lib/src/package_config_json.dart - package_config - Git at Google

 // Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 import "dart:convert";
 import "dart:io";
 import "dart:typed_data";

 import "discovery.dart" show packageConfigJsonPath;
 import "errors.dart";
 import "package_config_impl.dart";
 import "packages_file.dart" as packages_file;
 import "util.dart";

 const String _configVersionKey = "configVersion";
 const String _packagesKey = "packages";
 const List<String> _topNames = [_configVersionKey, _packagesKey];
 const String _nameKey = "name";
 const String _rootUriKey = "rootUri";
 const String _packageUriKey = "packageUri";
 const String _languageVersionKey = "languageVersion";
 const List<String> _packageNames = [
   _nameKey,
   _rootUriKey,
   _packageUriKey,
   _languageVersionKey
 ];

 const String _generatedKey = "generated";
 const String _generatorKey = "generator";
 const String _generatorVersionKey = "generatorVersion";

 /// Reads a package configuration file.
 ///
 /// Detects whether the [file] is a version one `.packages` file or
 /// a version two `package_config.json` file.
 ///
 /// If the [file] is a `.packages` file and [preferNewest] is true,
 /// first checks whether there is an adjacent `.dart_tool/package_config.json`
 /// file, and if so, reads that instead.
 /// If [preferNewset] is false, the specified file is loaded even if it is
 /// a `.packages` file and there is an available `package_config.json` file.
 ///
 /// The file must exist and be a normal file.
 Future<PackageConfig> readAnyConfigFile(
     File file, bool preferNewest, void onError(Object error)) async {
   Uint8List bytes;
   try {
     bytes = await file.readAsBytes();
   } catch (e) {
     onError(e);
     return const SimplePackageConfig.empty();
   }
   int firstChar = firstNonWhitespaceChar(bytes);
   if (firstChar != $lbrace) {
     // Definitely not a JSON object, probably a .packages.
     if (preferNewest) {
       var alternateFile = File(
           pathJoin(dirName(file.path), ".dart_tool", "package_config.json"));
       if (alternateFile.existsSync()) {
         Uint8List /*?*/ bytes;
         try {
           bytes = await alternateFile.readAsBytes();
         } catch (e) {
           onError(e);
           return const SimplePackageConfig.empty();
         }
         if (bytes != null) {
           return parsePackageConfigBytes(bytes, alternateFile.uri, onError);
         }
       }
     }
     return packages_file.parse(bytes, file.uri, onError);
   }
   return parsePackageConfigBytes(bytes, file.uri, onError);
 }

 /// Like [readAnyConfigFile] but uses a URI and an optional loader.
 Future<PackageConfig> readAnyConfigFileUri(
     Uri file,
     Future<Uint8List /*?*/ > loader(Uri uri) /*?*/,
     void onError(Object error),
     bool preferNewest) async {
   if (file.isScheme("package")) {
     throw PackageConfigArgumentError(
         file, "file", "Must not be a package: URI");
   }
   if (loader == null) {
     if (file.isScheme("file")) {
       return readAnyConfigFile(File.fromUri(file), preferNewest, onError);
     }
     loader = defaultLoader;
   }
   Uint8List bytes;
   try {
     bytes = await loader(file);
   } catch (e) {
     onError(e);
     return const SimplePackageConfig.empty();
   }
   if (bytes == null) {
     onError(PackageConfigArgumentError(
         file.toString(), "file", "File cannot be read"));
     return const SimplePackageConfig.empty();
   }
   int firstChar = firstNonWhitespaceChar(bytes);
   if (firstChar != $lbrace) {
     // Definitely not a JSON object, probably a .packages.
     if (preferNewest) {
       // Check if there is a package_config.json file.
       var alternateFile = file.resolveUri(packageConfigJsonPath);
       Uint8List alternateBytes;
       try {
         alternateBytes = await loader(alternateFile);
       } catch (e) {
         onError(e);
         return const SimplePackageConfig.empty();
       }
       if (alternateBytes != null) {
         return parsePackageConfigBytes(alternateBytes, alternateFile, onError);
       }
     }
     return packages_file.parse(bytes, file, onError);
   }
   return parsePackageConfigBytes(bytes, file, onError);
 }

