hot-hook/build/src/dynamic_import_checker.js

Easy hot module reloading (HMR) for Node.js and ESM

import { readFile } from 'node:fs/promises';
import { parseImports } from 'parse-imports';
/**
 * This class is responsible for checking if a given specifier
 * is imported dynamically from a given parent file.
 * Otherwise we will throw an error since we cannot make the file reloadable
 *
 * We are caching the results to avoid reading the same file multiple times
 *
 * When no import is found for the given specifier we assume that it is imported using a dynamic specifier.
 */
export class DynamicImportChecker {
    cache = new Map();
    async ensureFileIsImportedDynamicallyFromParent(parentPath, specifier) {
        const cacheKey = parentPath;
        if (this.cache.has(cacheKey) && this.cache.get(cacheKey).has(specifier)) {
            return this.cache.get(cacheKey).get(specifier);
        }
        const parentCode = await readFile(parentPath, 'utf-8');
        const imports = [...(await parseImports(parentCode))];
        const matchingImport = imports.find((importStatement) => {
            return importStatement.moduleSpecifier.value === specifier;
        });
        const isFileDynamicallyImportedFromParent = matchingImport
            ? matchingImport.isDynamicImport
            : true;
        const currentCache = this.cache.get(cacheKey) ?? new Map();
        this.cache.set(cacheKey, currentCache.set(specifier, isFileDynamicallyImportedFromParent));
        return isFileDynamicallyImportedFromParent;
    }
    invalidateCache(key) {
        this.cache.delete(key);
    }
}