prettier-plugin-imports/src/utils/get-import-nodes-matched-group.ts

A prettier plugins to sort imports in provided RegEx order

import {
  THIRD_PARTY_MODULES_SPECIAL_WORD,
  TYPES_SPECIAL_WORD,
} from '../constants';
import type { ImportDeclaration } from '@babel/types';

const regexCache = new Map<string, RegExp>();
const cachedRegExp = (regExp: string) => {
  if (regexCache.has(regExp)) {
    return regexCache.get(regExp)!;
  }
  // Strip <TYPES> when creating regexp
  const result = new RegExp(regExp.replace(TYPES_SPECIAL_WORD, ''));
  regexCache.set(regExp, result);
  return result;
};

/**
 * Get the regexp group to keep the import nodes.
 *
 * This comes near the end of processing, after import declaration nodes have
 * been combined or exploded.
 *
 * @param node
 * @param importOrder A list of [regexp or special-word] groups (no separators)
 */
export const getImportNodesMatchedGroup = (
  node: ImportDeclaration,
  importOrder: string[],
) => {
  const includesTypesSpecialWord = importOrder.some((group) =>
    group.includes(TYPES_SPECIAL_WORD),
  );
  const groupWithRegExp = importOrder
    .map((group) => ({
      group,
      regExp: cachedRegExp(group),
    }))
    // Remove explicit bare <TYPES> group, we'll deal with that at the end similar to third party modules
    .filter(({ group }) => group !== TYPES_SPECIAL_WORD);

  for (const { group, regExp } of groupWithRegExp) {
    let matched = false;
    // Type imports need to be checked separately
    // Note: this does not include import specifiers, just declarations.
    if (group.includes(TYPES_SPECIAL_WORD)) {
      // Since we stripped <TYPES> above, this will have a regexp too, e.g. local types
      matched =
        node.importKind === 'type' && node.source.value.match(regExp) !== null;
    } else {
      // If <TYPES> is being used for any group, and this group doesn't have it, only look for value imports
      matched = includesTypesSpecialWord
        ? node.importKind !== 'type' && node.source.value.match(regExp) !== null
        : node.source.value.match(regExp) !== null;
    }

    if (matched) return group;
  }

  return node.importKind === 'type' && includesTypesSpecialWord
    ? TYPES_SPECIAL_WORD
    : THIRD_PARTY_MODULES_SPECIAL_WORD;
};