 Future<PackageConfig> readPackageConfigJsonFile(
     File file, void onError(Object error)) async {
   Uint8List bytes;
   try {
     bytes = await file.readAsBytes();
   } catch (error) {
     onError(error);
     return const SimplePackageConfig.empty();
   }
   return parsePackageConfigBytes(bytes, file.uri, onError);
 }

 Future<PackageConfig> readDotPackagesFile(
     File file, void onError(Object error)) async {
   Uint8List bytes;
   try {
     bytes = await file.readAsBytes();
   } catch (error) {
     onError(error);
     return const SimplePackageConfig.empty();
   }
   return packages_file.parse(bytes, file.uri, onError);
 }

 final _jsonUtf8Decoder = json.fuse(utf8).decoder;

 PackageConfig parsePackageConfigBytes(
     Uint8List bytes, Uri file, void onError(Object error)) {
   // TODO(lrn): Make this simpler. Maybe parse directly from bytes.
   var jsonObject;
   try {
     jsonObject = _jsonUtf8Decoder.convert(bytes);
   } on FormatException catch (e) {
     onError(PackageConfigFormatException(e.message, e.source, e.offset));
     return const SimplePackageConfig.empty();
   }
   return parsePackageConfigJson(jsonObject, file, onError);
 }

 /// Creates a [PackageConfig] from a parsed JSON-like object structure.
 ///
 /// The [json] argument must be a JSON object (`Map<String, dynamic>`)
 /// containing a `"configVersion"` entry with an integer value in the range
 /// 1 to [PackageConfig.maxVersion],
 /// and with a `"packages"` entry which is a JSON array (`List<dynamic>`)
 /// containing JSON objects which each has the following properties:
 ///
 /// * `"name"`: The package name as a string.
 /// * `"rootUri"`: The root of the package as a URI stored as a string.
 /// * `"packageUri"`: Optionally the root of for `package:` URI resolution
 ///     for the package, as a relative URI below the root URI
 ///     stored as a string.
 /// * `"languageVersion"`: Optionally a language version string which is a
 ///     an integer numeral, a decimal point (`.`) and another integer numeral,
 ///     where the integer numeral cannot have a sign, and can only have a
 ///     leading zero if the entire numeral is a single zero.
 ///
 /// All other properties are stored in [extraData].
 ///
 /// The [baseLocation] is used as base URI to resolve the "rootUri"
 /// URI referencestring.
 PackageConfig parsePackageConfigJson(
     dynamic json, Uri baseLocation, void onError(Object error)) {
   if (!baseLocation.hasScheme || baseLocation.isScheme("package")) {
     throw PackageConfigArgumentError(baseLocation.toString(), "baseLocation",
         "Must be an absolute non-package: URI");
   }

   if (!baseLocation.path.endsWith("/")) {
     baseLocation = baseLocation.resolveUri(Uri(path: "."));
   }

   String typeName<T>() {
     if (0 is T) return "int";
     if ("" is T) return "string";
     if (const [] is T) return "array";
     return "object";
   }

   T checkType<T>(dynamic value, String name, [String /*?*/ packageName]) {
     if (value is T) return value;
     // The only types we are called with are [int], [String], [List<dynamic>]
     // and Map<String, dynamic>. Recognize which to give a better error message.
     var message =
         "$name${packageName != null ? " of package $packageName" : ""}"
         " is not a JSON ${typeName<T>()}";
     onError(PackageConfigFormatException(message, value));
     return null;
   }

