MyTinySTL 简单分析(一)--iterator.h

本文详细分析了MyTinySTL中的vector部分,重点讲解了iterator.h文件,包括type_traits中的元编程技巧、迭代器的五个关联类型、iterator_traits的作用以及如何通过has_iterator_cat判断迭代器类型。

MyTinySTL 简单分析

目前在学习STL,看到一个开源的项目MyTinySTL,非常不错。想着照着这个代码自己敲一遍应该也能有些进步。然后就开始了学习过程。

首先分析的是vector

以下是由vector.h关联的所有头文件

其中有几个文件是重复的,例如type_traits.h 等

下面是一一分析每个文件。

  1. type_traits.h

这个文件比较简单,主要定义了两个结构体

m_true_type
m_false_type

这两个都从下面这个结构体继承而来,

struct m_integral_constant
{
   static constexpr T value = v;
};

所以都有一个value值,分别是true,false;

然后还定义了is_pair

2. iterator.h

这个文件是迭代器

下面两个链接讲的比较清楚

Uncaught (in promise) RangeError: Maximum call stack size exceeded at String.replace (<anonymous>) at encode (vue-router.esm.js:45:6) at eval (vue-router.esm.js:140:16) at Array.map (<anonymous>) at stringifyQuery (vue-router.esm.js:114:8) at getFullPath (vue-router.esm.js:218:26) at createRoute (vue-router.esm.js:172:15) at _createRoute (vue-router.esm.js:1730:12) at Object.match (vue-router.esm.js:1632:12) at VueRouter.match (vue-router.esm.js:2948:23) encode @ vue-router.esm.js:45 eval @ vue-router.esm.js:140 stringifyQuery @ vue-router.esm.js:114 getFullPath @ vue-router.esm.js:218 createRoute @ vue-router.esm.js:172 _createRoute @ vue-router.esm.js:1730 match @ vue-router.esm.js:1632 match @ vue-router.esm.js:2948 transitionTo @ vue-router.esm.js:2259 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095 runQueue @ vue-router.esm.js:2103 confirmTransition @ vue-router.esm.js:2400 transitionTo @ vue-router.esm.js:2268 replace @ vue-router.esm.js:2739 eval @ vue-router.esm.js:2386 eval @ permissions.js:64 iterator @ vue-router.esm.js:2370 step @ vue-router.esm.js:2095了解此错误
07-12
### 路由配置导致 Maximum call stack size exceeded 错误的解决方法 在 Vue Router 中,`Maximum call stack size exceeded` 错误通常发生在路由导航逻辑中出现死循环的情况下。例如,在 `beforeEach` 钩子中频繁调用 `next()` 或错误地重定向到自身路径,会导致堆栈溢出并触发该错误。 #### 1. 死循环导致的 Maximum call stack size exceeded 错误 当使用 `router.beforeEach` 进行导航守卫时,如果逻辑处理不当,可能会造成无限循环。例如,在未正确判断目标路径的情况下,连续调用 `next('/login')` 会导致路由不断重定向,从而进入死循环[^3]。以下是可能导致错误的代码示例: ```javascript router.beforeEach((to, from, next) => { if (localStorage.getItem('userInfo')) { if (to.path === '/login') { next({ path: '/' }); } else { next(); } } else { next('/login'); // 如果 /login 页面没有正确处理,则可能进入死循环 } }); ``` 为了避免此问题,应确保在重定向时明确判断当前路径,并避免重复跳转到相同的路径。改进后的代码如下: ```javascript router.beforeEach((to, from, next) => { if (localStorage.getItem('userInfo')) { if (to.path === '/login') { next({ path: '/' }); } else { next(); } } else { if (to.path === '/login') { next(); // 如果已经在登录页,直接放行 } else { next('/login'); // 否则跳转到登录页 } } }); ``` #### 2. 路由重定向配置错误引发的死循环 在某些情况下,路由配置中的 `redirect` 属性也可能导致死循环。例如,当个路由的 `redirect` 指向自身路径时,Vue Router 会不断尝试匹配和重定向,最终导致堆栈溢出。以下是个典型的错误配置: ```javascript const routes = [ { path: '/index', component: Home, redirect: '/index', // 错误:重定向指向自身路径 children: [...] } ]; ``` 为了解决这个问题,应删除或修改此类重定向配置,确保每次 `redirect` 都能跳转到个有效的路径。正确的做法是将其指向其他页面或移除不必要的重定向: ```javascript const routes = [ { path: '/index', component: Home, // redirect: '/index', // 删除这行以避免死循环 children: [...] } ]; ``` #### 3. 使用 addRoutes 动态添加路由时的潜在问题 当使用 `addRoutes` 方法动态添加路由时,如果新增的路由仍然包含指向自身的 `redirect`,同样会导致死循环。例如,在刷新页面后重新从本地存储加载菜单数据时,若生成的路由配置中仍保留了对 `/index` 的重定向,就会导致堆栈溢出[^4]。解决方案是确保动态添加的路由中不包含无效的重定向规则: ```javascript if (menuData) { store.commit('ADD_MENU', menuData); const routes = mUtils.generateRoutesFromMenu(menuData); const asyncRouterMap = [ { path: '/index', name: '', hidden: true, component: require('./pages/home.vue').default, // redirect: '/index', // 禁止重定向到自身 children: routes } ]; router.addRoutes(asyncRouterMap); } ``` --- ###
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