37 lines
1.0 KiB
TypeScript
37 lines
1.0 KiB
TypeScript
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import { parse, ParserPlugin } from '@babel/parser'
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import MagicString from 'magic-string'
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const defaultExportRE = /((?:^|\n|;)\s*)export default/
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/**
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* Utility for rewriting `export default` in a script block into a varaible
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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 (!defaultExportRE.test(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 (!defaultExportRE.test(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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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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})
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return s.toString()
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}
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