[cli_config] Support non-String map keys (#73)

pkgs/cli_config/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.1.1
+
+- Support non-String map keys in YAML configuration files.
+- Support null values in YAML configuration files.
+
 ## 0.1.0
 
 - Initial version.

pkgs/cli_config/lib/src/config.dart

@@ -103,7 +103,7 @@ class Config {
     Uri? fileSourceUri,
   }) {
     // Parse config file.
-    final fileConfig = FileParser().parseMap(fileParsed);
+    final fileConfig = FileParser().parseToplevelMap(fileParsed);
 
     // Parse CLI argument defines.
     final cliConfig = DefinesParser().parse(commandLineDefines);

pkgs/cli_config/lib/src/file_parser.dart

@@ -5,7 +5,7 @@
 import 'package:yaml/yaml.dart';
 
 class FileParser {
-  Map<String, dynamic> parse(
+  Map<String, Object?> parse(
     String fileContents, {
     Uri? sourceUrl,
   }) {
@@ -16,24 +16,25 @@ class FileParser {
     if (parsedYaml is! Map) {
       throw FormatException('YAML config must be set of key value pairs.');
     }
-    return parseMap(parsedYaml);
+    return parseToplevelMap(parsedYaml);
   }
 
-  Map<String, Object> parseMap(Map<dynamic, dynamic> input) => {
-        for (final entry in input.entries)
-          parseKey(entry.key as String): parseValue(entry.value as Object),
-      };
-
-  Object parseValue(Object value) {
-    if (value is Map) {
-      return parseMap(value);
+  Map<String, Object?> parseToplevelMap(Map<dynamic, dynamic> input) {
+    final result = <String, Object?>{};
+    for (final entry in input.entries) {
+      final key = parseToplevelKey(entry.key);
+      final value = entry.value as Object?;
+      result[key] = value;
     }
-    return value;
+    return result;
   }
 
   static final _keyRegex = RegExp('([a-z-_]+)');
 
-  String parseKey(String key) {
+  String parseToplevelKey(Object? key) {
+    if (key is! String) {
+      throw FormatException("Key '$key' is not a String.");
+    }
     final match = _keyRegex.matchAsPrefix(key);
     if (match == null || match.group(0) != key) {
       throw FormatException("Define '$key' does not match expected pattern "

pkgs/cli_config/pubspec.yaml

@@ -1,6 +1,6 @@
 name: cli_config
 description: A library to take config values from configuration files, CLI arguments, and environment variables.
-version: 0.1.0
+version: 0.1.1
 
 repository: https://github.com/dart-lang/tools/tree/main/pkgs/cli_config
 

pkgs/cli_config/test/cli_config_test.dart

@@ -371,11 +371,20 @@ void main() {
     expect(() => Config.fromConfigFileContents(fileContents: "['asdf']"),
         throwsFormatException);
     expect(
-      () => Config.fromConfigFileContents(fileContents: '''foo:
-  bar:
-    WRONGKEY:
-      1
-'''),
+      () => Config.fromConfigFileContents(
+          fileContents: '''
+WRONGKEY:
+  1
+'''
+              .trim()),
+      throwsFormatException,
+    );
+    expect(
+      () => Config.fromConfigFileContents(
+          fileContents: '''
+1: 'asdf'
+'''
+              .trim()),
       throwsFormatException,
     );
   });
@@ -504,4 +513,46 @@ void main() {
       expect(config.pathList('my_list'), <String>[]);
     }
   });
+
+  test('non-string key maps', () {
+    // This is valid in YAML (not in JSON).
+    //
+    // Such values cannot be accessed with our hierarchical keys, but they can
+    // be accessed with [Config.valueOf].
+    final config = Config(
+      fileParsed: {
+        'my_non_string_key_map': {
+          1: 'asdf',
+          2: 'foo',
+        },
+      },
+    );
+
+    expect(
+      config.valueOf<Map<Object, Object?>>('my_non_string_key_map'),
+      {
+        1: 'asdf',
+        2: 'foo',
+      },
+    );
+  });
+
+  test('null values in maps', () {
+    final config = Config(
+      fileParsed: {
+        'my_non_string_key_map': {
+          'x': null,
+          'y': 42,
+        },
+      },
+    );
+
+    expect(
+      config.valueOf<Map<Object, Object?>>('my_non_string_key_map'),
+      {
+        'x': null,
+        'y': 42,
+      },
+    );
+  });
 }