   Package /*?*/ parsePackage(Map<String, dynamic> entry) {
     String /*?*/ name;
     String /*?*/ rootUri;
     String /*?*/ packageUri;
     String /*?*/ languageVersion;
     Map<String, dynamic> /*?*/ extraData;
     bool hasName = false;
     bool hasRoot = false;
     bool hasVersion = false;
     entry.forEach((key, value) {
       switch (key) {
         case _nameKey:
           hasName = true;
           name = checkType<String>(value, _nameKey);
           break;
         case _rootUriKey:
           hasRoot = true;
           rootUri = checkType<String>(value, _rootUriKey, name);
           break;
         case _packageUriKey:
           packageUri = checkType<String>(value, _packageUriKey, name);
           break;
         case _languageVersionKey:
           hasVersion = true;
           languageVersion = checkType<String>(value, _languageVersionKey, name);
           break;
         default:
           (extraData ??= {})[key] = value;
           break;
       }
     });
     if (!hasName) {
       onError(PackageConfigFormatException("Missing name entry", entry));
     }
     if (!hasRoot) {
       onError(PackageConfigFormatException("Missing rootUri entry", entry));
     }
     if (name == null || rootUri == null) return null;
     Uri root = baseLocation.resolve(rootUri);
     if (!root.path.endsWith("/")) root = root.replace(path: root.path + "/");
     Uri packageRoot = root;
     if (packageUri != null) packageRoot = root.resolve(packageUri);
     if (!packageRoot.path.endsWith("/")) {
       packageRoot = packageRoot.replace(path: packageRoot.path + "/");
     }

     LanguageVersion /*?*/ version;
     if (languageVersion != null) {
       version = parseLanguageVersion(languageVersion, onError);
     } else if (hasVersion) {
       version = SimpleInvalidLanguageVersion("invalid");
     }

     return SimplePackage.validate(name, root, packageRoot, version, extraData,
         (error) {
       if (error is ArgumentError) {
         onError(
             PackageConfigFormatException(error.message, error.invalidValue));
       } else {
         onError(error);
       }
     });
   }

   var map = checkType<Map<String, dynamic>>(json, "value");
   if (map == null) return const SimplePackageConfig.empty();
   Map<String, dynamic> /*?*/ extraData = null;
   List<Package> /*?*/ packageList;
   int /*?*/ configVersion;
   map.forEach((key, value) {
     switch (key) {
       case _configVersionKey:
         configVersion = checkType<int>(value, _configVersionKey) ?? 2;
         break;
       case _packagesKey:
         var packageArray = checkType<List<dynamic>>(value, _packagesKey) ?? [];
         var packages = <Package>[];
         for (var package in packageArray) {
           var packageMap =
               checkType<Map<String, dynamic>>(package, "package entry");
           if (packageMap != null) {
             var entry = parsePackage(packageMap);
             if (entry != null) {
               packages.add(entry);
             }
           }
         }
         packageList = packages;
         break;
       default:
         (extraData ??= {})[key] = value;
         break;
     }
   });
   if (configVersion == null) {
     onError(PackageConfigFormatException("Missing configVersion entry", json));
     configVersion = 2;
   }
   if (packageList == null) {
     onError(PackageConfigFormatException("Missing packages list", json));
     packageList = [];
   }
   return SimplePackageConfig(configVersion, packageList, extraData, (error) {
     if (error is ArgumentError) {
       onError(PackageConfigFormatException(error.message, error.invalidValue));
     } else {
       onError(error);
     }
   });
 }

 Future<void> writePackageConfigJson(
     PackageConfig config, Directory targetDirectory) async {
   // Write .dart_tool/package_config.json first.
   var file =
       File(pathJoin(targetDirectory.path, ".dart_tool", "package_config.json"));
   var baseUri = file.uri;
   var extraData = config.extraData;
   var data = <String, dynamic>{
     _configVersionKey: PackageConfig.maxVersion,
     _packagesKey: [
       for (var package in config.packages)
         <String, dynamic>{
           _nameKey: package.name,
           _rootUriKey: relativizeUri(package.root, baseUri),
           if (package.root != package.packageUriRoot)
             _packageUriKey: relativizeUri(package.packageUriRoot, package.root),
           if (package.languageVersion != null &&
               package.languageVersion is! InvalidLanguageVersion)
             _languageVersionKey: package.languageVersion.toString(),
           ...?_extractExtraData(package.extraData, _packageNames),
         }
     ],
     ...?_extractExtraData(config.extraData, _topNames),
   };

