vue3-core/packages/compiler-ssr/src/ssrCodegenTransform.ts

425 lines
12 KiB
TypeScript

import {
type BlockStatement,
type CallExpression,
type CompilerError,
type CompilerOptions,
ElementTypes,
type IfStatement,
type JSChildNode,
NodeTypes,
type PlainElementNode,
type RootNode,
type TemplateChildNode,
type TemplateLiteral,
createBlockStatement,
createCallExpression,
createCompoundExpression,
createRoot,
createSimpleExpression,
createTemplateLiteral,
createTransformContext,
isText,
processExpression,
} from '@vue/compiler-dom'
import {
DYNAMIC_END_ANCHOR_LABEL,
DYNAMIC_START_ANCHOR_LABEL,
escapeHtml,
isString,
} from '@vue/shared'
import { SSR_INTERPOLATE, ssrHelpers } from './runtimeHelpers'
import { ssrProcessIf } from './transforms/ssrVIf'
import { ssrProcessFor } from './transforms/ssrVFor'
import { ssrProcessSlotOutlet } from './transforms/ssrTransformSlotOutlet'
import { ssrProcessComponent } from './transforms/ssrTransformComponent'
import { ssrProcessElement } from './transforms/ssrTransformElement'
import { SSRErrorCodes, createSSRCompilerError } from './errors'
// Because SSR codegen output is completely different from client-side output
// (e.g. multiple elements can be concatenated into a single template literal
// instead of each getting a corresponding call), we need to apply an extra
// transform pass to convert the template AST into a fresh JS AST before
// passing it to codegen.
export function ssrCodegenTransform(
ast: RootNode,
options: CompilerOptions,
): void {
const context = createSSRTransformContext(ast, options)
// inject SFC <style> CSS variables
// we do this instead of inlining the expression to ensure the vars are
// only resolved once per render
if (options.ssrCssVars) {
const cssContext = createTransformContext(createRoot([]), options)
const varsExp = processExpression(
createSimpleExpression(options.ssrCssVars, false),
cssContext,
)
context.body.push(
createCompoundExpression([`const _cssVars = { style: `, varsExp, `}`]),
)
Array.from(cssContext.helpers.keys()).forEach(helper => {
ast.helpers.add(helper)
})
}
const isFragment =
ast.children.length > 1 && ast.children.some(c => !isText(c))
processChildren(ast, context, isFragment)
ast.codegenNode = createBlockStatement(context.body)
// Finalize helpers.
// We need to separate helpers imported from 'vue' vs. '@vue/server-renderer'
ast.ssrHelpers = Array.from(
new Set([
...Array.from(ast.helpers).filter(h => h in ssrHelpers),
...context.helpers,
]),
)
ast.helpers = new Set(Array.from(ast.helpers).filter(h => !(h in ssrHelpers)))
}
export interface SSRTransformContext {
root: RootNode
options: CompilerOptions
body: (JSChildNode | IfStatement)[]
helpers: Set<symbol>
withSlotScopeId: boolean
onError: (error: CompilerError) => void
helper<T extends symbol>(name: T): T
pushStringPart(part: TemplateLiteral['elements'][0]): void
pushStatement(statement: IfStatement | CallExpression): void
}
function createSSRTransformContext(
root: RootNode,
options: CompilerOptions,
helpers: Set<symbol> = new Set(),
withSlotScopeId = false,
): SSRTransformContext {
const body: BlockStatement['body'] = []
let currentString: TemplateLiteral | null = null
return {
root,
options,
body,
helpers,
withSlotScopeId,
onError:
options.onError ||
(e => {
throw e
}),
helper<T extends symbol>(name: T): T {
helpers.add(name)
return name
},
pushStringPart(part) {
if (!currentString) {
const currentCall = createCallExpression(`_push`)
body.push(currentCall)
currentString = createTemplateLiteral([])
currentCall.arguments.push(currentString)
}
const bufferedElements = currentString.elements
const lastItem = bufferedElements[bufferedElements.length - 1]
if (isString(part) && isString(lastItem)) {
