rewrite options handling to be MUCH more maintainable and less like spaghetti

src/babel/helpers/merge.js

@@ -3,8 +3,8 @@ import merge from "lodash/object/merge";
 export default function (dest, src) {
   if (!dest || !src) return;
 
-  return merge(dest, src, function(a, b) {
-    if (Array.isArray(a)) {
+  return merge(dest, src, function (a, b) {
+    if (b && Array.isArray(a)) {
       var c = a.slice(0);
       for (var v of b) {
         if (a.indexOf(v) < 0) {

src/babel/transformation/file/index.js

@@ -1,25 +1,20 @@
-import { validateOption, normaliseOptions, config as optionsConfig } from "./options";
 import convertSourceMap from "convert-source-map";
 import moduleFormatters from "../modules";
+import OptionManager from "./options/option-manager";
 import PluginManager from "./plugin-manager";
 import shebangRegex from "shebang-regex";
 import NodePath from "../../traversal/path";
 import isFunction from "lodash/lang/isFunction";
-import isAbsolute from "path-is-absolute";
-import resolveRc from "./options/resolve-rc";
 import sourceMap from "source-map";
 import generate from "../../generation";
 import codeFrame from "../../helpers/code-frame";
 import defaults from "lodash/object/defaults";
 import includes from "lodash/collection/includes";
 import traverse from "../../traversal";
-import assign from "lodash/object/assign";
 import Logger from "./logger";
 import Plugin from "../plugin";
 import parse from "../../helpers/parse";
-import merge from "../../helpers/merge";
 import slash from "slash";
-import clone from "lodash/lang/clone";
 import Hub from "../../traversal/hub";
 import * as util from  "../../util";
 import path from "path";
@@ -50,10 +45,9 @@ export default class File {
 
     this.pipeline = pipeline;
     this.log      = new Logger(this, opts.filename || "unknown");
+    this.opts     = this.initOptions(opts);
     this.ast      = {};
 
-    this.normaliseOptions(opts);
-
     this.buildTransformers();
 
     this.hub = new Hub(this);
@@ -98,56 +92,8 @@ export default class File {
 
   static soloHelpers = [];
 
-  static options = optionsConfig;
-
-  normaliseOptions(opts: Object) {
-    opts = this.opts = normaliseOptions(assign({}, opts));
-
-    // resolve babelrc
-    if (opts.filename) {
-      var rcFilename = opts.filename;
-      if (!isAbsolute(rcFilename)) rcFilename = path.join(process.cwd(), rcFilename);
-      opts = resolveRc(rcFilename, opts);
-    }
-
-    // check for unknown options
-    for (let key in opts) {
-      if (key[0] === "_") continue;
-
-      let option = File.options[key];
-      if (!option) this.log.error(`Unknown option: ${key}`, ReferenceError);
-    }
-
-    // merge in environment options
-    var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
-    if (opts.env) merge(opts, normaliseOptions(opts.env[envKey]));
-
-    // normalise options
-    for (let key in File.options) {
-      let option = File.options[key];
-      var val    = opts[key];
-
-      // optional
-      if (!val && option.optional) continue;
-
-      // deprecated
-      if (val && option.deprecated) {
-        this.log.deprecate("Deprecated option " + key + ": " + option.deprecated);
-      }
-
-      // default
-      if (val == null) val = clone(option.default);
-
-      // validate
-      if (val) val = validateOption(key, val, this.pipeline);
-
-      // aaliases
-      if (option.alias) {
-        opts[option.alias] = opts[option.alias] || val;
-      } else {
-        opts[key] = val;
-      }
-    }
+  initOptions(opts) {
+    opts = new OptionManager(this.log, this.pipeline).init(opts);
 
     if (opts.inputSourceMap) {
       opts.sourceMaps = true;
@@ -195,7 +141,7 @@ export default class File {
     }
 
     return opts;
-  };
+  }
 
   isLoose(key: string) {
     return includes(this.opts.loose, key);

src/babel/transformation/file/options/config.json

@@ -253,7 +253,7 @@
   },
 
   "babelrc": {
-    "hidden": true,
-    "description": "do not load the same .babelrc file twice"
+    "description": "Specify a custom list of babelrc files to use",
+    "type": "list"
   }
 }

