feat: Add support for TomlFieldAttribute (#54) (#55)

Tomlet/Attributes/TomlFieldAttribute.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace Tomlet.Attributes;
+
+[AttributeUsage(AttributeTargets.Field)]
+public class TomlFieldAttribute : Attribute
+{
+    private readonly string _mapFrom;
+
+    public TomlFieldAttribute(string mapFrom)
+    {
+        _mapFrom = mapFrom;
+    }
+
+    public string GetMappedString()
+    {
+        return _mapFrom;
+    }
+}

Tomlet/TomlCompositeDeserializer.cs

@@ -52,7 +52,10 @@ public static TomlSerializationMethods.Deserialize<object> For(Type type, TomlSe
             var fields = type.GetFields(memberFlags);
 
             //Ignore NonSerialized and CompilerGenerated fields.
-            fields = fields.Where(f => !f.IsNotSerialized && GenericExtensions.GetCustomAttribute<CompilerGeneratedAttribute>(f) == null).ToArray();
+            var fieldsDict = fields
+                .Where(f => !f.IsNotSerialized && GenericExtensions.GetCustomAttribute<CompilerGeneratedAttribute>(f) == null)
+                .Select(f => new KeyValuePair<FieldInfo, TomlFieldAttribute?>(f, GenericExtensions.GetCustomAttribute<TomlFieldAttribute>(f)))
+                .ToDictionary(tuple => tuple.Key, tuple => tuple.Value);
 
             var props = type.GetProperties(memberFlags);
 
@@ -62,7 +65,7 @@ public static TomlSerializationMethods.Deserialize<object> For(Type type, TomlSe
                 .Select(p => new KeyValuePair<PropertyInfo, TomlPropertyAttribute?>(p, GenericExtensions.GetCustomAttribute<TomlPropertyAttribute>(p)))
                 .ToDictionary(tuple => tuple.Key, tuple => tuple.Value);
 
-            if (fields.Length + propsDict.Count == 0)
+            if (fieldsDict.Count + propsDict.Count == 0)
                 return value => CreateInstance(type, value, options, out _);
 
             deserializer = value =>
@@ -72,12 +75,13 @@ public static TomlSerializationMethods.Deserialize<object> For(Type type, TomlSe
 
                 var instance = CreateInstance(type, value, options, out var assignedMembers);
 
-                foreach (var field in fields)
+                foreach (var (field, attribute) in fieldsDict)
                 {
-                    if (!options.OverrideConstructorValues && assignedMembers.Contains(field.Name))
+                    var name = attribute?.GetMappedString() ?? field.Name;
+                    if (!options.OverrideConstructorValues && assignedMembers.Contains(name))
                         continue;
 
-                    if (!table.TryGetValue(field.Name, out var entry))
+                    if (!table.TryGetValue(name, out var entry))
                         continue; //TODO: Do we want to make this configurable? As in, throw exception if data is missing?
 
                     object fieldValue;

Tomlet/TomlCompositeSerializer.cs

@@ -35,7 +35,7 @@ public static TomlSerializationMethods.Serialize<object> For(Type type, TomlSeri
 
             var fields = type.GetFields(memberFlags);
             var fieldAttribs = fields
-                .ToDictionary(f => f, f => new {inline = GenericExtensions.GetCustomAttribute<TomlInlineCommentAttribute>(f), preceding = GenericExtensions.GetCustomAttribute<TomlPrecedingCommentAttribute>(f), noInline = GenericExtensions.GetCustomAttribute<TomlDoNotInlineObjectAttribute>(f)});
+                .ToDictionary(f => f, f => new {inline = GenericExtensions.GetCustomAttribute<TomlInlineCommentAttribute>(f), preceding = GenericExtensions.GetCustomAttribute<TomlPrecedingCommentAttribute>(f), field = GenericExtensions.GetCustomAttribute<TomlFieldAttribute>(f), noInline = GenericExtensions.GetCustomAttribute<TomlDoNotInlineObjectAttribute>(f)});
             var props = type.GetProperties(memberFlags)
                 .ToArray();
             var propAttribs = props
@@ -73,21 +73,21 @@ public static TomlSerializationMethods.Serialize<object> For(Type type, TomlSeri
                     if(tomlValue == null)
                         continue;
 
-                    var commentAttribs = fieldAttribs[field];
+                    var thisFieldAttribs = fieldAttribs[field];
 
                     if (resultTable.ContainsKey(field.Name))
                         //Do not overwrite fields if they have the same name as something already in the table
                         //This fixes serializing types which re-declare a field using the `new` keyword, overwriting a field of the same name
                         //in its supertype. 
                         continue;
 
-                    tomlValue.Comments.InlineComment = commentAttribs.inline?.Comment;
-                    tomlValue.Comments.PrecedingComment = commentAttribs.preceding?.Comment;
+                    tomlValue.Comments.InlineComment = thisFieldAttribs.inline?.Comment;
+                    tomlValue.Comments.PrecedingComment = thisFieldAttribs.preceding?.Comment;
 
-                    if(commentAttribs.noInline != null && tomlValue is TomlTable table)
+                    if(thisFieldAttribs.noInline != null && tomlValue is TomlTable table)
                         table.ForceNoInline = true;
 
-                    resultTable.PutValue(field.Name, tomlValue);
+                    resultTable.PutValue(thisFieldAttribs.field?.GetMappedString() ?? field.Name, tomlValue);
                 }
 
                 foreach (var prop in props)