mirror of https://github.com/vuejs/core.git
79 lines
2.1 KiB
TypeScript
79 lines
2.1 KiB
TypeScript
import {
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type BlockStatement,
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type IfBranchNode,
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type IfNode,
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type NodeTransform,
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NodeTypes,
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createBlockStatement,
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createCallExpression,
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createIfStatement,
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createStructuralDirectiveTransform,
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processIf,
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} from '@vue/compiler-dom'
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import {
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type SSRTransformContext,
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processChildrenAsStatement,
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} from '../ssrCodegenTransform'
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// Plugin for the first transform pass, which simply constructs the AST node
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export const ssrTransformIf: NodeTransform = createStructuralDirectiveTransform(
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/^(if|else|else-if)$/,
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processIf,
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)
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// This is called during the 2nd transform pass to construct the SSR-specific
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// codegen nodes.
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export function ssrProcessIf(
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node: IfNode,
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context: SSRTransformContext,
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disableNestedFragments = false,
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disableCommentAsIfAlternate = false,
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): void {
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const [rootBranch] = node.branches
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const ifStatement = createIfStatement(
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rootBranch.condition!,
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processIfBranch(rootBranch, context, disableNestedFragments),
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)
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context.pushStatement(ifStatement)
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let currentIf = ifStatement
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for (let i = 1; i < node.branches.length; i++) {
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const branch = node.branches[i]
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const branchBlockStatement = processIfBranch(
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branch,
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context,
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disableNestedFragments,
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)
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if (branch.condition) {
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// else-if
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currentIf = currentIf.alternate = createIfStatement(
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branch.condition,
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branchBlockStatement,
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)
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} else {
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// else
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currentIf.alternate = branchBlockStatement
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}
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}
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if (!currentIf.alternate && !disableCommentAsIfAlternate) {
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currentIf.alternate = createBlockStatement([
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createCallExpression(`_push`, ['`<!---->`']),
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])
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}
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}
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function processIfBranch(
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branch: IfBranchNode,
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context: SSRTransformContext,
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disableNestedFragments = false,
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): BlockStatement {
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const { children } = branch
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const needFragmentWrapper =
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!disableNestedFragments &&
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(children.length !== 1 || children[0].type !== NodeTypes.ELEMENT) &&
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// optimize away nested fragments when the only child is a ForNode
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!(children.length === 1 && children[0].type === NodeTypes.FOR)
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return processChildrenAsStatement(branch, context, needFragmentWrapper)
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}
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