fix polluting globals

.changeset/twelve-fireants-retire.md

@@ -0,0 +1,5 @@
+---
+'mdxts': patch
+---
+
+Fixes polluting `CodeBlock` globals by always adding a `export { }` declaration to the AST and only removing it from the rendered tokens.

packages/mdxts/src/components/CodeBlock/get-tokens.ts

@@ -118,19 +118,33 @@ export async function getTokens(
     allowedErrorCodes.length === 0 && allowErrors
       ? []
       : sourceFile
-        ? getDiagnostics(sourceFile).filter(
-            (diagnostic) => !allowedErrorCodes.includes(diagnostic.getCode())
-          )
+        ? sourceFile
+            .getPreEmitDiagnostics()
+            .filter(
+              (diagnostic) => !allowedErrorCodes.includes(diagnostic.getCode())
+            )
         : []
   const theme = getThemeColors()
   const finalLanguage = getLanguage(language)
-  const { tokens } = highlighter.codeToTokens(
+  let { tokens } = highlighter.codeToTokens(
     sourceFile ? sourceFile.getFullText() : value,
     {
       theme: 'mdxts',
       lang: finalLanguage as any,
     }
   )
+  // If tokens contain an "export { }" statement, remove it
+  const exportStatementIndex = tokens.findIndex((line) =>
+    line
+      .map((token) => token.content)
+      .join('')
+      .includes('export { }')
+  )
+  if (exportStatementIndex > -1) {
+    // trim the export statement and the following line break
+    tokens = tokens.slice(0, exportStatementIndex - 1)
+  }
+
   const importSpecifiers =
     sourceFile && !jsxOnly
       ? sourceFile
@@ -323,26 +337,6 @@ function getQuickInfo(
   }
 }
 
-/** Get the diagnostics for a source file, coerced into a module if necessary. */
-function getDiagnostics(sourceFile: SourceFile) {
-  // if no imports/exports are found, add an empty export to coerce the file into a module and not pollute the global scope
-  const hasImports = sourceFile.getImportDeclarations().length > 0
-  const hasExports = sourceFile.getExportDeclarations().length > 0
-
-  if (!hasImports && !hasExports) {
-    sourceFile.addExportDeclaration({})
-  }
-
-  const diagnostics = sourceFile.getPreEmitDiagnostics()
-
-  // remove the empty export
-  if (!hasImports && !hasExports) {
-    sourceFile.getExportDeclarations().at(0)!.remove()
-  }
-
-  return diagnostics
-}
-
 const FontStyle = {
   Italic: 1,
   Bold: 2,

packages/mdxts/src/components/CodeBlock/parse-source-text-metadata.ts

@@ -162,16 +162,26 @@ export async function parseSourceTextMetadata({
       // attempt to fix the removed imports and any other missing imports
       sourceFile.fixMissingImports()
 
+      const importDeclarations = sourceFile.getImportDeclarations()
+
       if (shouldEmitDiagnostics) {
         // remap relative module specifiers to package imports if possible
         // e.g. `import { getTheme } from '../../mdxts/src/components'` -> `import { getTheme } from 'mdxts/components'`
-        sourceFile.getImportDeclarations().forEach((importDeclaration) => {
+        importDeclarations.forEach((importDeclaration) => {
           if (importDeclaration.isModuleSpecifierRelative()) {
             const importSpecifier = getPathRelativeToPackage(importDeclaration)
             importDeclaration.setModuleSpecifier(importSpecifier)
           }
         })
       }
+
+      // If no imports or exports add an empty export declaration to coerce TypeScript to treat the file as a module
+      const hasImports = importDeclarations.length > 0
+      const hasExports = sourceFile.getExportDeclarations().length > 0
+
+      if (!hasImports && !hasExports) {
+        sourceFile.addExportDeclaration({})
+      }
     } catch (error) {
       if (error instanceof Error) {
         const workingDirectory = process.cwd()