VueRouter 构造函数中的 this.matcher

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export default class VueRouter {
  static install: () => void;
  static version: string;

  app: any; // Vue 实例
  apps: Array<any>;
  ready: boolean;
  readyCbs: Array<Function>;
  options: RouterOptions;
  mode: string; // 路由使用的模式
  history: HashHistory | HTML5History | AbstractHistory;
  matcher: Matcher;
  fallback: boolean;
  beforeHooks: Array<?NavigationGuard>;
  resolveHooks: Array<?NavigationGuard>;
  afterHooks: Array<?AfterNavigationHook>;

  constructor (options: RouterOptions = {}) {
    // code...
    // 生成路由匹配
    this.matcher = createMatcher(options.routes || [], this)

    // code...
  }

构造函数中的 this.matcher = createMatcher(options.routes || [], this) 会根据用户传入的路由信息构造出路由匹配，VueRouter 的路由对象就是由它内部生成的。

createMatcher

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export function createMatcher (
  routes: Array<RouteConfig>, // 配置的路由信息
  router: VueRouter // Vue-Router 实例
): Matcher {
  // 创建 route map，然后返回 pathList, pathMap, nameMap 供下次 addRoutes 使用
  const { pathList, pathMap, nameMap } = createRouteMap(routes)

  // 添加路由
  function addRoutes (routes) {
    createRouteMap(routes, pathList, pathMap, nameMap)
  }

  // 返回对应路由信息
  function match (
    raw: RawLocation,
    currentRoute?: Route,
    redirectedFrom?: Location
  ): Route {
    const location = normalizeLocation(raw, currentRoute, false, router)
    const { name } = location

    if (name) {
      const record = nameMap[name]
      if (process.env.NODE_ENV !== 'production') {
        warn(record, `Route with name '${name}' does not exist`)
      }
      if (!record) return _createRoute(null, location)
      const paramNames = record.regex.keys
        .filter(key => !key.optional)
        .map(key => key.name)

      if (typeof location.params !== 'object') {
        location.params = {}
      }

      if (currentRoute && typeof currentRoute.params === 'object') {
        for (const key in currentRoute.params) {
          if (!(key in location.params) && paramNames.indexOf(key) > -1) {
            location.params[key] = currentRoute.params[key]
          }
        }
      }

      location.path = fillParams(record.path, location.params, `named route "${name}"`)
      return _createRoute(record, location, redirectedFrom)
    } else if (location.path) {
      location.params = {}
      for (let i = 0; i < pathList.length; i++) {
        const path = pathList[i]
        const record = pathMap[path]
        if (matchRoute(record.regex, location.path, location.params)) {
          return _createRoute(record, location, redirectedFrom)
        }
      }
    }
    // no match
    return _createRoute(null, location)
  }

  function redirect (
    record: RouteRecord,
    location: Location
  ): Route {
    const originalRedirect = record.redirect
    let redirect = typeof originalRedirect === 'function'
      ? originalRedirect(createRoute(record, location, null, router))
      : originalRedirect

    if (typeof redirect === 'string') {
      redirect = { path: redirect }
    }

    if (!redirect || typeof redirect !== 'object') {
      if (process.env.NODE_ENV !== 'production') {
        warn(
          false, `invalid redirect option: ${JSON.stringify(redirect)}`
        )
      }
      return _createRoute(null, location)
    }

    const re: Object = redirect
    const { name, path } = re
    let { query, hash, params } = location
    query = re.hasOwnProperty('query') ? re.query : query
    hash = re.hasOwnProperty('hash') ? re.hash : hash
    params = re.hasOwnProperty('params') ? re.params : params

    if (name) {
      // resolved named direct
      const targetRecord = nameMap[name]
      if (process.env.NODE_ENV !== 'production') {
        assert(targetRecord, `redirect failed: named route "${name}" not found.`)
      }
      return match({
        _normalized: true,
        name,
        query,
        hash,
        params
      }, undefined, location)
    } else if (path) {
      // 1. resolve relative redirect
      const rawPath = resolveRecordPath(path, record)
      // 2. resolve params
      const resolvedPath = fillParams(rawPath, params, `redirect route with path "${rawPath}"`)
      // 3. rematch with existing query and hash
      return match({
        _normalized: true,
        path: resolvedPath,
        query,
        hash
      }, undefined, location)
    } else {
      if (process.env.NODE_ENV !== 'production') {
        warn(false, `invalid redirect option: ${JSON.stringify(redirect)}`)
      }
      return _createRoute(null, location)
    }
  }

