packages/babel-core/src/config/files/configuration.js
// @flow
import buildDebug from "debug";
import path from "path";
import json5 from "json5";
import gensync, { type Handler } from "gensync";
import {
makeStrongCache,
makeWeakCacheSync,
type CacheConfigurator,
} from "../caching";
import makeAPI, { type PluginAPI } from "../helpers/config-api";
import { makeStaticFileCache } from "./utils";
import loadCjsOrMjsDefault from "./module-types";
import pathPatternToRegex from "../pattern-to-regex";
import type { FilePackageData, RelativeConfig, ConfigFile } from "./types";
import type { CallerMetadata } from "../validation/options";
import * as fs from "../../gensync-utils/fs";
import resolve from "../../gensync-utils/resolve";
const debug = buildDebug("babel:config:loading:files:configuration");
export const ROOT_CONFIG_FILENAMES = [
"babel.config.js",
"babel.config.cjs",
"babel.config.mjs",
"babel.config.json",
];
const RELATIVE_CONFIG_FILENAMES = [
".babelrc",
".babelrc.js",
".babelrc.cjs",
".babelrc.mjs",
".babelrc.json",
];
const BABELIGNORE_FILENAME = ".babelignore";
export function* findConfigUpwards(rootDir: string): Handler<string | null> {
let dirname = rootDir;
while (true) {
for (const filename of ROOT_CONFIG_FILENAMES) {
if (yield* fs.exists(path.join(dirname, filename))) {
return dirname;
}
}
const nextDir = path.dirname(dirname);
if (dirname === nextDir) break;
dirname = nextDir;
}
return null;
}
export function* findRelativeConfig(
packageData: FilePackageData,
envName: string,
caller: CallerMetadata | void,
): Handler<RelativeConfig> {
let config = null;
let ignore = null;
const dirname = path.dirname(packageData.filepath);
for (const loc of packageData.directories) {
if (!config) {
config = yield* loadOneConfig(
RELATIVE_CONFIG_FILENAMES,
loc,
envName,
caller,
packageData.pkg?.dirname === loc
? // $FlowIgnore - packageData.pkg is not null
packageToBabelConfig((packageData.pkg: ConfigFile))
: null,
);
}
if (!ignore) {
const ignoreLoc = path.join(loc, BABELIGNORE_FILENAME);
ignore = yield* readIgnoreConfig(ignoreLoc);
if (ignore) {
debug("Found ignore %o from %o.", ignore.filepath, dirname);
}
}
}
return { config, ignore };
}
export function findRootConfig(
dirname: string,
envName: string,
caller: CallerMetadata | void,
): Handler<ConfigFile | null> {
return loadOneConfig(ROOT_CONFIG_FILENAMES, dirname, envName, caller);
}
function* loadOneConfig(
names: string[],
dirname: string,
envName: string,
caller: CallerMetadata | void,
previousConfig?: ConfigFile | null = null,
): Handler<ConfigFile | null> {
const configs = yield* gensync.all(
names.map(filename =>
readConfig(path.join(dirname, filename), envName, caller),
),
);
const config = configs.reduce((previousConfig: ConfigFile | null, config) => {
if (config && previousConfig) {
throw new Error(
`Multiple configuration files found. Please remove one:\n` +
` - ${path.basename(previousConfig.filepath)}\n` +
` - ${config.filepath}\n` +
`from ${dirname}`,
);
}
return config || previousConfig;
}, previousConfig);
if (config) {
debug("Found configuration %o from %o.", config.filepath, dirname);
}
return config;
}
export function* loadConfig(
name: string,
dirname: string,
envName: string,
caller: CallerMetadata | void,
): Handler<ConfigFile> {
const filepath = yield* resolve(name, { basedir: dirname });
const conf = yield* readConfig(filepath, envName, caller);
if (!conf) {
throw new Error(`Config file ${filepath} contains no configuration data`);
}
debug("Loaded config %o from %o.", name, dirname);
return conf;
}
/**
* Read the given config file, returning the result. Returns null if no config was found, but will
* throw if there are parsing errors while loading a config.
