import { parse, ParserPlugin } from '@babel/parser'
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import MagicString from 'magic-string'
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const defaultExportRE = /((?:^|\n|;)\s*)export(\s*)default/
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const namedDefaultExportRE = /((?:^|\n|;)\s*)export(.+)(?:as)?(\s*)default/s
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const exportDefaultClassRE =
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/((?:^|\n|;)\s*)export\s+default\s+class\s+([\w$]+)/
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/**
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* Utility for rewriting `export default` in a script block into a variable
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* declaration so that we can inject things into it
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*/
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export function rewriteDefault(
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input: string,
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as: string,
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parserPlugins?: ParserPlugin[]
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): string {
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if (!hasDefaultExport(input)) {
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return input + `\nconst ${as} = {}`
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}
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let replaced: string | undefined
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const classMatch = input.match(exportDefaultClassRE)
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if (classMatch) {
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replaced =
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input.replace(exportDefaultClassRE, '$1class $2') +
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`\nconst ${as} = ${classMatch[2]}`
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} else {
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replaced = input.replace(defaultExportRE, `$1const ${as} =`)
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}
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if (!hasDefaultExport(replaced)) {
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return replaced
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}
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// if the script somehow still contains `default export`, it probably has
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// multi-line comments or template strings. fallback to a full parse.
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const s = new MagicString(input)
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const ast = parse(input, {
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sourceType: 'module',
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plugins: parserPlugins
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}).program.body
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ast.forEach(node => {
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if (node.type === 'ExportDefaultDeclaration') {
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if (node.declaration.type === 'ClassDeclaration' && node.declaration.id) {
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let start: number =
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node.declaration.decorators && node.declaration.decorators.length > 0
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? node.declaration.decorators[
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node.declaration.decorators.length - 1
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].end!
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: node.start!
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s.overwrite(start, node.declaration.id.start!, ` class `)
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s.append(`\nconst ${as} = ${node.declaration.id.name}`)
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} else {
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s.overwrite(node.start!, node.declaration.start!, `const ${as} = `)
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}
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}
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if (node.type === 'ExportNamedDeclaration') {
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for (const specifier of node.specifiers) {
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if (
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specifier.type === 'ExportSpecifier' &&
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specifier.exported.type === 'Identifier' &&
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specifier.exported.name === 'default'
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) {
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if (node.source) {
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if (specifier.local.name === 'default') {
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const end = specifierEnd(input, specifier.local.end!, node.end)
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s.prepend(
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`import { default as __VUE_DEFAULT__ } from '${node.source.value}'\n`
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)
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s.overwrite(specifier.start!, end, ``)
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s.append(`\nconst ${as} = __VUE_DEFAULT__`)
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continue
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} else {
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const end = specifierEnd(input, specifier.exported.end!, node.end)
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s.prepend(
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`import { ${input.slice(
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specifier.local.start!,
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specifier.local.end!
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)} } from '${node.source.value}'\n`
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)
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s.overwrite(specifier.start!, end, ``)
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s.append(`\nconst ${as} = ${specifier.local.name}`)
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continue
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}
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}
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const end = specifierEnd(input, specifier.end!, node.end)
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s.overwrite(specifier.start!, end, ``)
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s.append(`\nconst ${as} = ${specifier.local.name}`)
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}
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}
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}
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})
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return s.toString()
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}
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export function hasDefaultExport(input: string): boolean {
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return defaultExportRE.test(input) || namedDefaultExportRE.test(input)
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}
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function specifierEnd(
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input: string,
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end: number,
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nodeEnd: number | undefined | null
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) {
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// export { default , foo } ...
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let hasCommas = false
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let oldEnd = end
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while (end < nodeEnd!) {
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if (/\s/.test(input.charAt(end))) {
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end++
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} else if (input.charAt(end) === ',') {
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end++
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hasCommas = true
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break
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} else if (input.charAt(end) === '}') {
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break
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}
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}
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return hasCommas ? end : oldEnd
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}
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