99 lines
2.8 KiB
TypeScript
99 lines
2.8 KiB
TypeScript
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import {
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RootNode,
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NodeTypes,
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TemplateChildNode,
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CallExpression,
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ElementNode
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} from '../ast'
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import { TransformContext } from '../transform'
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import { CREATE_VNODE } from '../runtimeConstants'
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import { PropsExpression } from './transformElement'
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export function hoistStaticTrees(root: RootNode, context: TransformContext) {
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walk(root.children, context, new Set<TemplateChildNode>())
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}
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function walk(
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children: TemplateChildNode[],
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context: TransformContext,
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knownStaticNodes: Set<TemplateChildNode>
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) {
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for (let i = 0; i < children.length; i++) {
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const child = children[i]
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if (child.type === NodeTypes.ELEMENT) {
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if (isStaticNode(child, knownStaticNodes)) {
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// whole tree is static
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child.codegenNode = context.hoist(child.codegenNode!)
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continue
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} else if (!getPatchFlag(child)) {
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// has dynamic children, but self props are static, hoist props instead
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const props = (child.codegenNode as CallExpression).arguments[1] as
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| PropsExpression
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| `null`
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if (props !== `null`) {
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;(child.codegenNode as CallExpression).arguments[1] = context.hoist(
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props
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)
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}
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}
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}
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if (child.type === NodeTypes.ELEMENT || child.type === NodeTypes.FOR) {
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walk(child.children, context, knownStaticNodes)
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} else if (child.type === NodeTypes.IF) {
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for (let i = 0; i < child.branches.length; i++) {
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walk(child.branches[i].children, context, knownStaticNodes)
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}
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}
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}
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}
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function getPatchFlag(node: ElementNode): number | undefined {
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const codegenNode = node.codegenNode as CallExpression
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if (
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// callee is createVNode (i.e. no runtime directives)
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codegenNode.callee.includes(CREATE_VNODE)
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) {
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const flag = codegenNode.arguments[3]
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return flag ? parseInt(flag as string, 10) : undefined
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}
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}
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function isStaticNode(
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node: TemplateChildNode,
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knownStaticNodes: Set<TemplateChildNode>
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): boolean {
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switch (node.type) {
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case NodeTypes.ELEMENT:
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if (knownStaticNodes.has(node)) {
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return true
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}
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const flag = getPatchFlag(node)
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if (!flag) {
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// element self is static. check its children.
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for (let i = 0; i < node.children.length; i++) {
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if (!isStaticNode(node.children[i], knownStaticNodes)) {
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return false
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}
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}
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knownStaticNodes.add(node)
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return true
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} else {
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return false
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}
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case NodeTypes.TEXT:
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case NodeTypes.COMMENT:
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return true
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case NodeTypes.IF:
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case NodeTypes.FOR:
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case NodeTypes.INTERPOLATION:
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case NodeTypes.COMPOUND_EXPRESSION:
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return false
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default:
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if (__DEV__) {
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const exhaustiveCheck: never = node
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exhaustiveCheck
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}
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return false
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}
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}
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