Function extractNamespaceFromUseStatement

tools/stylelint/no-unused-import.ts:63–98

Extracts the namespace of an `@use` rule from its parameters.

(params: string)

/** Extracts the namespace of an `@use` rule from its parameters.  */
function extractNamespaceFromUseStatement(params: string): string | null {
  const openQuoteIndex = Math.max(params.indexOf(`"`), params.indexOf(`'`));
  const closeQuoteIndex = Math.max(
    params.indexOf(`"`, openQuoteIndex + 1),
    params.indexOf(`'`, openQuoteIndex + 1),
  );

  if (closeQuoteIndex > -1) {
    const asExpression = 'as ';
    const asIndex = params.indexOf(asExpression, closeQuoteIndex);
    const withIndex = params.indexOf(' with', asIndex);

    // If we found an ` as ` expression, we consider the rest of the text as the namespace.
    if (asIndex > -1) {
      return withIndex == -1
        ? params.slice(asIndex + asExpression.length).trim()
        : params.slice(asIndex + asExpression.length, withIndex).trim();
    }

    const importPath = params
      .slice(openQuoteIndex + 1, closeQuoteIndex)
      // Sass allows for leading underscores to be omitted and it technically supports .scss.
      .replace(/^_|\.scss$/g, '');

    // Built-in Sass imports look like `sass:map`.
    if (importPath.startsWith('sass:')) {
      return importPath.split('sass:')[1];
    }

    // Sass ignores `/index` and infers the namespace as the next segment in the path.
    const fileName = basename(importPath);
    return fileName === 'index' ? basename(join(fileName, '..')) : fileName;
  }

  return null;
}

export default createPlugin(ruleName, ruleFn);