src/babel/transformation/file/options/option-manager.js

@@ -0,0 +1,168 @@
+import stripJsonComments from "strip-json-comments";
+import { validateOption, normaliseOptions } from "./index";
+import isAbsolute from "path-is-absolute";
+import clone from "lodash/lang/clone";
+import merge from "../../../helpers/merge";
+import config from "./config";
+import path from "path";
+import fs from "fs";
+import pathExists from "path-exists";
+
+var existsCache = {};
+var jsonCache   = {};
+
+const CONFIG_FILENAME = ".babelrc";
+
+function exists(filename) {
+  var cached = existsCache[filename];
+  if (cached != null) {
+    return cached;
+  } else {
+    return existsCache[filename] = pathExists.sync(filename);
+  }
+}
+
+export default class OptionManager {
+  constructor(log, pipeline) {
+    this.resolvedConfigs = [];
+    this.options         = OptionManager.createBareOptions();
+    this.pipeline        = pipeline;
+    this.log             = log;
+  }
+
+  /**
+   * Description
+   */
+
+  static createBareOptions() {
+    var opts = {};
+
+    for (var key in config) {
+      var opt = config[key];
+      opts[key] = clone(opt.default);
+    }
+
+    return opts;
+  }
+
+  /**
+   * Description
+   */
+
+  addConfig(loc) {
+    if (this.resolvedConfigs.indexOf(loc) >= 0) return;
+
+    var content = fs.readFileSync(loc, "utf8");
+    var opts;
+
+    try {
+      opts = jsonCache[content] = jsonCache[content] || JSON.parse(stripJsonComments(content));
+    } catch (err) {
+      err.message = `${loc}: ${err.message}`;
+      throw err;
+    }
+
+    this.mergeOptions(opts, loc);
+    this.resolvedConfigs.push(loc);
+  }
+
+  /**
+   * Description
+   */
+
+  mergeOptions(opts, alias) {
+    if (!opts) return;
+
+    for (let key in opts) {
+      if (key[0] === "_") continue;
+
+      let option = config[key];
+
+      // check for an unknown option
+      if (!option) this.log.error(`Unknown option: ${alias}.${key}`, ReferenceError);
+    }
+
+    // normalise options
+    normaliseOptions(opts);
+
+    // merge them into this current files options
+    merge(this.options, opts);
+  }
+
+  /**
+   * Description
+   */
+
+  findConfigs(loc) {
+    if (!loc) return;
+
+    if (!isAbsolute(loc)) {
+      loc = path.join(process.cwd(), loc);
+    }
+
+    while (loc !== (loc = path.dirname(loc))) {
+      if (this.options.breakConfig) return;
+
+      var configLoc = path.join(loc, CONFIG_FILENAME);
+      if (exists(configLoc)) this.addConfig(configLoc);
+    }
+  }
+
+  /**
+   * Description
+   */
+
+  normaliseOptions() {
+    var opts = this.options;
+
+    for (let key in config) {
+      var option = config[key];
+      var val    = opts[key];
+
+      // optional
+      if (!val && option.optional) continue;
+
+      // deprecated
+      if (val && option.deprecated) {
+        this.log.deprecate(`Deprecated option ${key}: ${option.deprecated}`);
+      }
+
+      // validate
+      if (val) val = validateOption(key, val, this.pipeline);
+
+      // aaliases
+      if (option.alias) {
+        opts[option.alias] = opts[option.alias] || val;
+      } else {
+        opts[key] = val;
+      }
+    }
+  }
+
+  /**
+   * Description
+   */
+
+  init(opts) {
+    this.mergeOptions(opts, "direct");
+
+    // babelrc option
+    if (opts.babelrc) {
+      for (var loc of (opts.babelrc: Array)) this.addConfig(loc);
+    }
+
+    // resolve all .babelrc files
+    this.findConfigs(opts.filename);
+
+    // merge in env
+    var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
+    if (this.options.env) {
+      this.mergeOptions(this.options.env[envKey], `direct.env.${envKey}`);
+    }
+
+    // normalise
+    this.normaliseOptions(opts);
+
+    return this.options;
+  }
+}

src/babel/transformation/file/options/resolve-rc.js

@@ -1,61 +0,0 @@
-import stripJsonComments from "strip-json-comments";
-import { normaliseOptions } from "./index";
-import merge from "../../../helpers/merge";
-import path from "path";
-import fs from "fs";
-import pathExists from "path-exists";
-
-var cache = {};
-var jsons = {};
-
-function exists(filename) {
-  var cached = cache[filename];
-  if (cached != null) return cached;
-  return cache[filename] = pathExists.sync(filename);
-}
-
-export default function (loc, opts = {}) {
-  var rel = ".babelrc";
-
-  if (!opts.babelrc) {
-    opts.babelrc = [];
-  }
-
-  function find(start, rel) {
-    var file = path.join(start, rel);
-
-    if (opts.babelrc.indexOf(file) >= 0) {
-      return;
-    }
-
-    if (exists(file)) {
-      var content = fs.readFileSync(file, "utf8");
-      var json;
-
-      try {
-        json = jsons[content] = jsons[content] || JSON.parse(stripJsonComments(content));
-        normaliseOptions(json);
-      } catch (err) {
-        err.message = `${file}: ${err.message}`;
-        throw err;
-      }
-
-      opts.babelrc.push(file);
-
-      if (json.breakConfig) return;
-
-      merge(opts, json);
-    }
-
-    var up = path.dirname(start);
-    if (up !== start) { // root
-      find(up, rel);
-    }
-  }
-
-  if (opts.babelrc.indexOf(loc) < 0 && opts.breakConfig !== true) {
-    find(loc, rel);
-  }
-
-  return opts;
-}