*/
function readConfig(filepath, envName, caller) {
const ext = path.extname(filepath);
return ext === ".js" || ext === ".cjs" || ext === ".mjs"
? readConfigJS(filepath, { envName, caller })
: readConfigJSON5(filepath);
}
const LOADING_CONFIGS = new Set();
const readConfigJS = makeStrongCache(function* readConfigJS(
filepath: string,
cache: CacheConfigurator<{
envName: string,
caller: CallerMetadata | void,
}>,
): Handler<ConfigFile | null> {
if (!fs.exists.sync(filepath)) {
cache.forever();
return null;
}
// The `require()` call below can make this code reentrant if a require hook like @babel/register has been
// loaded into the system. That would cause Babel to attempt to compile the `.babelrc.js` file as it loads
// below. To cover this case, we auto-ignore re-entrant config processing.
if (LOADING_CONFIGS.has(filepath)) {
cache.never();
debug("Auto-ignoring usage of config %o.", filepath);
return {
filepath,
dirname: path.dirname(filepath),
options: {},
};
}
let options: mixed;
try {
LOADING_CONFIGS.add(filepath);
options = (yield* loadCjsOrMjsDefault(
filepath,
"You appear to be using a native ECMAScript module configuration " +
"file, which is only supported when running Babel asynchronously.",
): mixed);
} catch (err) {
err.message = `${filepath}: Error while loading config - ${err.message}`;
throw err;
} finally {
LOADING_CONFIGS.delete(filepath);
}
let assertCache = false;
if (typeof options === "function") {
yield* []; // if we want to make it possible to use async configs
options = ((options: any): (api: PluginAPI) => {})(makeAPI(cache));
assertCache = true;
}
if (!options || typeof options !== "object" || Array.isArray(options)) {
throw new Error(
`${filepath}: Configuration should be an exported JavaScript object.`,
);
}
if (typeof options.then === "function") {
throw new Error(
`You appear to be using an async configuration, ` +
`which your current version of Babel does not support. ` +
`We may add support for this in the future, ` +
`but if you're on the most recent version of @babel/core and still ` +
`seeing this error, then you'll need to synchronously return your config.`,
);
}
if (assertCache && !cache.configured()) throwConfigError();
return {
filepath,
dirname: path.dirname(filepath),
options,
};
});
const packageToBabelConfig = makeWeakCacheSync(
(file: ConfigFile): ConfigFile | null => {
const babel = file.options[("babel": string)];
if (typeof babel === "undefined") return null;
if (typeof babel !== "object" || Array.isArray(babel) || babel === null) {
throw new Error(`${file.filepath}: .babel property must be an object`);
}
return {
filepath: file.filepath,
dirname: file.dirname,
options: babel,
};
},
);
const readConfigJSON5 = makeStaticFileCache((filepath, content) => {
let options;
try {
options = json5.parse(content);
} catch (err) {
err.message = `${filepath}: Error while parsing config - ${err.message}`;
throw err;
}
if (!options) throw new Error(`${filepath}: No config detected`);
if (typeof options !== "object") {
throw new Error(`${filepath}: Config returned typeof ${typeof options}`);
}
if (Array.isArray(options)) {
throw new Error(`${filepath}: Expected config object but found array`);
}
return {
filepath,
dirname: path.dirname(filepath),
options,
};
});
const readIgnoreConfig = makeStaticFileCache((filepath, content) => {
const ignoreDir = path.dirname(filepath);
const ignorePatterns = content
.split("\n")
.map(line => line.replace(/#(.*?)$/, "").trim())
.filter(line => !!line);
for (const pattern of ignorePatterns) {
if (pattern[0] === "!") {
throw new Error(`Negation of file paths is not supported.`);
}
}
return {
filepath,
dirname: path.dirname(filepath),
ignore: ignorePatterns.map(pattern =>
pathPatternToRegex(pattern, ignoreDir),
),
};
});
function throwConfigError() {
throw new Error(`\
Caching was left unconfigured. Babel's plugins, presets, and .babelrc.js files can be configured
for various types of caching, using the first param of their handler functions:
module.exports = function(api) {
// The API exposes the following:
// Cache the returned value forever and don't call this function again.
api.cache(true);
// Don't cache at all. Not recommended because it will be very slow.
api.cache(false);
// Cached based on the value of some function. If this function returns a value different from
// a previously-encountered value, the plugins will re-evaluate.
var env = api.cache(() => process.env.NODE_ENV);
// If testing for a specific env, we recommend specifics to avoid instantiating a plugin for
// any possible NODE_ENV value that might come up during plugin execution.
var isProd = api.cache(() => process.env.NODE_ENV === "production");
// .cache(fn) will perform a linear search though instances to find the matching plugin based
// based on previous instantiated plugins. If you want to recreate the plugin and discard the
// previous instance whenever something changes, you may use:
var isProd = api.cache.invalidate(() => process.env.NODE_ENV === "production");
// Note, we also expose the following more-verbose versions of the above examples:
api.cache.forever(); // api.cache(true)
api.cache.never(); // api.cache(false)
api.cache.using(fn); // api.cache(fn)
// Return the value that will be cached.
return { };
};`);
}