Basic Working Version

It works. It's ugly and doesn't unsubscribe from clipboard events
correctly, but it works.

App.config

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+    <startup> 
+        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
+    </startup>
+</configuration>

App.xaml

@@ -0,0 +1,8 @@
+<Application x:Class="ClipboardRegex.App"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             StartupUri="MainWindow.xaml">
+    <Application.Resources>
+
+    </Application.Resources>
+</Application>

App.xaml.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Configuration;
+using System.Data;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace ClipboardRegex
+{
+    /// <summary>
+    /// Interaction logic for App.xaml
+    /// </summary>
+    public partial class App : Application
+    {
+    }
+}

ClipboardRegex.csproj

@@ -0,0 +1,104 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{129A0662-5FE4-493C-817B-51D64E1DD74C}</ProjectGuid>
+    <OutputType>WinExe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>ClipboardRegex</RootNamespace>
+    <AssemblyName>ClipboardRegex</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="System.Xaml">
+      <RequiredTargetFramework>4.0</RequiredTargetFramework>
+    </Reference>
+    <Reference Include="WindowsBase" />
+    <Reference Include="PresentationCore" />
+    <Reference Include="PresentationFramework" />
+  </ItemGroup>
+  <ItemGroup>
+    <ApplicationDefinition Include="App.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </ApplicationDefinition>
+    <Page Include="MainWindow.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </Page>
+    <Compile Include="App.xaml.cs">
+      <DependentUpon>App.xaml</DependentUpon>
+      <SubType>Code</SubType>
+    </Compile>
+    <Compile Include="MainWindow.xaml.cs">
+      <DependentUpon>MainWindow.xaml</DependentUpon>
+      <SubType>Code</SubType>
+    </Compile>
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Properties\AssemblyInfo.cs">
+      <SubType>Code</SubType>
+    </Compile>
+    <Compile Include="Properties\Resources.Designer.cs">
+      <AutoGen>True</AutoGen>
+      <DesignTime>True</DesignTime>
+      <DependentUpon>Resources.resx</DependentUpon>
+    </Compile>
+    <Compile Include="Properties\Settings.Designer.cs">
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Settings.settings</DependentUpon>
+      <DesignTimeSharedInput>True</DesignTimeSharedInput>
+    </Compile>
+    <EmbeddedResource Include="Properties\Resources.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>Resources.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+    <None Include="Properties\Settings.settings">
+      <Generator>SettingsSingleFileGenerator</Generator>
+      <LastGenOutput>Settings.Designer.cs</LastGenOutput>
+    </None>
+    <AppDesigner Include="Properties\" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="App.config" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>

MainWindow.xaml

@@ -0,0 +1,24 @@
+<Window x:Class="ClipboardRegex.MainWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Enter Regex to apply to clipboard copies here" Height="140" Width="525">
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition/>
+            <RowDefinition/>
+            <RowDefinition/>
+        </Grid.RowDefinitions>
+
+        <TextBox x:Name="FindWhat" Text="Find What" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" FontFamily="Cambria" FontSize="16" Grid.Row="0"/>
+        <TextBox x:Name="ReplaceWith" Text="Replace With" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" FontFamily="Cambria" FontSize="16" Grid.Row="1"/>
+        <Grid Grid.Row="2">
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition/>
+                <ColumnDefinition/>
+            </Grid.ColumnDefinitions>
+            <CheckBox x:Name="MultLineOpt" Content="Multiline?" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Column="0" IsChecked="True"/>
+            <CheckBox x:Name="DotMatchNL" Content=". matches newline?" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Column="1" IsChecked="True"/>
+        </Grid>        
+
+    </Grid>
+</Window>