   // Write .packages too.
   String /*?*/ comment;
   if (extraData != null) {
     String /*?*/ generator = extraData[_generatorKey];
     if (generator != null) {
       String /*?*/ generated = extraData[_generatedKey];
       String /*?*/ generatorVersion = extraData[_generatorVersionKey];
       comment = "Generated by $generator"
           "${generatorVersion != null ? " $generatorVersion" : ""}"
           "${generated != null ? " on $generated" : ""}.";
     }
   }
   file = File(pathJoin(targetDirectory.path, ".packages"));
   baseUri = file.uri;
   var buffer = StringBuffer();
   packages_file.write(buffer, config, baseUri: baseUri, comment: comment);

   await Future.wait([
     file.writeAsString(JsonEncoder.withIndent("  ").convert(data)),
     file.writeAsString(buffer.toString()),
   ]);
 }

 /// If "extraData" is a JSON map, then return it, otherwise return null.
 ///
 /// If the value contains any of the [reservedNames] for the current context,
 /// entries with that name in the extra data are dropped.
 Map<String, dynamic> /*?*/ _extractExtraData(
     dynamic data, Iterable<String> reservedNames) {
   if (data is Map<String, dynamic>) {
     if (data.isEmpty) return null;
     for (var name in reservedNames) {
       if (data.containsKey(name)) {
         data = {
           for (var key in data.keys)
             if (!reservedNames.contains(key)) key: data[key]
         };
         if (data.isEmpty) return null;
         for (var value in data.values) {
           if (!_validateJson(value)) return null;
         }
       }
     }
     return data;
   }
   return null;
 }

 /// Checks that the object is a valid JSON-like data structure.
 bool _validateJson(dynamic object) {
   if (object == null || true == object || false == object) return true;
   if (object is num || object is String) return true;
   if (object is List<dynamic>) {
     for (var element in object) if (!_validateJson(element)) return false;
     return true;
   }
   if (object is Map<String, dynamic>) {
     for (var value in object.values) if (!_validateJson(value)) return false;
     return true;
   }
   return false;
 }
	// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	import "dart:convert";
	import "dart:io";
	import "dart:typed_data";

	import "discovery.dart" show packageConfigJsonPath;
	import "errors.dart";
	import "package_config_impl.dart";
	import "packages_file.dart" as packages_file;
	import "util.dart";

	const String _configVersionKey = "configVersion";
	const String _packagesKey = "packages";
	const List<String> _topNames = [_configVersionKey, _packagesKey];
	const String _nameKey = "name";
	const String _rootUriKey = "rootUri";
	const String _packageUriKey = "packageUri";
	const String _languageVersionKey = "languageVersion";
	const List<String> _packageNames = [
	_nameKey,
	_rootUriKey,
	_packageUriKey,
	_languageVersionKey
	];

	const String _generatedKey = "generated";
	const String _generatorKey = "generator";
	const String _generatorVersionKey = "generatorVersion";

	/// Reads a package configuration file.
	///
	/// Detects whether the [file] is a version one `.packages` file or
	/// a version two `package_config.json` file.
	///
	/// If the [file] is a `.packages` file and [preferNewest] is true,
	/// first checks whether there is an adjacent `.dart_tool/package_config.json`
	/// file, and if so, reads that instead.
	/// If [preferNewset] is false, the specified file is loaded even if it is
	/// a `.packages` file and there is an available `package_config.json` file.
	///
	/// The file must exist and be a normal file.
	Future<PackageConfig> readAnyConfigFile(
	File file, bool preferNewest, void onError(Object error)) async {
	Uint8List bytes;
	try {
	bytes = await file.readAsBytes();
	} catch (e) {
	onError(e);
	return const SimplePackageConfig.empty();
	}
	int firstChar = firstNonWhitespaceChar(bytes);
	if (firstChar != $lbrace) {
	// Definitely not a JSON object, probably a .packages.
	if (preferNewest) {
	var alternateFile = File(
	pathJoin(dirName(file.path), ".dart_tool", "package_config.json"));
	if (alternateFile.existsSync()) {
	Uint8List /?/ bytes;
	try {
	bytes = await alternateFile.readAsBytes();
	} catch (e) {
	onError(e);
	return const SimplePackageConfig.empty();
	}
	if (bytes != null) {
	return parsePackageConfigBytes(bytes, alternateFile.uri, onError);
	}
	}
	}
	return packages_file.parse(bytes, file.uri, onError);
	}
	return parsePackageConfigBytes(bytes, file.uri, onError);
	}