bufferedElements[bufferedElements.length - 1] += part
} else {
bufferedElements.push(part)
}
},
pushStatement(statement) {
// close current string
currentString = null
body.push(statement)
},
}
}
function createChildContext(
parent: SSRTransformContext,
withSlotScopeId = parent.withSlotScopeId,
): SSRTransformContext {
// ensure child inherits parent helpers
return createSSRTransformContext(
parent.root,
parent.options,
parent.helpers,
withSlotScopeId,
)
}
interface Container {
children: TemplateChildNode[]
}
export function processChildren(
parent: Container,
context: SSRTransformContext,
asFragment = false,
disableNestedFragments = false,
disableComment = false,
asDynamic = false,
): void {
if (asDynamic) {
context.pushStringPart(`<!--${DYNAMIC_START_ANCHOR_LABEL}-->`)
}
if (asFragment) {
context.pushStringPart(`<!--[-->`)
}
const { children, type, tagType } = parent as PlainElementNode
const inElement =
type === NodeTypes.ELEMENT && tagType === ElementTypes.ELEMENT
if (inElement) processChildrenDynamicInfo(children)
for (let i = 0; i < children.length; i++) {
const child = children[i]
if (inElement && shouldProcessChildAsDynamic(parent, child)) {
processChildren(
{ children: [child] },
context,
asFragment,
disableNestedFragments,
disableComment,
true,
)
continue
}
switch (child.type) {
case NodeTypes.ELEMENT:
switch (child.tagType) {
case ElementTypes.ELEMENT:
ssrProcessElement(child, context)
break
case ElementTypes.COMPONENT:
ssrProcessComponent(child, context, parent)
break
case ElementTypes.SLOT:
ssrProcessSlotOutlet(child, context)
break
case ElementTypes.TEMPLATE:
// TODO
break
default:
context.onError(
createSSRCompilerError(
SSRErrorCodes.X_SSR_INVALID_AST_NODE,
(child as any).loc,
),
)
// make sure we exhaust all possible types
const exhaustiveCheck: never = child
return exhaustiveCheck
}
break
case NodeTypes.TEXT:
context.pushStringPart(escapeHtml(child.content))
break
case NodeTypes.COMMENT:
// no need to escape comment here because the AST can only
// contain valid comments.
if (!disableComment) {
context.pushStringPart(`<!--${child.content}-->`)
}
break
case NodeTypes.INTERPOLATION:
context.pushStringPart(
createCallExpression(context.helper(SSR_INTERPOLATE), [
child.content,
]),
)
break
case NodeTypes.IF:
ssrProcessIf(child, context, disableNestedFragments, disableComment)
break
case NodeTypes.FOR:
ssrProcessFor(child, context, disableNestedFragments)
break
case NodeTypes.IF_BRANCH:
// no-op - handled by ssrProcessIf
break
case NodeTypes.TEXT_CALL:
case NodeTypes.COMPOUND_EXPRESSION:
// no-op - these two types can never appear as template child node since
// `transformText` is not used during SSR compile.
break
default:
context.onError(
createSSRCompilerError(
SSRErrorCodes.X_SSR_INVALID_AST_NODE,
(child as any).loc,
),
)
// make sure we exhaust all possible types
const exhaustiveCheck: never = child
return exhaustiveCheck
}
}
if (asFragment) {
context.pushStringPart(`<!--]-->`)
}
if (asDynamic) {
context.pushStringPart(`<!--${DYNAMIC_END_ANCHOR_LABEL}-->`)
}
}
export function processChildrenAsStatement(
parent: Container,
parentContext: SSRTransformContext,
asFragment = false,
withSlotScopeId: boolean = parentContext.withSlotScopeId,
): BlockStatement {
const childContext = createChildContext(parentContext, withSlotScopeId)
processChildren(parent, childContext, asFragment)
return createBlockStatement(childContext.body)
}
const isStaticChildNode = (c: TemplateChildNode): boolean =>
(c.type === NodeTypes.ELEMENT && c.tagType !== ElementTypes.COMPONENT) ||
c.type === NodeTypes.TEXT ||
c.type === NodeTypes.COMMENT
interface DynamicInfo {
hasStaticPrevious: boolean
hasStaticNext: boolean
prevDynamicCount: number
nextDynamicCount: number
