295 lines
8.6 KiB
TypeScript
295 lines
8.6 KiB
TypeScript
/**
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* This module is Node-only.
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*/
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import {
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NodeTypes,
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ElementNode,
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TransformContext,
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TemplateChildNode,
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SimpleExpressionNode,
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createCallExpression,
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HoistTransform,
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CREATE_STATIC,
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ExpressionNode,
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ElementTypes,
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PlainElementNode,
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JSChildNode
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} from '@vue/compiler-core'
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import {
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isVoidTag,
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isString,
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isSymbol,
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isKnownAttr,
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escapeHtml,
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toDisplayString,
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normalizeClass,
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normalizeStyle,
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stringifyStyle
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} from '@vue/shared'
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export const enum StringifyThresholds {
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ELEMENT_WITH_BINDING_COUNT = 5,
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NODE_COUNT = 20
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}
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// Turn eligible hoisted static trees into stringied static nodes, e.g.
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// const _hoisted_1 = createStaticVNode(`<div class="foo">bar</div>`)
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// This is only performed in non-in-browser compilations.
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export const stringifyStatic: HoistTransform = (children, context) => {
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let nc = 0 // current node count
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let ec = 0 // current element with binding count
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const currentChunk: PlainElementNode[] = []
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const stringifyCurrentChunk = (currentIndex: number): number => {
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if (
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nc >= StringifyThresholds.NODE_COUNT ||
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ec >= StringifyThresholds.ELEMENT_WITH_BINDING_COUNT
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) {
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// combine all currently eligible nodes into a single static vnode call
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const staticCall = createCallExpression(context.helper(CREATE_STATIC), [
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JSON.stringify(
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currentChunk.map(node => stringifyElement(node, context)).join('')
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),
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// the 2nd argument indicates the number of DOM nodes this static vnode
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// will insert / hydrate
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String(currentChunk.length)
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])
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// replace the first node's hoisted expression with the static vnode call
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replaceHoist(currentChunk[0], staticCall, context)
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if (currentChunk.length > 1) {
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for (let i = 1; i < currentChunk.length; i++) {
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// for the merged nodes, set their hoisted expression to null
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replaceHoist(currentChunk[i], null, context)
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}
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// also remove merged nodes from children
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const deleteCount = currentChunk.length - 1
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children.splice(currentIndex - currentChunk.length + 1, deleteCount)
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return deleteCount
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}
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}
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return 0
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}
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let i = 0
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for (; i < children.length; i++) {
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const child = children[i]
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const hoisted = getHoistedNode(child)
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if (hoisted) {
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// presence of hoisted means child must be a plain element Node
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const node = child as PlainElementNode
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const result = analyzeNode(node)
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if (result) {
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// node is stringifiable, record state
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nc += result[0]
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ec += result[1]
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currentChunk.push(node)
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continue
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}
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}
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// we only reach here if we ran into a node that is not stringifiable
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// check if currently analyzed nodes meet criteria for stringification.
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// adjust iteration index
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i -= stringifyCurrentChunk(i)
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// reset state
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nc = 0
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ec = 0
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currentChunk.length = 0
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}
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// in case the last node was also stringifiable
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stringifyCurrentChunk(i)
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}
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const getHoistedNode = (node: TemplateChildNode) =>
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node.type === NodeTypes.ELEMENT &&
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node.tagType === ElementTypes.ELEMENT &&
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node.codegenNode &&
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node.codegenNode.type === NodeTypes.SIMPLE_EXPRESSION &&
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node.codegenNode.hoisted
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const dataAriaRE = /^(data|aria)-/
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const isStringifiableAttr = (name: string) => {
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return isKnownAttr(name) || dataAriaRE.test(name)
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}
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const replaceHoist = (
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node: PlainElementNode,
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replacement: JSChildNode | null,
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context: TransformContext
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) => {
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const hoistToReplace = (node.codegenNode as SimpleExpressionNode).hoisted!
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context.hoists[context.hoists.indexOf(hoistToReplace)] = replacement
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}
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/**
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* for a hoisted node, analyze it and return:
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* - false: bailed (contains runtime constant)
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* - [x, y] where
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* - x is the number of nodes inside
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* - y is the number of element with bindings inside
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*/
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function analyzeNode(node: PlainElementNode): [number, number] | false {
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let nc = 1 // node count
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let ec = node.props.length > 0 ? 1 : 0 // element w/ binding count
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let bailed = false
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const bail = (): false => {
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bailed = true
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return false
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}
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// TODO: check for cases where using innerHTML will result in different
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// output compared to imperative node insertions.
