wip: provide/inject

packages/runtime-core/src/apiInject.ts

@@ -0,0 +1,30 @@
+import { value, isValue, Value } from './apiState'
+import { currentInstance } from './component'
+
+export interface Key<T> extends Symbol {}
+
+export function provide<T>(key: Key<T>, value: T | Value<T>) {
+  if (!currentInstance) {
+    // TODO warn
+  } else {
+    const provides = currentInstance.provides || (currentInstance.provides = {})
+    provides[key as any] = value
+  }
+}
+
+export function inject<T>(key: Key<T>): Value<T> | undefined {
+  // traverse parent chain and look for provided value
+  if (!currentInstance) {
+    // TODO warn
+  } else {
+    let parent = currentInstance.parent
+    while (parent) {
+      const { provides } = parent
+      if (provides !== null && provides.hasOwnProperty(key as any)) {
+        const val = provides[key as any]
+        return isValue(val) ? val : value(val)
+      }
+      parent = parent.parent
+    }
+  }
+}