	/// Like [readAnyConfigFile] but uses a URI and an optional loader.
	Future<PackageConfig> readAnyConfigFileUri(
	Uri file,
	Future<Uint8List /?/ > loader(Uri uri) /?/,
	void onError(Object error),
	bool preferNewest) async {
	if (file.isScheme("package")) {
	throw PackageConfigArgumentError(
	file, "file", "Must not be a package: URI");
	}
	if (loader == null) {
	if (file.isScheme("file")) {
	return readAnyConfigFile(File.fromUri(file), preferNewest, onError);
	}
	loader = defaultLoader;
	}
	Uint8List bytes;
	try {
	bytes = await loader(file);
	} catch (e) {
	onError(e);
	return const SimplePackageConfig.empty();
	}
	if (bytes == null) {
	onError(PackageConfigArgumentError(
	file.toString(), "file", "File cannot be read"));
	return const SimplePackageConfig.empty();
	}
	int firstChar = firstNonWhitespaceChar(bytes);
	if (firstChar != $lbrace) {
	// Definitely not a JSON object, probably a .packages.
	if (preferNewest) {
	// Check if there is a package_config.json file.
	var alternateFile = file.resolveUri(packageConfigJsonPath);
	Uint8List alternateBytes;
	try {
	alternateBytes = await loader(alternateFile);
	} catch (e) {
	onError(e);
	return const SimplePackageConfig.empty();
	}
	if (alternateBytes != null) {
	return parsePackageConfigBytes(alternateBytes, alternateFile, onError);
	}
	}
	return packages_file.parse(bytes, file, onError);
	}
	return parsePackageConfigBytes(bytes, file, onError);
	}

	Future<PackageConfig> readPackageConfigJsonFile(
	File file, void onError(Object error)) async {
	Uint8List bytes;
	try {
	bytes = await file.readAsBytes();
	} catch (error) {
	onError(error);
	return const SimplePackageConfig.empty();
	}
	return parsePackageConfigBytes(bytes, file.uri, onError);
	}

	Future<PackageConfig> readDotPackagesFile(
	File file, void onError(Object error)) async {
	Uint8List bytes;
	try {
	bytes = await file.readAsBytes();
	} catch (error) {
	onError(error);
	return const SimplePackageConfig.empty();
	}
	return packages_file.parse(bytes, file.uri, onError);
	}

	final _jsonUtf8Decoder = json.fuse(utf8).decoder;

	PackageConfig parsePackageConfigBytes(
	Uint8List bytes, Uri file, void onError(Object error)) {
	// TODO(lrn): Make this simpler. Maybe parse directly from bytes.
	var jsonObject;
	try {
	jsonObject = _jsonUtf8Decoder.convert(bytes);
	} on FormatException catch (e) {
	onError(PackageConfigFormatException(e.message, e.source, e.offset));
	return const SimplePackageConfig.empty();
	}
	return parsePackageConfigJson(jsonObject, file, onError);
	}

