loader-plugin.ts

import type { LoadResult, Plugin, ResolveIdResult } from 'rollup';

/**
 * Rollup plugin that aids in resolving the entry points (1 or more files) for a Stencil project. For example, a project
 * using the `dist-custom-elements` output target may have a single 'entry point' for each file containing a component.
 * Each of those files will be independently resolved and loaded by this plugin for further processing by Rollup later
 * in the bundling process.
 *
 * @param entries the Stencil project files to process. It should be noted that the keys in this object may not
 * necessarily be an absolute or relative path to a file, but may be a Rollup Virtual Module (which begin with \0).
 * @returns the rollup plugin that loads and process a Stencil project's entry points
 */
export const loaderPlugin = (entries: { [id: string]: string } = {}): Plugin => {
  return {
    name: 'stencilLoaderPlugin',
    /**
     * A rollup build hook for resolving the imports of individual Stencil project files. This hook only resolves
     * modules that are contained in the plugin's `entries` argument. [Source](https://rollupjs.org/guide/en/#resolveid)
     * @param id the importee to resolve
     * @returns a string that resolves an import to some id, null otherwise
     */
    resolveId(id: string): ResolveIdResult {
      if (id in entries) {
        return {
          id,
        };
      }
      return null;
    },
    /**
     * A rollup build hook for loading individual Stencil project files [Source](https://rollupjs.org/guide/en/#load)
     * @param id the path of the module to load. It should be noted that the keys in this object may not necessarily
     * be an absolute or relative path to a file, but may be a Rollup Virtual Module.
     * @returns the module matched, null otherwise
     */
    load(id: string): LoadResult {
      if (id in entries) {
        return entries[id];
      }
      return null;
    },
  };
};