[cli_config] First version (#45)

pkgs/cli_config/analysis_options.yaml

@@ -1,4 +1,4 @@
-include: package:lints/recommended.yaml
+include: package:dart_flutter_team_lints/analysis_options.yaml
 
 analyzer:
   language:

pkgs/cli_config/example/bin/cli_config_example.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2023, 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 'package:cli_config/cli_config.dart';
+
+Future<void> main(List<String> args) async {
+  final config = await Config.fromArgs(args: args);
+  final myPath =
+      config.optionalPath('my_path', resolveUri: true, mustExist: false);
+  print(myPath?.path);
+}

pkgs/cli_config/example/pubspec.yaml

@@ -0,0 +1,13 @@
+name: cli_config_example
+description: An example for cli_config.
+
+repository: https://github.com/dart-lang/tools/tree/main/pkgs/cli_config/example
+
+publish_to: none
+
+environment:
+  sdk: ">=2.19.3 <4.0.0"
+
+dependencies:
+  cli_config:
+    path: ../

pkgs/cli_config/lib/cli_config.dart

@@ -6,4 +6,4 @@
 /// and environment variables.
 library cli_config;
 
-export 'src/cli_config.dart';
+export 'src/config.dart';

pkgs/cli_config/lib/src/cli_parser.dart

@@ -0,0 +1,53 @@
+// Copyright (c) 2023, 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 'package:args/args.dart';
+
+class CliParser {
+  final ArgParser parser = () {
+    final parser = ArgParser();
+    parser.addFlag(
+      'help',
+      abbr: 'h',
+      help: 'Show this help.',
+    );
+    parser.addMultiOption(
+      'define',
+      abbr: 'D',
+      help: '''Define or override a config property from command line.
+The same option can be passed multiple times.
+Keys should only contain lower-case alphanumeric characters, underscores,
+and '.'s''',
+    );
+    parser.addOption(
+      'config',
+      abbr: 'c',
+      help: '''Path to JSON or YAML config file.
+Keys should only contain lower-case alphanumeric characters, and underscores.
+Hierarchies should be maps.''',
+    );
+    return parser;
+  }();
+
+  ArgResults parse(List<String> args) => parser.parse(args);
+}
+
+class DefinesParser {
+  static final _defineRegex = RegExp('([a-z_.]+)=(.+)');
+
+  Map<String, List<String>> parse(List<String> args) {
+    final defines = <String, List<String>>{};
+    for (final arg in args) {
+      final match = _defineRegex.matchAsPrefix(arg);
+      if (match == null || match.group(0) != arg) {
+        throw FormatException("Define '$arg' does not match expected pattern "
+            "'${_defineRegex.pattern}'.");
+      }
+      final key = match.group(1)!;
+      final value = match.group(2)!;
+      defines[key] = (defines[key] ?? [])..add(value);
+    }
+    return defines;
+  }
+}

pkgs/cli_config/lib/src/cli_source.dart

@@ -0,0 +1,95 @@
+// Copyright (c) 2023, 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 'config.dart';
+import 'source.dart';
+
+class CliSource extends Source {
+  /// Configuration options passed in via CLI arguments.
+  ///
+  /// Options can be passed multiple times, so the values here are a list.
+  ///
+  /// Stored as a flat non-hierarchical structure, keys contain `.`.
+  final Map<String, List<String>> _cli;
+
+  /// If provided, used to resolve paths within [_cli].
+  ///
+  /// Typically the current working directory at application start.
+  @override
+  final Uri? baseUri;
+
+  CliSource(this._cli, this.baseUri);
+
+  @override
+  String? optionalString(String key) {
+    final value = _cli[key];
+    if (value == null) {
+      return null;
+    }
+    if (value.length > 1) {
+      throw FormatException(
+          "More than one value was passed for '$key' in the CLI defines."
+          ' Values passed: $value');
+    }
+    return value.single;
+  }
+
+  @override
+  List<String>? stringList(
+    String key, {
+    String? splitPattern,
+  }) {
+    final cliValue = _cli[key];
+    if (cliValue == null) {
+      return null;
+    }
+    if (splitPattern != null) {
+      return [for (final value in cliValue) ...value.split(splitPattern)];
+    }
+    return cliValue;
+  }
+
+  @override
+  bool? optionalBool(String key) {
+    final stringValue = optionalString(key);
+    if (stringValue != null) {
+      Source.throwIfUnexpectedValue(key, stringValue, Config.boolStrings.keys);
+      return Config.boolStrings[stringValue]!;
+    }
+    return null;
+  }
+
+  @override
+  int? optionalInt(String key) {
+    final stringValue = optionalString(key);
+    if (stringValue != null) {
+      try {
+        return int.parse(stringValue);
+      } on FormatException catch (e) {
+        throw FormatException(
+            "Unexpected value '$stringValue' for key '$key'. Expected an int."
+            ' ${e.message}');
+      }
+    }
+    return null;
+  }
+
+  @override
+  double? optionalDouble(String key) {
+    final stringValue = optionalString(key);
+    if (stringValue != null) {
+      try {
+        return double.parse(stringValue);
+      } on FormatException catch (e) {
+        throw FormatException(
+            "Unexpected value '$stringValue' for key '$key'. Expected a double."
+            ' ${e.message}');
+      }
+    }
+    return null;
+  }
+
+  @override
+  String toString() => 'CliSource($_cli)';
+}