	/// Creates a [PackageConfig] from a parsed JSON-like object structure.
	///
	/// The [json] argument must be a JSON object (`Map<String, dynamic>`)
	/// containing a `"configVersion"` entry with an integer value in the range
	/// 1 to [PackageConfig.maxVersion],
	/// and with a `"packages"` entry which is a JSON array (`List<dynamic>`)
	/// containing JSON objects which each has the following properties:
	///
	/// * `"name"`: The package name as a string.
	/// * `"rootUri"`: The root of the package as a URI stored as a string.
	/// * `"packageUri"`: Optionally the root of for `package:` URI resolution
	/// for the package, as a relative URI below the root URI
	/// stored as a string.
	/// * `"languageVersion"`: Optionally a language version string which is a
	/// an integer numeral, a decimal point (`.`) and another integer numeral,
	/// where the integer numeral cannot have a sign, and can only have a
	/// leading zero if the entire numeral is a single zero.
	///
	/// All other properties are stored in [extraData].
	///
	/// The [baseLocation] is used as base URI to resolve the "rootUri"
	/// URI referencestring.
	PackageConfig parsePackageConfigJson(
	dynamic json, Uri baseLocation, void onError(Object error)) {
	if (!baseLocation.hasScheme \|\| baseLocation.isScheme("package")) {
	throw PackageConfigArgumentError(baseLocation.toString(), "baseLocation",
	"Must be an absolute non-package: URI");
	}

	if (!baseLocation.path.endsWith("/")) {
	baseLocation = baseLocation.resolveUri(Uri(path: "."));
	}

	String typeName<T>() {
	if (0 is T) return "int";
	if ("" is T) return "string";
	if (const [] is T) return "array";
	return "object";
	}

	T checkType<T>(dynamic value, String name, [String /?/ packageName]) {
	if (value is T) return value;
	// The only types we are called with are [int], [String], [List<dynamic>]
	// and Map<String, dynamic>. Recognize which to give a better error message.
	var message =
	"$name${packageName != null ? " of package $packageName" : ""}"
	" is not a JSON ${typeName<T>()}";
	onError(PackageConfigFormatException(message, value));
	return null;
	}

	Package /?/ parsePackage(Map<String, dynamic> entry) {
	String /?/ name;
	String /?/ rootUri;
	String /?/ packageUri;
	String /?/ languageVersion;
	Map<String, dynamic> /?/ extraData;
	bool hasName = false;
	bool hasRoot = false;
	bool hasVersion = false;
	entry.forEach((key, value) {
	switch (key) {
	case _nameKey:
	hasName = true;
	name = checkType<String>(value, _nameKey);
	break;
	case _rootUriKey:
	hasRoot = true;
	rootUri = checkType<String>(value, _rootUriKey, name);
	break;
	case _packageUriKey:
	packageUri = checkType<String>(value, _packageUriKey, name);
	break;
	case _languageVersionKey:
	hasVersion = true;
	languageVersion = checkType<String>(value, _languageVersionKey, name);
	break;
	default:
	(extraData ??= {})[key] = value;
	break;
	}
	});
	if (!hasName) {
	onError(PackageConfigFormatException("Missing name entry", entry));
	}
	if (!hasRoot) {
	onError(PackageConfigFormatException("Missing rootUri entry", entry));
	}
	if (name == null \|\| rootUri == null) return null;
	Uri root = baseLocation.resolve(rootUri);
	if (!root.path.endsWith("/")) root = root.replace(path: root.path + "/");
	Uri packageRoot = root;
	if (packageUri != null) packageRoot = root.resolve(packageUri);
	if (!packageRoot.path.endsWith("/")) {
	packageRoot = packageRoot.replace(path: packageRoot.path + "/");
	}

	LanguageVersion /?/ version;
	if (languageVersion != null) {
	version = parseLanguageVersion(languageVersion, onError);
	} else if (hasVersion) {
	version = SimpleInvalidLanguageVersion("invalid");
	}

	return SimplePackage.validate(name, root, packageRoot, version, extraData,
	(error) {
	if (error is ArgumentError) {
	onError(
	PackageConfigFormatException(error.message, error.invalidValue));
	} else {
	onError(error);
	}
	});
	}

