Simplify adding handlers to builtin functions

Author: lzybkr

GenerateBuiltinList.ps1

@@ -0,0 +1,47 @@
+
+# Generate the ValidateSet attribute for the Builtin parameter
+# Set-PSReadlineKeyHandler
+
+$methods = ([PSConsoleUtilities.PSConsoleReadLine] |
+    Get-Member -Static -Type Method |
+    Where-Object Definition -match .*Nullable.*).Name
+
+$indent = " " * 8
+$prefix = "[ValidateSet("
+$suffix = "]"
+
+function GenerateStrings
+{
+    param([Parameter(ValueFromPipeline)]$Item)
+
+    begin
+    {
+        $count = 0
+        $comma = ""
+        $buffer = New-Object System.Text.StringBuilder
+    }
+
+    process
+    {
+        $null = $buffer.Append($comma)
+        $count++
+        if (($count % 5) -eq 0)
+        {
+            # Remove the trailing space
+            $null = $buffer.Remove($buffer.Length - 1, 1)
+            $null = $buffer.Append("`n$indent$(' ' * $prefix.Length)")
+        }
+        $null = $buffer.Append('"')
+        $null = $buffer.Append($Item)
+        $null = $buffer.Append('"')
+
+        $comma = ", "
+    }
+
+    end
+    {
+        $buffer.ToString()
+    }
+}
+
+"$indent$prefix$($methods | GenerateStrings))$suffix"

PSReadLine/Cmdlets.cs

@@ -186,20 +186,45 @@ public class SetKeyHandlerCommand : PSCmdlet
         [ValidateNotNullOrEmpty]
         public string[] Chord { get; set; }
 
-        [Parameter(Position = 1, Mandatory = true)]
+        [Parameter(Position = 1, Mandatory = true, ParameterSetName = "Custom")]
         [ValidateNotNull]
-        public Action<ConsoleKeyInfo?, object> Handler { get; set; }
+        public ScriptBlock Handler { get; set; }
 
-        [Parameter(Mandatory = true)]
+        [Parameter(ParameterSetName = "Custom")]
         public string BriefDescription { get; set; }
 
-        [Parameter]
+        [Parameter(ParameterSetName = "Custom")]
         public string LongDescription { get; set; }
 
+        // ValidateSet attribute is generated by the script GenerateBuiltinList
+        [ValidateSet("AcceptLine", "AddLine", "BackwardChar", "BackwardDeleteChar",
+                     "BackwardDeleteLine", "BackwardKillLine", "BackwardWord", "BeginningOfHistory", "BeginningOfLine",
+                     "CancelLine", "Complete", "DeleteChar", "DisableDemoMode", "EmacsBackwardWord",
+                     "EmacsForwardWord", "EnableDemoMode", "EndOfHistory", "EndOfLine", "ExchangePointAndMark",
+                     "ForwardChar", "ForwardDeleteLine", "ForwardWord", "HistorySearchBackward", "HistorySearchForward",
+                     "KillBackwardWord", "KillLine", "KillWord", "NextHistory", "Paste",
+                     "PossibleCompletions", "PreviousHistory", "Redo", "RevertLine", "SetKeyHandler",
+                     "SetMark", "TabCompleteNext", "TabCompletePrevious", "Undo", "Yank",
+                     "YankPop")]
+        [Parameter(Position = 1, Mandatory = true, ParameterSetName = "Builtin")]
+        public string Builtin { get; set; }
+
         [ExcludeFromCodeCoverage]
         protected override void EndProcessing()
         {
-            PSConsoleReadLine.SetKeyHandler(Chord, Handler, BriefDescription, LongDescription);
+            Action<ConsoleKeyInfo?, object> keyHandler;
+            if (ParameterSetName.Equals("Builtin"))
+            {
+                keyHandler = (Action<ConsoleKeyInfo?, object>)
+                    Delegate.CreateDelegate(typeof (Action<ConsoleKeyInfo?, object>),
+                                            typeof (PSConsoleReadLine).GetMethod(Builtin));
+                BriefDescription = Builtin;
+            }
+            else
+            {
+                keyHandler = (key, arg) => Handler.Invoke(key, arg);
+            }
+            PSConsoleReadLine.SetKeyHandler(Chord, keyHandler, BriefDescription, LongDescription);
         }
     }