}
function processChildrenDynamicInfo(
children: (TemplateChildNode & { _ssrDynamicInfo?: DynamicInfo })[],
): void {
const filteredChildren = children.filter(
child => !(child.type === NodeTypes.TEXT && !child.content.trim()),
)
for (let i = 0; i < filteredChildren.length; i++) {
const child = filteredChildren[i]
if (
isStaticChildNode(child) ||
// fragment has it's own anchor, which can be used to distinguish the boundary
isFragmentChild(child)
) {
continue
}
child._ssrDynamicInfo = {
hasStaticPrevious: false,
hasStaticNext: false,
prevDynamicCount: 0,
nextDynamicCount: 0,
}
const info = child._ssrDynamicInfo
// Calculate the previous static and dynamic node counts
let foundStaticPrev = false
let dynamicCountPrev = 0
for (let j = i - 1; j >= 0; j--) {
const prevChild = filteredChildren[j]
if (isStaticChildNode(prevChild)) {
foundStaticPrev = true
break
}
// if the previous child has dynamic info, use it
else if (prevChild._ssrDynamicInfo) {
foundStaticPrev = prevChild._ssrDynamicInfo.hasStaticPrevious
dynamicCountPrev = prevChild._ssrDynamicInfo.prevDynamicCount + 1
break
}
dynamicCountPrev++
}
info.hasStaticPrevious = foundStaticPrev
info.prevDynamicCount = dynamicCountPrev
// Calculate the number of static and dynamic nodes afterwards
let foundStaticNext = false
let dynamicCountNext = 0
for (let j = i + 1; j < filteredChildren.length; j++) {
const nextChild = filteredChildren[j]
if (isStaticChildNode(nextChild)) {
foundStaticNext = true
break
}
// if the next child has dynamic info, use it
else if (nextChild._ssrDynamicInfo) {
foundStaticNext = nextChild._ssrDynamicInfo.hasStaticNext
dynamicCountNext = nextChild._ssrDynamicInfo.nextDynamicCount + 1
break
}
dynamicCountNext++
}
info.hasStaticNext = foundStaticNext
info.nextDynamicCount = dynamicCountNext
}
}
/**
* Check if a node should be processed as dynamic child.
* This is primarily used in Vapor mode hydration to wrap dynamic parts
* with markers (`<!--[[-->` and `<!--]]-->`).
* The purpose is to distinguish the boundaries of nodes during vapor hydration
*
* 1. two consecutive dynamic nodes should only wrap the second one
* <element>
* <element/> // Static node
* <Comp/> // Dynamic node -> should NOT be wrapped
* <Comp/> // Dynamic node -> should be wrapped
* <element/> // Static node
* </element>
*
* 2. three or more consecutive dynamic nodes should only wrap the
* middle nodes, leaving the first and last static.
* <element>
* <element/> // Static node
* <Comp/> // Dynamic node -> should NOT be wrapped
* <Comp/> // Dynamic node -> should be wrapped
* <Comp/> // Dynamic node -> should be wrapped
* <Comp/> // Dynamic node -> should NOT be wrapped
* <element/> // Static node
* </element>
*/
function shouldProcessChildAsDynamic(
parent: { tag?: string; children: TemplateChildNode[] },
node: TemplateChildNode & { _ssrDynamicInfo?: DynamicInfo },
): boolean {
// must be inside a parent element
if (!parent.tag) return false
// must has dynamic info
const { _ssrDynamicInfo: info } = node
if (!info) return false
const {
hasStaticPrevious,
hasStaticNext,
prevDynamicCount,
nextDynamicCount,
} = info
// must have static nodes on both sides
if (!hasStaticPrevious || !hasStaticNext) return false
const dynamicNodeCount = 1 + prevDynamicCount + nextDynamicCount
// For two consecutive dynamic nodes, mark the second one as dynamic
if (dynamicNodeCount === 2) {
return prevDynamicCount > 0
}
// For three or more dynamic nodes, mark the intermediate node as dynamic
else if (dynamicNodeCount >= 3) {
return prevDynamicCount > 0 && nextDynamicCount > 0
}
return false
}
function isFragmentChild(child: TemplateChildNode): boolean {
const { type } = child
return type === NodeTypes.IF || type === NodeTypes.FOR
}