MainWindow.xaml.cs

@@ -0,0 +1,128 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+using System.Runtime.InteropServices;
+using System.Windows.Interop;
+using System.Text.RegularExpressions;
+
+namespace ClipboardRegex
+{
+    /// <summary>
+    /// Interaction logic for MainWindow.xaml
+    /// </summary>
+    public partial class MainWindow : Window
+    {
+        DateTime lastProcessed;
+        static TimeSpan hundredMS = new TimeSpan(0, 0, 0, 0, 100);
+
+        public MainWindow()
+        {
+            InitializeComponent();
+            lastProcessed = DateTime.Now;
+
+        }
+
+        // Clipboard code taken from http://www.fluxbytes.com/csharp/how-to-monitor-for-clipboard-changes-using-addclipboardformatlistener/
+        /// <summary>
+        /// Places the given window in the system-maintained clipboard format listener list.
+        /// </summary>
+        [DllImport("user32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        static extern bool AddClipboardFormatListener(IntPtr hwnd);
+
+        /// <summary>
+        /// Removes the given window from the system-maintained clipboard format listener list.
+        /// </summary>
+        [DllImport("user32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        static extern bool RemoveClipboardFormatListener(IntPtr hwnd);
+
+        /// <summary>
+        /// Sent when the contents of the clipboard have changed.
+        /// </summary>
+        private const int WM_CLIPBOARDUPDATE = 0x031D;
+
+        // Event-processing code adapted from http://stackoverflow.com/a/1926796/
+        protected override void OnSourceInitialized(EventArgs e)
+        {
+            base.OnSourceInitialized(e);
+            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
+            source.AddHook(WndProc);
+
+            bool result = AddClipboardFormatListener(source.Handle);
+            if (!result)
+            {
+                var err = Marshal.GetLastWin32Error();
+                Console.WriteLine(err);
+            }
+            Console.WriteLine(result);
+
+        }
+
+        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
+        {
+            if (msg == WM_CLIPBOARDUPDATE)
+            {
+                if ((DateTime.Now - lastProcessed) > hundredMS) // Hack to avoid feedback loop
+                {
+                    IDataObject iData = Clipboard.GetDataObject();      // Clipboard's data.
+
+                    /* Depending on the clipboard's current data format we can process the data differently. 
+                     * Feel free to add more checks if you want to process more formats. */
+                    if (iData.GetDataPresent(DataFormats.Text))
+                    {
+                        string text = (string)iData.GetData(DataFormats.Text);
+                        Clipboard.SetText(runUserRegex(text));
+                    }
+                    lastProcessed = DateTime.Now;
+                }               
+
+            }
+
+            return IntPtr.Zero;
+        }
+
+        private string runUserRegex(string input)
+        {
+            if (!MultLineOpt.IsChecked.HasValue || !DotMatchNL.IsChecked.HasValue)
+            {
+                return input; // Should never happen
+            }
+                string pattern = FindWhat.Text;
+                string replacement = ReplaceWith.Text;
+                RegexOptions opts = (bool)MultLineOpt.IsChecked ? RegexOptions.Multiline : RegexOptions.None;
+                opts |= (bool)DotMatchNL.IsChecked ? RegexOptions.Singleline : RegexOptions.None;
+
+                try
+                {
+                    return System.Text.RegularExpressions.Regex.Replace(input, pattern, replacement, opts, new TimeSpan(0, 0, 1));
+                }
+                catch (ArgumentException)
+                {
+                    MessageBox.Show("Invalid Regular Expression");
+                    return input;
+                }
+
+        }
+
+
+
+
+    }
+
+
+
+
+
+}

Properties/AssemblyInfo.cs

@@ -0,0 +1,55 @@
+using System.Reflection;
+using System.Resources;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Windows;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("ClipboardRegex")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("ClipboardRegex")]
+[assembly: AssemblyCopyright("Copyright ©  2015")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible 
+// to COM components.  If you need to access a type in this assembly from 
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+//In order to begin building localizable applications, set 
+//<UICulture>CultureYouAreCodingWith</UICulture> in your .csproj file
+//inside a <PropertyGroup>.  For example, if you are using US english
+//in your source files, set the <UICulture> to en-US.  Then uncomment
+//the NeutralResourceLanguage attribute below.  Update the "en-US" in
+//the line below to match the UICulture setting in the project file.
+
+//[assembly: NeutralResourcesLanguage("en-US", UltimateResourceFallbackLocation.Satellite)]
+
+
+[assembly: ThemeInfo(
+    ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
+    //(used if a resource is not found in the page, 
+    // or application resource dictionaries)
+    ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
+    //(used if a resource is not found in the page, 
+    // app, or any theme specific resource dictionaries)
+)]
+
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers 
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]