Implement deserialization of dictionaries using primitives as keys

Tomlet.Tests/DictionaryTests.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Tomlet.Models;
 using Tomlet.Tests.TestModelClasses;
 using Xunit;
@@ -53,4 +54,40 @@ public void DictionaryKeysShouldBeProperlyEscaped()
             Assert.Contains(expectedValue, serialized);
         }
     }
+
+    private bool PrimitiveKeyTestHelper<T>(params T[] values) where T : unmanaged, IConvertible
+    {
+        var primitiveDict = new Dictionary<T, string>();
+        for (int i=0; i<values.Length; i++) {
+            T val = values[i];
+            primitiveDict[val] = $"Test {i+1}";
+        }
+
+        var serialized = TomletMain.TomlStringFrom(primitiveDict);
+
+        var deserialized = TomletMain.To<Dictionary<T, string>>(serialized);
+
+        foreach (var (key, value) in primitiveDict) {
+            if (!deserialized.ContainsKey(key)) {
+                return false;
+            }
+            if (deserialized[key] != value) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    [Fact]
+    public void PrimitiveDictionaryKeysShouldWork()
+    {
+        Assert.True(PrimitiveKeyTestHelper(true, false));
+        Assert.True(PrimitiveKeyTestHelper(long.MaxValue, long.MinValue, 0, 4736251));
+        Assert.True(PrimitiveKeyTestHelper(uint.MinValue, uint.MaxValue, 0u, 1996u));
+
+        // \n causes an exception when deserializing
+        // I don't consider this a bug with the primitive dict deserializer because the string dict deserializer also has this issue
+        Assert.True(PrimitiveKeyTestHelper('a', 'b', 'c' /*, '\n' */));
+    }
+
 }

Tomlet/Extensions/ReflectionExtensions.cs

@@ -32,5 +32,22 @@ internal static bool TryGetBestMatchConstructor(this Type type, out ConstructorI
             bestMatchConstructor = parameterizedConstructors.Single();
             return true;
         }
+
+        internal static bool IsIntegerType(this Type type) {
+            switch (Type.GetTypeCode(type)) {
+                case TypeCode.Byte:
+                case TypeCode.SByte:
+                case TypeCode.UInt16:
+                case TypeCode.Int16:
+                case TypeCode.UInt32:
+                case TypeCode.Int32:
+                case TypeCode.UInt64:
+                case TypeCode.Int64:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
     }
 }

Tomlet/TomlSerializationMethods.cs

@@ -1,17 +1,20 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Reflection;
 using Tomlet.Attributes;
 using Tomlet.Exceptions;
+using Tomlet.Extensions;
 using Tomlet.Models;
 
 namespace Tomlet
 {
     public static class TomlSerializationMethods
     {
         private static MethodInfo _stringKeyedDictionaryMethod = typeof(TomlSerializationMethods).GetMethod(nameof(StringKeyedDictionaryDeserializerFor), BindingFlags.Static | BindingFlags.NonPublic)!;
+        private static MethodInfo _primitiveKeyedDictionaryMethod = typeof(TomlSerializationMethods).GetMethod(nameof(PrimitiveKeyedDictionaryDeserializerFor), BindingFlags.Static | BindingFlags.NonPublic)!;
         private static MethodInfo _genericDictionarySerializerMethod = typeof(TomlSerializationMethods).GetMethod(nameof(GenericDictionarySerializer), BindingFlags.Static | BindingFlags.NonPublic)!;
         private static MethodInfo _genericNullableSerializerMethod = typeof(TomlSerializationMethods).GetMethod(nameof(GenericNullableSerializer), BindingFlags.Static | BindingFlags.NonPublic)!;
 
@@ -195,6 +198,12 @@
                 {
                     return (Deserialize<object>)_stringKeyedDictionaryMethod.MakeGenericMethod(genericArgs[1]).Invoke(null, new object[]{options})!;
                 }
+
+                if (genericArgs[0].IsIntegerType() || genericArgs[0] == typeof(bool) || genericArgs[0] == typeof(char))
+                {
+                    // float primitives not supported due to decimal point causing issues
+                    return (Deserialize<object>)_primitiveKeyedDictionaryMethod.MakeGenericMethod(genericArgs).Invoke(null, new object[]{options})!;
+                }
             }
 
             return TomlCompositeDeserializer.For(t, options);
@@ -279,7 +288,24 @@
                 return table.Entries.ToDictionary(entry => entry.Key, entry => (T)deserializer(entry.Value));
             };
         }
-
+
+        // unmanaged + IConvertible is the closest I can get to expressing "primitives only"
+        private static Deserialize<Dictionary<TKey, TValue>> PrimitiveKeyedDictionaryDeserializerFor<TKey, TValue>(TomlSerializerOptions options) where TKey : unmanaged, IConvertible
+        {
+            var valueDeserializer = GetDeserializer(typeof(TValue), options);
+
+            return value =>
+            {
+                if (value is not TomlTable table)
+                    throw new TomlTypeMismatchException(typeof(TomlTable), value.GetType(), typeof(Dictionary<TKey, TValue>));
+
+                return table.Entries.ToDictionary(
+                    entry => (TKey)(entry.Key as IConvertible).ToType(typeof(TKey), CultureInfo.InvariantCulture),
+                    entry => (TValue)valueDeserializer(entry.Value)
+                );
+            };
+        }
+
         private static TomlValue? GenericNullableSerializer<T>(T? nullable, TomlSerializerOptions options) where T : struct
         {
             var elementSerializer = GetSerializer(typeof(T), options);
@@ -364,7 +390,7 @@
 
                 for (var i = 0; i < keys.Count; i++)
                 {
                     table.PutValue(keys[i], values[i], true);
                 }
 
                 return table;