Support for web platform and export class Parser

CHANGELOG.md

@@ -6,6 +6,13 @@ This project follows [pub-flavored semantic versioning][pub-semver]. ([more][pub
 [pub-semver]: https://www.dartlang.org/tools/pub/versioning.html#semantic-versions
 [pub-semver-readme]: https://pub.dartlang.org/packages/pub_semver
 
+## 4.3.0
+
+- [feat] Moved `lib/src/dotenv.dart` and `lib/src/parser.dart` into `lib/` and deleted the empty `lib/src` directory. With this change, the user can now import the `Parser` class without importing files from the `lib/src` directory, because that is considered a bad practice. [See lint implementation_imports](https://dart.dev/tools/linter-rules/implementation_imports)
+- [deps] added package `universal_io`
+- [fix] typo, renamed `Parser._singleQuot` to `Parser._singleQuote` 
+- [fix] replaced dependencies of `dart:io` in `lib/dotenv.dart` and `lib/parser.dart` with `package:universal_io/io.dart`, this should make the package compatible with flutter web and fix [#33][]
+
 ## 4.2.0
 
 - [feat] add optional parameter `quiet` to `DotEnv` constructor
@@ -102,3 +109,4 @@ Initial release.
 [#16]: https://github.com/mockturtl/dotenv/issues/16
 [#21]: https://github.com/mockturtl/dotenv/pull/21
 [#27]: https://github.com/mockturtl/dotenv/pull/27
+[#33]: https://github.com/mockturtl/dotenv/issues/33

example/example.dart

@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:dotenv/dotenv.dart';
 
 void main() {
@@ -19,4 +17,4 @@ void main() {
   p('your home directory is still: ${env['HOME']}');
 }
 
-p(String msg) => stdout.writeln(msg);
+p(String msg) => print(msg);

lib/dotenv.dart

@@ -1,3 +1,12 @@
+import 'package:meta/meta.dart';
+import 'package:universal_io/io.dart';
+
+import 'parser.dart';
+
+/// Loads key-value pairs from a file into a [Map<String, String>].
+///
+/// The parser will attempt to handle simple variable substitution,
+/// respect single- vs. double-quotes, and ignore `#comments` or the `export` keyword.
 /// Loads environment variables from a `.env` file.
 ///
 /// ## usage
@@ -19,4 +28,82 @@
 ///
 ///     const _requiredEnvVars = ['host', 'port'];
 ///     bool get hasEnv => env.isEveryDefined(_requiredEnvVars);
-export 'package:dotenv/src/dotenv.dart';
+class DotEnv {
+  /// If true, the underlying map will contain the entries of [Platform.environment],
+  /// even after calling [clear].
+  /// Otherwise, it will be empty until populated by [load].
+  final bool includePlatformEnvironment;
+
+  /// If true, suppress "file not found" messages on [stderr] during [load].
+  final bool quiet;
+
+  final _map = <String, String>{};
+
+  DotEnv({this.includePlatformEnvironment = false, this.quiet = false}) {
+    if (includePlatformEnvironment) _addPlatformEnvironment();
+  }
+
+  /// Provides access to the underlying [Map].
+  ///
+  /// Prefer using [operator[]] to read values.
+  @visibleForTesting
+  Map<String, String> get map => _map;
+
+  /// Reads the value for [key] from the underlying map.
+  ///
+  /// Returns `null` if [key] is absent.  See [isDefined].
+  String? operator [](String key) => _map[key];
+
+  /// Calls [Map.addAll] on the underlying map.
+  void addAll(Map<String, String> other) => _map.addAll(other);
+
+  /// Calls [Map.clear] on the underlying map.
+  ///
+  /// If [includePlatformEnvironment] is true, the entries of [Platform.environment] will be reinserted.
+  void clear() {
+    _map.clear();
+    if (includePlatformEnvironment) _addPlatformEnvironment();
+  }
+
+  /// Equivalent to [operator []] when the underlying map contains [key],
+  /// and the value is non-empty.  See [isDefined].
+  ///
+  /// Otherwise, calls [orElse] and returns the value.
+  String getOrElse(String key, String Function() orElse) =>
+      isDefined(key) ? _map[key]! : orElse();
+
+  /// True if [key] has a nonempty value in the underlying map.
+  ///
+  /// Differs from [Map.containsKey] by excluding empty values.
+  bool isDefined(String key) => _map[key]?.isNotEmpty ?? false;
+
+  /// True if all supplied [vars] have nonempty value; false otherwise.
+  ///
+  /// See [isDefined].
+  bool isEveryDefined(Iterable<String> vars) => vars.every(isDefined);
+
+  /// Parses environment variables from each path in [filenames], and adds them
+  /// to the underlying [Map].
+  ///
+  /// Logs to [stderr] if any file does not exist; see [quiet].
+  void load([
+    Iterable<String> filenames = const ['.env'],
+    Parser psr = const Parser(),
+  ]) {
+    for (var filename in filenames) {
+      var f = File.fromUri(Uri.file(filename));
+      var lines = _verify(f);
+      _map.addAll(psr.parse(lines));
+    }
+  }
+
+  void _addPlatformEnvironment() => _map.addAll(Platform.environment);
+
+  List<String> _verify(File f) {
+    if (!f.existsSync()) {
+      if (!quiet) stderr.writeln('[dotenv] Load failed: file not found: $f');
+      return [];
+    }
+    return f.readAsLinesSync();
+  }
+}

lib/src/parser.dart → lib/parser.dart

@@ -1,11 +1,10 @@
-import 'dart:io';
-
 import 'package:meta/meta.dart';
+import 'package:universal_io/io.dart';
 
 /// Creates key-value pairs from strings formatted as environment
 /// variable definitions.
 class Parser {
-  static const _singleQuot = "'";
+  static const _singleQuote = "'";
   static const _keyword = 'export';
 
   static final _comment = new RegExp(r'''#.*(?:[^'"])$''');
@@ -49,10 +48,10 @@ class Parser {
     if (k.isEmpty) return {};
 
     var rhs = stripped.substring(idx + 1, stripped.length).trim();
-    var quotChar = surroundingQuote(rhs);
+    var quoteChar = surroundingQuote(rhs);
     var v = unquote(rhs);
 
-    if (quotChar == _singleQuot) // skip substitution in single-quoted values
+    if (quoteChar == _singleQuote) // skip substitution in single-quoted values
       return {k: v};
 
     return {k: interpolate(v, env)};

pubspec.yaml

@@ -1,5 +1,5 @@
 name: dotenv
-version: 4.2.0
+version: 4.3.0
 
 description: Load environment variables from a `.env` file.
 homepage: https://github.com/mockturtl/dotenv
@@ -9,6 +9,7 @@ environment:
 dependencies:
   args: ^2.3.0
   meta: ^1.7.0
+  universal_io: ^2.2.2
 
 dev_dependencies:
   tidy: ^3.1.0

test/dotenv_test.dart

@@ -1,5 +1,5 @@
 import 'package:collection/collection.dart' show MapEquality;
-import 'package:dotenv/src/dotenv.dart';
+import 'package:dotenv/dotenv.dart';
 import 'package:test/test.dart';
 
 void main() {

test/parser_test.dart

@@ -1,7 +1,7 @@
 import 'dart:io';
 import 'dart:math';
 
-import 'package:dotenv/src/parser.dart';
+import 'package:dotenv/parser.dart';
 import 'package:test/test.dart';
 
 void main() {