3 files changed, 42 insertions, 8 deletions

diff --git a/src/WixToolset.Extensibility/Services/ICommandLineArguments.cs b/src/WixToolset.Extensibility/Services/ICommandLineArguments.cs
new file mode 100644
index 00000000..eb1f8765
--- /dev/null
+++ b/src/WixToolset.Extensibility/Services/ICommandLineArguments.cs
@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility.Services
+{
+    using System.Collections.Generic;
+
+    public interface ICommandLineArguments
+    {
+        string[] OriginalArguments { get; set; }
+
+        string[] Arguments { get; set; }
+
+        string[] Extensions { get; set; }
+
+        string ErrorArgument { get; set; }
+
+        void Populate(string commandLine);
+
+        void Populate(string[] args);
+
+        IParseCommandLine Parse();
+    }
+}
diff --git a/src/WixToolset.Extensibility/Services/ICommandLineContext.cs b/src/WixToolset.Extensibility/Services/ICommandLineContext.cs
index 27d4e6dd..84b9654f 100644
--- a/src/WixToolset.Extensibility/Services/ICommandLineContext.cs
+++ b/src/WixToolset.Extensibility/Services/ICommandLineContext.cs
@@ -12,8 +12,6 @@ namespace WixToolset.Extensibility.Services
 
         IExtensionManager ExtensionManager { get; set; }
 
-        string Arguments { get; set; }
-
-        string[] ParsedArguments { get; set; }
+        ICommandLineArguments Arguments { get; set; }
     }
 }
diff --git a/src/WixToolset.Extensibility/Services/IParseCommandLine.cs b/src/WixToolset.Extensibility/Services/IParseCommandLine.cs
index 1b23be14..3753b4f2 100644
--- a/src/WixToolset.Extensibility/Services/IParseCommandLine.cs
+++ b/src/WixToolset.Extensibility/Services/IParseCommandLine.cs
@@ -6,16 +6,29 @@ namespace WixToolset.Extensibility.Services
 
     public interface IParseCommandLine
     {
+        string ErrorArgument { get; set; }
+
+        /// <summary>
+        /// Validates that a valid switch (starts with "/" or "-"), and returns a bool indicating its validity
+        /// </summary>
+        /// <param name="arg">The string check.</param>
+        /// <returns>True if a valid switch, otherwise false.</returns>
         bool IsSwitch(string arg);
 
-        bool IsSwitchAt(IEnumerable<string> args, int index);
+        void GetArgumentAsFilePathOrError(string argument, string fileType, IList<string> paths);
+
+        string GetNextArgumentOrError(string commandLineSwitch);
+
+        bool GetNextArgumentOrError(string commandLineSwitch, IList<string> argument);
+
+        string GetNextArgumentAsDirectoryOrError(string commandLineSwitch);
 
-        void GetNextArgumentOrError(ref string arg);
+        bool GetNextArgumentAsDirectoryOrError(string commandLineSwitch, IList<string> directories);
 
-        void GetNextArgumentOrError(IList<string> args);
+        string GetNextArgumentAsFilePathOrError(string commandLineSwitch);
 
-        void GetNextArgumentAsFilePathOrError(IList<string> args, string fileType);
+        bool GetNextArgumentAsFilePathOrError(string commandLineSwitch, string fileType, IList<string> paths);
 
-        bool TryGetNextArgumentOrError(out string arg);
+        bool TryGetNextSwitchOrArgument(out string arg);
     }
 }