  function alias (
    record: RouteRecord,
    location: Location,
    matchAs: string
  ): Route {
    const aliasedPath = fillParams(matchAs, location.params, `aliased route with path "${matchAs}"`)
    const aliasedMatch = match({
      _normalized: true,
      path: aliasedPath
    })
    if (aliasedMatch) {
      const matched = aliasedMatch.matched
      const aliasedRecord = matched[matched.length - 1]
      location.params = aliasedMatch.params
      return _createRoute(aliasedRecord, location)
    }
    return _createRoute(null, location)
  }

  function _createRoute (
    record: ?RouteRecord,
    location: Location,
    redirectedFrom?: Location
  ): Route {
    if (record && record.redirect) {
      return redirect(record, redirectedFrom || location)
    }
    if (record && record.matchAs) {
      return alias(record, location, record.matchAs)
    }
    return createRoute(record, location, redirectedFrom, router)
  }

  return {
    match,
    addRoutes
  }
}

createMatcher() 返回两个方法。match 用来返回匹配到的路由信息。addRoutes 用于动态添加路由。
createMatcher() 第一次被调用的时候就会调用 createRouteMap，用来初始化初始路由，返回 pathList, pathMap, nameMap。
当动态添加路由时仍调用 createRouteMap 方法，并以之前调用该方法的返回值为参数传入。

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// 创建 route map，然后返回 pathList, pathMap, nameMap 供下次 addRoutes 使用
const { pathList, pathMap, nameMap } = createRouteMap(routes)

// 添加路由
function addRoutes (routes) {
  // 传入之前调用 createRouteMap 的返回值
  createRouteMap(routes, pathList, pathMap, nameMap)
}

createRouteMap

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// 创建 route map
export function createRouteMap (
  routes: Array<RouteConfig>,
  oldPathList?: Array<string>,
  oldPathMap?: Dictionary<RouteRecord>,
  oldNameMap?: Dictionary<RouteRecord>
): {
  pathList: Array<string>,
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>
} {
  // 路径列表用于控制路径匹配优先级
  const pathList: Array<string> = oldPathList || []
  // $flow-disable-line
  const pathMap: Dictionary<RouteRecord> = oldPathMap || Object.create(null)
  // $flow-disable-line
  const nameMap: Dictionary<RouteRecord> = oldNameMap || Object.create(null)

  // 遍历所有传入的 routes 数据，调用 addRouteRecord 添加路由记录
  routes.forEach(route => {
    addRouteRecord(pathList, pathMap, nameMap, route)
  })

  // 确保通配符(*)路由始终在最后
  for (let i = 0, l = pathList.length; i < l; i++) {
    if (pathList[i] === '*') {
      pathList.push(pathList.splice(i, 1)[0])
      l--
      i--
    }
  }

  return {
    pathList,
    pathMap,
    nameMap
  }
}

createRouteMap 中遍历所有传入的 routes 数据，调用 addRouteRecord 添加路由记录。

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// 添加路由记录
function addRouteRecord (
  pathList: Array<string>,
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>,
  route: RouteConfig,
  parent?: RouteRecord,
  matchAs?: string
) {
  const { path, name } = route

  // code...

  const pathToRegexpOptions: PathToRegexpOptions =
    route.pathToRegexpOptions || {}
  const normalizedPath = normalizePath(path, parent, pathToRegexpOptions.strict)

  if (typeof route.caseSensitive === 'boolean') {
    pathToRegexpOptions.sensitive = route.caseSensitive
  }

  // 构造一个路由记录
  const record: RouteRecord = {
    path: normalizedPath,
    regex: compileRouteRegex(normalizedPath, pathToRegexpOptions),
    components: route.components || { default: route.component },
    instances: {},
    name,
    parent,
    matchAs,
    redirect: route.redirect,
    beforeEnter: route.beforeEnter,
    meta: route.meta || {},
    props:
      route.props == null
        ? {}
        : route.components
          ? route.props
          : { default: route.props }
  }

  // 处理子路由
  if (route.children) {
    // code...
  }

  if (!pathMap[record.path]) {
    pathList.push(record.path)
    pathMap[record.path] = record
  }

  // 处理路由别名
  if (route.alias !== undefined) {
    // code...
  }

  if (name) {
    if (!nameMap[name]) {
      nameMap[name] = record
    } else if (process.env.NODE_ENV !== 'production' && !matchAs) {
      warn(
        false,
        `Duplicate named routes definition: ` +
          `{ name: "${name}", path: "${record.path}" }`
      )
    }
  }
}

addRouteRecord 方法内首先会构造一个路由记录 record，如果存在子路由则递归调用 addRouteRecord。最后做对应处理后分别放入 addRouteRecord 的入参 pathMap 与 nameMap 中，由于引用传递就直接修改了外部的 pathMap 与 nameMap。

End