	var map = checkType<Map<String, dynamic>>(json, "value");
	if (map == null) return const SimplePackageConfig.empty();
	Map<String, dynamic> /?/ extraData = null;
	List<Package> /?/ packageList;
	int /?/ configVersion;
	map.forEach((key, value) {
	switch (key) {
	case _configVersionKey:
	configVersion = checkType<int>(value, _configVersionKey) ?? 2;
	break;
	case _packagesKey:
	var packageArray = checkType<List<dynamic>>(value, _packagesKey) ?? [];
	var packages = <Package>[];
	for (var package in packageArray) {
	var packageMap =
	checkType<Map<String, dynamic>>(package, "package entry");
	if (packageMap != null) {
	var entry = parsePackage(packageMap);
	if (entry != null) {
	packages.add(entry);
	}
	}
	}
	packageList = packages;
	break;
	default:
	(extraData ??= {})[key] = value;
	break;
	}
	});
	if (configVersion == null) {
	onError(PackageConfigFormatException("Missing configVersion entry", json));
	configVersion = 2;
	}
	if (packageList == null) {
	onError(PackageConfigFormatException("Missing packages list", json));
	packageList = [];
	}
	return SimplePackageConfig(configVersion, packageList, extraData, (error) {
	if (error is ArgumentError) {
	onError(PackageConfigFormatException(error.message, error.invalidValue));
	} else {
	onError(error);
	}
	});
	}

	Future<void> writePackageConfigJson(
	PackageConfig config, Directory targetDirectory) async {
	// Write .dart_tool/package_config.json first.
	var file =
	File(pathJoin(targetDirectory.path, ".dart_tool", "package_config.json"));
	var baseUri = file.uri;
	var extraData = config.extraData;
	var data = <String, dynamic>{
	_configVersionKey: PackageConfig.maxVersion,
	_packagesKey: [
	for (var package in config.packages)
	<String, dynamic>{
	_nameKey: package.name,
	_rootUriKey: relativizeUri(package.root, baseUri),
	if (package.root != package.packageUriRoot)
	_packageUriKey: relativizeUri(package.packageUriRoot, package.root),
	if (package.languageVersion != null &&
	package.languageVersion is! InvalidLanguageVersion)
	_languageVersionKey: package.languageVersion.toString(),
	...?_extractExtraData(package.extraData, _packageNames),
	}
	],
	...?_extractExtraData(config.extraData, _topNames),
	};

	// Write .packages too.
	String /?/ comment;
	if (extraData != null) {
	String /?/ generator = extraData[_generatorKey];
	if (generator != null) {
	String /?/ generated = extraData[_generatedKey];
	String /?/ generatorVersion = extraData[_generatorVersionKey];
	comment = "Generated by $generator"
	"${generatorVersion != null ? " $generatorVersion" : ""}"
	"${generated != null ? " on $generated" : ""}.";
	}
	}
	file = File(pathJoin(targetDirectory.path, ".packages"));
	baseUri = file.uri;
	var buffer = StringBuffer();
	packages_file.write(buffer, config, baseUri: baseUri, comment: comment);

	await Future.wait([
	file.writeAsString(JsonEncoder.withIndent(" ").convert(data)),
	file.writeAsString(buffer.toString()),
	]);
	}

	/// If "extraData" is a JSON map, then return it, otherwise return null.
	///
	/// If the value contains any of the [reservedNames] for the current context,
	/// entries with that name in the extra data are dropped.
	Map<String, dynamic> /?/ _extractExtraData(
	dynamic data, Iterable<String> reservedNames) {
	if (data is Map<String, dynamic>) {
	if (data.isEmpty) return null;
	for (var name in reservedNames) {
	if (data.containsKey(name)) {
	data = {
	for (var key in data.keys)
	if (!reservedNames.contains(key)) key: data[key]
	};
	if (data.isEmpty) return null;
	for (var value in data.values) {
	if (!_validateJson(value)) return null;
	}
	}
	}
	return data;
	}
	return null;
	}

	/// Checks that the object is a valid JSON-like data structure.
	bool _validateJson(dynamic object) {
	if (object == null \|\| true == object \|\| false == object) return true;
	if (object is num \|\| object is String) return true;
	if (object is List<dynamic>) {
	for (var element in object) if (!_validateJson(element)) return false;
	return true;
	}
	if (object is Map<String, dynamic>) {
	for (var value in object.values) if (!_validateJson(value)) return false;
	return true;
	}
	return false;
	}