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node_modules/vue-router/src/composables/guards.js

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+import { getCurrentInstance, onUnmounted } from 'vue'
+import { throwNoCurrentInstance } from './utils'
+import { useRouter } from './globals'
+
+export function onBeforeRouteUpdate (guard) {
+  if (process.env.NODE_ENV !== 'production') {
+    throwNoCurrentInstance('onBeforeRouteUpdate')
+  }
+
+  return useFilteredGuard(guard, isUpdateNavigation)
+}
+function isUpdateNavigation (to, from, depth) {
+  const toMatched = to.matched
+  const fromMatched = from.matched
+  return (
+    toMatched.length >= depth &&
+    toMatched
+      .slice(0, depth + 1)
+      .every((record, i) => record === fromMatched[i])
+  )
+}
+
+function isLeaveNavigation (to, from, depth) {
+  const toMatched = to.matched
+  const fromMatched = from.matched
+  return toMatched.length < depth || toMatched[depth] !== fromMatched[depth]
+}
+
+export function onBeforeRouteLeave (guard) {
+  if (process.env.NODE_ENV !== 'production') {
+    throwNoCurrentInstance('onBeforeRouteLeave')
+  }
+
+  return useFilteredGuard(guard, isLeaveNavigation)
+}
+
+const noop = () => {}
+function useFilteredGuard (guard, fn) {
+  const instance = getCurrentInstance()
+  const router = useRouter()
+
+  let target = instance.proxy
+  // find the nearest RouterView to know the depth
+  while (
+    target &&
+    target.$vnode &&
+    target.$vnode.data &&
+    target.$vnode.data.routerViewDepth == null
+  ) {
+    target = target.$parent
+  }
+
+  const depth =
+    target && target.$vnode && target.$vnode.data
+      ? target.$vnode.data.routerViewDepth
+      : null
+
+  if (depth != null) {
+    const removeGuard = router.beforeEach((to, from, next) => {
+      return fn(to, from, depth) ? guard(to, from, next) : next()
+    })
+
+    onUnmounted(removeGuard)
+    return removeGuard
+  }
+
+  return noop
+}