60 lines
1.8 KiB
TypeScript
60 lines
1.8 KiB
TypeScript
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/
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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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const replaced = input.replace(defaultExportRE, `$1const ${as} =`)
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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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s.overwrite(node.start!, node.declaration.start!, `const ${as} = `)
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}
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if (node.type === 'ExportNamedDeclaration') {
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node.specifiers.forEach(specifier => {
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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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const end = specifier.end!
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s.overwrite(
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specifier.start!,
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input.charAt(end) === ',' ? end + 1 : end,
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``
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)
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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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