feat(compiler): element codegen

packages/runtime-core/src/helpers/renderList.ts

@@ -0,0 +1,2 @@
+// TODO
+export function renderList() {}

packages/runtime-core/src/helpers/resolveAssets.ts

@@ -0,0 +1,34 @@
+import { currentRenderingInstance } from '../componentRenderUtils'
+import { currentInstance, Component } from '../component'
+import { Directive } from '../directives'
+import { camelize, capitalize } from '@vue/shared'
+import { warn } from '../warning'
+
+export function resolveComponent(name: string): Component | undefined {
+  return resolveAsset('components', name) as any
+}
+
+export function resolveDirective(name: string): Directive | undefined {
+  return resolveAsset('directives', name) as any
+}
+
+function resolveAsset(type: 'components' | 'directives', name: string) {
+  const instance = currentRenderingInstance || currentInstance
+  if (instance) {
+    let camelized
+    const registry = instance[type]
+    const res =
+      registry[name] ||
+      registry[(camelized = camelize(name))] ||
+      registry[capitalize(camelized)]
+    if (__DEV__ && !res) {
+      warn(`Failed to resolve ${type.slice(0, -1)}: ${name}`)
+    }
+    return res
+  } else if (__DEV__) {
+    warn(
+      `resolve${capitalize(type.slice(0, -1))} ` +
+        `can only be used in render() or setup().`
+    )
+  }
+}