =
    logical_expr
    >> *(   ("==" > logical_expr        [op(op_eq)])
        |   ("!=" > logical_expr        [op(op_neq)])
        )
    ;

logical_expr =
    relational_expr
    >> *(   ("&&" > relational_expr     [op(op_and)])
        |   ("||" > relational_expr     [op(op_or)])
        )
    ;

relational_expr =
    additive_expr
    >> *(   ("<=" > additive_expr       [op(op_lte)])
        |   ('<' > additive_expr        [op(op_lt)])
        |   (">=" > additive_expr       [op(op_gte)])
        |   ('>' > additive_expr        [op(op_gt)])
        )
    ;

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