Merge pull request #51 from chickensoft-games/fix/map-readonly

fix: implement read only dictionary from map

Chickensoft.Collections.Tests/src/MapTest.cs

@@ -145,9 +145,12 @@ public void KeysAreOrdered() {
       ["a"] = 1,
     };
 
+    var readonlyMap = map as IReadOnlyDictionary<string, int>;
+
     map["b"] = 3;
 
     map.Keys.ShouldBe(["b", "a"]);
+    readonlyMap.Keys.ShouldBe(["b", "a"]);
   }
 
   [Fact]
@@ -170,12 +173,23 @@ public void Values() {
       ["a"] = 1,
       ["b"] = 2
     };
+
+    var readonlyMap = map as IReadOnlyDictionary<string, int>;
+
     var values = map.Values.ToList();
 
     values.ShouldBeAssignableTo<ICollection<int>>();
 
     values[0].ShouldBe(1);
     values[1].ShouldBe(2);
+
+
+    values = readonlyMap.Values.ToList();
+
+    values.ShouldBeAssignableTo<ICollection<int>>();
+
+    values[0].ShouldBe(1);
+    values[1].ShouldBe(2);
   }
 
   [Fact]

Chickensoft.Collections/src/collections/Map.cs

@@ -12,7 +12,9 @@ namespace Chickensoft.Collections;
 /// <typeparam name="TKey">Key type.</typeparam>
 /// <typeparam name="TValue">Value type.</typeparam>
 public class Map<TKey, TValue> :
-  IDictionary<TKey, TValue> where TKey : notnull {
+  IDictionary<TKey, TValue>,
+  IReadOnlyDictionary<TKey, TValue>
+  where TKey : notnull {
 
   private readonly OrderedDictionary _collection = [];
 
@@ -71,6 +73,14 @@ public Map(IEnumerable<KeyValuePair<TKey, TValue>> collection) {
   public ICollection<TValue> Values =>
     _collection.Values.Cast<TValue>().ToArray();
 
+  #region IReadOnlyDictionary<TKey, TValue>
+  IEnumerable<TKey> IReadOnlyDictionary<TKey, TValue>.Keys =>
+    _collection.Keys.Cast<TKey>();
+
+  IEnumerable<TValue> IReadOnlyDictionary<TKey, TValue>.Values =>
+    _collection.Values.Cast<TValue>();
+  #endregion IReadOnlyDictionary<TKey, TValue>
+
   /// <summary>Insert a key and value at the specified index.</summary>
   /// <param name="index">Index to insert to.</param>
   /// <param name="key">Key.</param>