有没有相互递归的例子? [英] Are there any example of Mutual recursion?

问题描述

是否有任何递归函数调用另一个调用第一个函数的递归函数的例子?

Are there any examples for a recursive function that calls an other function which calls the first one too ?

示例:

function1()
{    
    //do something 
    function2();
    //do something
}

function2()
{
    //do something 
    function1();
    //do something
}

推荐答案

相互递归在解析数学表达式(和其他语法)的代码中很常见.基于以下语法的递归下降解析器自然会包含相互递归:expression-terms-term-factor-primary-expression.

Mutual recursion is common in code that parses mathematical expressions (and other grammars). A recursive descent parser based on the grammar below will naturally contain mutual recursion: expression-terms-term-factor-primary-expression.

expression
    + terms
    - terms
    terms

terms
    term + terms
    term - terms

term
    factor
    factor * term
    factor / term

factor
    primary
    primary ^ factor

primary
    ( expression )
    number
    name
    name ( expression )

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