Support for command line arguments (#155)

Source/GrasscutterTools/Utils/ToggleParser.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace GrasscutterTools.Utils
+{
+    /// <summary>
+    /// Simple command line toggles parser: 
+    ///  - toggles are identified with (any number of) '-' prefixes
+    ///  - toggle can be with or without associated value 
+    ///  - toggles are case-insensitive
+    /// 
+    /// <example>--toggle_without_value -toggle value</example>
+    /// <see cref="https://gist.github.com/jchapuis/64b5adf9d0f3062e6a72dded110a6028"/>
+    /// </summary>
+    internal class ToggleParser
+    {
+        private readonly Dictionary<string, string> toggles;
+
+        public ToggleParser(string[] args)
+        {
+            toggles =
+                args.Zip(args.Skip(1).Concat(new[] { string.Empty }), (first, second) => new { first, second })
+                    .Where(pair => IsToggle(pair.first))
+                    .ToDictionary(pair => RemovePrefix(pair.first).ToLowerInvariant(), g => IsToggle(g.second) ? string.Empty : g.second);
+        }
+
+        private static string RemovePrefix(string toggle)
+            => new string(toggle.SkipWhile(c => c == '-').ToArray());
+
+        private static bool IsToggle(string arg)
+            => arg.StartsWith("-", StringComparison.InvariantCulture);
+
+        public bool HasToggle(string toggle)
+            => toggles.ContainsKey(toggle.ToLowerInvariant());
+
+        public string GetToggleValueOrDefault(string toggle, string defaultValue)
+            => toggles.TryGetValue(toggle.ToLowerInvariant(), out var value) ? value : defaultValue;
+
+        public bool IsEmpty => toggles.Count == 0;
+    }
+}