add Calculator system plugin

Wox.Plugin.System/Calculator.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Windows.Forms;
+using YAMP;
+
+namespace Wox.Plugin.System
+{
+    public class Calculator : BaseSystemPlugin
+    {
+        private static Regex regValidExpressChar = new Regex(
+                        @"^(" +
+                        @"sin|cos|ceil|floor|exp|pi|max|min|det|arccos|abs|" +
+                        @"eigval|eigvec|eig|sum|polar|plot|round|sort|real|zeta|" +
+                        @"bin2dec|hex2dec|oct2dec|" +
+                        @"==|~=|&&|\|\||" +
+                        @"[ei]|[0-9]|[\+\-\*\/\^\., ""]|[\(\)\|\!\[\]]" +
+                        @")+$", RegexOptions.Compiled);
+        private static Regex regBrackets = new Regex(@"[\(\)\[\]]", RegexOptions.Compiled);
+        private static ParseContext yampContext = null;
+        private PluginInitContext context { get; set; }
+
+        static Calculator()
+        {
+            yampContext = Parser.PrimaryContext;
+            Parser.InteractiveMode = false;
+            Parser.UseScripting = false;
+        }
+
+        protected override List<Result> QueryInternal(Query query)
+        {
+            if (string.IsNullOrEmpty(query.RawQuery)
+                || query.RawQuery.Length < 2          // don't affect when user only input "e" or "i" keyword
+                || !regValidExpressChar.IsMatch(query.RawQuery) 
+                || !IsBracketComplete(query.RawQuery)) return new List<Result>();
+
+            try
+            {
+                var result = yampContext.Run(query.RawQuery);
+                if (result.Output != null && !string.IsNullOrEmpty(result.Result))
+                {
+                    return new List<Result>() { new Result() { 
+                        Title = result.Result, 
+                        IcoPath = "Images/calculator.png", 
+                        Score = 300,
+                        SubTitle = "Copy this number to the clipboard", 
+                        Action = (c) =>
+                        {
+                            Clipboard.SetText(result.Result);
+                            return true;
+                        }
+                    } };
+                }
+            }
+            catch
+            {}
+
+            return new List<Result>();
+        }
+
+        private bool IsBracketComplete(string query)
+        {
+            var matchs = regBrackets.Matches(query);
+            var leftBracketCount = 0;
+            foreach (Match match in matchs)
+            {
+                if (match.Value == "(" || match.Value == "[")
+                {
+                    leftBracketCount++;
+                }
+                else
+                {
+                    leftBracketCount--;
+                }
+            }
+
+            return leftBracketCount == 0;
+        }
+
+        protected override void InitInternal(PluginInitContext context)
+        {
+            this.context = context;
+        }
+
+        
+    }
+}