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// probably only need to check for most common case
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// i.e. non-phrasing-content tags inside `<p>`
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function walk(node: ElementNode): boolean {
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for (let i = 0; i < node.props.length; i++) {
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const p = node.props[i]
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// bail on non-attr bindings
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if (p.type === NodeTypes.ATTRIBUTE && !isStringifiableAttr(p.name)) {
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return bail()
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}
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if (p.type === NodeTypes.DIRECTIVE && p.name === 'bind') {
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// bail on non-attr bindings
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if (
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p.arg &&
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(p.arg.type === NodeTypes.COMPOUND_EXPRESSION ||
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(p.arg.isStatic && !isStringifiableAttr(p.arg.content)))
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) {
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return bail()
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}
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// some transforms, e.g. `transformAssetUrls` in `@vue/compiler-sfc` may
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// convert static attributes into a v-bind with a constnat expresion.
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// Such constant bindings are eligible for hoisting but not for static
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// stringification because they cannot be pre-evaluated.
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if (
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p.exp &&
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(p.exp.type === NodeTypes.COMPOUND_EXPRESSION ||
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p.exp.isRuntimeConstant)
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) {
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return bail()
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}
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}
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}
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for (let i = 0; i < node.children.length; i++) {
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nc++
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if (nc >= StringifyThresholds.NODE_COUNT) {
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return true
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}
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const child = node.children[i]
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if (child.type === NodeTypes.ELEMENT) {
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if (child.props.length > 0) {
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ec++
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if (ec >= StringifyThresholds.ELEMENT_WITH_BINDING_COUNT) {
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return true
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}
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}
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walk(child)
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if (bailed) {
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return false
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}
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}
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}
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return true
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}
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return walk(node) ? [nc, ec] : false
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}
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function stringifyElement(
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node: ElementNode,
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context: TransformContext
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): string {
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let res = `<${node.tag}`
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for (let i = 0; i < node.props.length; i++) {
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const p = node.props[i]
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if (p.type === NodeTypes.ATTRIBUTE) {
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res += ` ${p.name}`
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if (p.value) {
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res += `="${escapeHtml(p.value.content)}"`
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}
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} else if (p.type === NodeTypes.DIRECTIVE && p.name === 'bind') {
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// constant v-bind, e.g. :foo="1"
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let evaluated = evaluateConstant(p.exp as SimpleExpressionNode)
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const arg = p.arg && (p.arg as SimpleExpressionNode).content
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if (arg === 'class') {
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evaluated = normalizeClass(evaluated)
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} else if (arg === 'style') {
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evaluated = stringifyStyle(normalizeStyle(evaluated))
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}
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res += ` ${(p.arg as SimpleExpressionNode).content}="${escapeHtml(
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evaluated
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)}"`
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}
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}
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if (context.scopeId) {
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res += ` ${context.scopeId}`
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}
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res += `>`
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for (let i = 0; i < node.children.length; i++) {
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res += stringifyNode(node.children[i], context)
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}
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if (!isVoidTag(node.tag)) {
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res += `</${node.tag}>`
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}
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return res
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}
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function stringifyNode(
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node: string | TemplateChildNode,
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context: TransformContext
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): string {
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if (isString(node)) {
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return node
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}
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if (isSymbol(node)) {
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return ``
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}
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switch (node.type) {
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case NodeTypes.ELEMENT:
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return stringifyElement(node, context)
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case NodeTypes.TEXT:
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return escapeHtml(node.content)
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case NodeTypes.COMMENT:
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return `<!--${escapeHtml(node.content)}-->`
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case NodeTypes.INTERPOLATION:
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return escapeHtml(toDisplayString(evaluateConstant(node.content)))
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case NodeTypes.COMPOUND_EXPRESSION:
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return escapeHtml(evaluateConstant(node))
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case NodeTypes.TEXT_CALL:
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return stringifyNode(node.content, context)
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default:
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// static trees will not contain if/for nodes
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return ''
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}
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}
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// __UNSAFE__
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// Reason: eval.
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// It's technically safe to eval because only constant expressions are possible
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// here, e.g. `{{ 1 }}` or `{{ 'foo' }}`
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// in addition, constant exps bail on presence of parens so you can't even
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// run JSFuck in here. But we mark it unsafe for security review purposes.
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// (see compiler-core/src/transformExpressions)
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function evaluateConstant(exp: ExpressionNode): string {
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if (exp.type === NodeTypes.SIMPLE_EXPRESSION) {
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return new Function(`return ${exp.content}`)()
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} else {
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// compound
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let res = ``
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exp.children.forEach(c => {
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if (isString(c) || isSymbol(c)) {
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return
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}
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if (c.type === NodeTypes.TEXT) {
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res += c.content
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} else if (c.type === NodeTypes.INTERPOLATION) {
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res += toDisplayString(evaluateConstant(c.content))
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} else {
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res += evaluateConstant(c)
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}
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})
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return res
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}
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}
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