Implemented command type readers, parser and service.

src/Discord.Net.Commands/Results/ExecuteResult.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Diagnostics;
+
+namespace Discord.Commands
+{
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public struct ExecuteResult : IResult
+    {
+        public Exception Exception { get; }
+
+        public CommandError? Error { get; }
+        public string ErrorReason { get; }
+
+        public bool IsSuccess => !Error.HasValue;
+
+        private ExecuteResult(Exception exception, CommandError? error, string errorReason)
+        {
+            Exception = exception;
+            Error = error;
+            ErrorReason = errorReason;
+        }
+
+        internal static ExecuteResult FromSuccess()
+            => new ExecuteResult(null, null, null);
+        internal static ExecuteResult FromError(CommandError error, string reason)
+            => new ExecuteResult(null, error, reason);
+        internal static ExecuteResult FromError(Exception ex)
+            => new ExecuteResult(ex, CommandError.Exception, ex.Message);
+        internal static ExecuteResult FromError(ParseResult result)
+            => new ExecuteResult(null, result.Error, result.ErrorReason);
+        
+        public override string ToString() => IsSuccess ? "Success" : $"{Error}: {ErrorReason}";
+        private string DebuggerDisplay => IsSuccess ? "Success" : $"{Error}: {ErrorReason}";
+    }
+}

src/Discord.Net.Commands/Results/IResult.cs

@@ -0,0 +1,9 @@
+namespace Discord.Commands
+{
+    public interface IResult
+    {
+        CommandError? Error { get; }
+        string ErrorReason { get; }
+        bool IsSuccess { get; }
+    }
+}

src/Discord.Net.Commands/Results/ParseResult.cs

@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace Discord.Commands
+{
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public struct ParseResult : IResult
+    {
+        public IReadOnlyList<object> Values { get; }
+
+        public CommandError? Error { get; }
+        public string ErrorReason { get; }
+
+        public bool IsSuccess => !Error.HasValue;
+
+        private ParseResult(IReadOnlyList<object> values, CommandError? error, string errorReason)
+        {
+            Values = values;
+            Error = error;
+            ErrorReason = errorReason;
+        }
+
+        internal static ParseResult FromSuccess(IReadOnlyList<object> values)
+            => new ParseResult(values, null, null);
+        internal static ParseResult FromError(CommandError error, string reason)
+            => new ParseResult(null, error, reason);
+        internal static ParseResult FromError(SearchResult result)
+            => new ParseResult(null, result.Error, result.ErrorReason);
+        internal static ParseResult FromError(TypeReaderResult result)
+            => new ParseResult(null, result.Error, result.ErrorReason);
+
+        public override string ToString() => IsSuccess ? "Success" : $"{Error}: {ErrorReason}";
+        private string DebuggerDisplay => IsSuccess ? $"Success ({Values.Count} Values)" : $"{Error}: {ErrorReason}";
+    }
+}

src/Discord.Net.Commands/Results/SearchResult.cs

@@ -0,0 +1,33 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace Discord.Commands
+{
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public struct SearchResult : IResult
+    {
+        public IReadOnlyList<Command> Commands { get; }
+        public string ArgText { get; }        
+
+        public CommandError? Error { get; }
+        public string ErrorReason { get; }
+
+        public bool IsSuccess => !Error.HasValue;
+
+        private SearchResult(IReadOnlyList<Command> commands, string argText, CommandError? error, string errorReason)
+        {
+            Commands = commands;
+            ArgText = argText;
+            Error = error;
+            ErrorReason = errorReason;
+        }
+
+        internal static SearchResult FromSuccess(IReadOnlyList<Command> commands, string argText)
+            => new SearchResult(commands, argText, null, null);
+        internal static SearchResult FromError(CommandError error, string reason)
+            => new SearchResult(null, null, error, reason);
+
+        public override string ToString() => IsSuccess ? "Success" : $"{Error}: {ErrorReason}";
+        private string DebuggerDisplay => IsSuccess ? $"Success ({Commands.Count} Results)" : $"{Error}: {ErrorReason}";
+    }
+}

src/Discord.Net.Commands/Results/TypeReaderResult.cs

@@ -0,0 +1,30 @@
+using System.Diagnostics;
+
+namespace Discord.Commands
+{
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public struct TypeReaderResult : IResult
+    {
+        public object Value { get; }
+
+        public CommandError? Error { get; }
+        public string ErrorReason { get; }
+
+        public bool IsSuccess => !Error.HasValue;
+
+        private TypeReaderResult(object value, CommandError? error, string errorReason)
+        {
+            Value = value;
+            Error = error;
+            ErrorReason = errorReason;
+        }
+
+        public static TypeReaderResult FromSuccess(object value)
+            => new TypeReaderResult(value, null, null);
+        public static TypeReaderResult FromError(CommandError error, string reason)
+            => new TypeReaderResult(null, error, reason);
+
+        public override string ToString() => IsSuccess ? "Success" : $"{Error}: {ErrorReason}";
+        private string DebuggerDisplay => IsSuccess ? $"Success ({Value})" : $"{Error}: {ErrorReason}";
+    }
+}