Fix a few error cases

Author: govert

Source/ExcelDna.IntelliSense.Host/MyFunctions.cs

@@ -22,6 +22,18 @@ public static string jDummyFunc()
                 return "Howzit !";
             }
 
+            [ExcelFunction]
+            public static object AnotherFunction( [Description("In and out")] object inout)
+            {
+                return inout;
+            }
+
+            [ExcelFunction]
+            public static object ANonDescriptFunction(object inout)
+            {
+                return inout;
+            }
+
         }
     }
 #endif

Source/ExcelDna.IntelliSense/ExcelDna.IntelliSense.csproj

@@ -57,6 +57,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="FormattedText.cs" />
+    <Compile Include="FormulaParser.cs" />
     <Compile Include="IntelliSenseDisplay.cs" />
     <Compile Include="IntelliSenseHelper.cs" />
     <Compile Include="IntelliSenseProvider.cs" />

Source/ExcelDna.IntelliSense/FormattedText.cs

@@ -18,7 +18,7 @@ public FormattedText()
 
         public void Add(TextLine line) { _lines.Add(line); }
 
-        public void Add(IEnumerable<TextLine> lines) { _lines.AddRange(lines); }
+        public void Add(IEnumerable<TextLine> lines) { if (lines != null) _lines.AddRange(lines); }
 
         public IEnumerator<TextLine> GetEnumerator()
         {

Source/ExcelDna.IntelliSense/FormulaParser.cs

@@ -0,0 +1,23 @@
+using System.Linq;
+using System.Text.RegularExpressions;
+
+namespace ExcelDna.IntelliSense
+{
+    static class FormulaParser
+    {
+        // TODO: This needs a proper implementation, considering subformulae
+        internal static bool TryGetFormulaInfo(string formulaPrefix, out string functionName, out int currentArgIndex)
+        {
+            var match = Regex.Match(formulaPrefix, @"^=(?<functionName>\w*)\(");
+            if (match.Success)
+            {
+                functionName = match.Groups["functionName"].Value;
+                currentArgIndex = formulaPrefix.Count(c => c == ',');
+                return true;
+            }
+            functionName = null;
+            currentArgIndex = -1;
+            return false;
+        }
+    }
+}

Source/ExcelDna.IntelliSense/IntelliSenseDisplay.cs

@@ -235,21 +235,19 @@ void FormulaEditMove(Rect editWindowBounds, Rect excelTooltipBounds)
         void FormulaEditTextChange(string formulaPrefix, Rect editWindowBounds, Rect excelTooltipBounds)
         {
             Debug.Print($"^^^ FormulaEditStateChanged. CurrentPrefix: {formulaPrefix}, Thread {Thread.CurrentThread.ManagedThreadId}");
-            var match = Regex.Match(formulaPrefix, @"^=(?<functionName>\w*)\(");
-            if (match.Success)
+            string functionName;
+            int currentArgIndex;
+            if (FormulaParser.TryGetFormulaInfo(formulaPrefix, out functionName, out currentArgIndex))
             {
-                string functionName = match.Groups["functionName"].Value;
-
                 IntelliSenseFunctionInfo functionInfo;
                 if (_functionInfoMap.TryGetValue(functionName, out functionInfo))
                 {
-                    // TODO: Fix this: Need to consider subformulae
-                    int currentArgIndex = formulaPrefix.Count(c => c == ',');
                     _argumentsToolTip.ShowToolTip(
                         GetFunctionIntelliSense(functionInfo, currentArgIndex),
                         (int)editWindowBounds.Left, (int)editWindowBounds.Bottom + 5);
                     return;
                 }
+
             }
 
             // All other paths, we hide the box
@@ -288,15 +286,19 @@ void FunctionListSelectedItemChange(string selectedItemText, Rect selectedItemBo
             if (_functionInfoMap.TryGetValue(selectedItemText, out functionInfo))
             {
                 // It's ours!
-                _descriptionToolTip.ShowToolTip(
-                    text: new FormattedText { GetFunctionDescription(functionInfo) },
-                    left: (int)selectedItemBounds.Right + 25,
-                    top: (int)selectedItemBounds.Top);
-            }
-            else
-            {
-                _descriptionToolTip.Hide();
+                var descriptionLines = GetFunctionDescriptionOrNull(functionInfo);
+                if (descriptionLines != null)
+                {
+                    _descriptionToolTip.ShowToolTip(
+                        text: new FormattedText { GetFunctionDescriptionOrNull(functionInfo) },
+                        left: (int)selectedItemBounds.Right + 25,
+                        top: (int)selectedItemBounds.Top);
+                    return;
+                }
             }
+
+            // Not ours or no description
+            _descriptionToolTip.Hide();
         }
 
         void FunctionListMove(Rect selectedItemBounds)
@@ -307,18 +309,20 @@ void FunctionListMove(Rect selectedItemBounds)
         // TODO: Performance / efficiency - cache these somehow
         // TODO: Probably not a good place for LINQ !?
         static readonly string[] s_newLineStringArray = new string[] { Environment.NewLine };
-        IEnumerable<TextLine> GetFunctionDescription(IntelliSenseFunctionInfo functionInfo)
+        IEnumerable<TextLine> GetFunctionDescriptionOrNull(IntelliSenseFunctionInfo functionInfo)
         {
-            return 
-                functionInfo.Description
-                .Split(s_newLineStringArray, StringSplitOptions.None)
-                .Select(line => 
-                    new TextLine { 
-                        new TextRun
-                        {
-                            Style = System.Drawing.FontStyle.Regular,
-                            Text = line
-                        }});
+            var description = functionInfo.Description;
+            if (string.IsNullOrEmpty(description))
+                return null;
+
+            return description.Split(s_newLineStringArray, StringSplitOptions.None)
+                              .Select(line => 
+                                new TextLine { 
+                                    new TextRun
+                                    {
+                                        Style = System.Drawing.FontStyle.Regular,
+                                        Text = line
+                                    }});
         }
 
         FormattedText GetFunctionIntelliSense(IntelliSenseFunctionInfo functionInfo, int currentArgIndex)
@@ -357,12 +361,13 @@ FormattedText GetFunctionIntelliSense(IntelliSenseFunctionInfo functionInfo, int
             }
             nameLine.Add(new TextRun { Text = ")" });
 
-            var descriptionLines = GetFunctionDescription(functionInfo);
+            var descriptionLines = GetFunctionDescriptionOrNull(functionInfo);
 
             var formattedText = new FormattedText { nameLine, descriptionLines };
             if (functionInfo.ArgumentList.Count > currentArgIndex)
             {
-                formattedText.Add(GetArgumentDescription(functionInfo.ArgumentList[currentArgIndex]));
+                var description = GetArgumentDescription(functionInfo.ArgumentList[currentArgIndex]);
+                formattedText.Add(description);
             }
 
             return formattedText;
@@ -379,7 +384,7 @@ TextLine GetArgumentDescription(IntelliSenseFunctionInfo.ArgumentInfo argumentIn
                     new TextRun
                     {
                         Style = System.Drawing.FontStyle.Italic,
-                        Text = argumentInfo.Description
+                        Text = argumentInfo.Description ?? ""
                     },
                 };
         }
@@ -399,6 +404,7 @@ public void Dispose()
                         _argumentsToolTip.Dispose();
                         _argumentsToolTip = null;
                     }
+                    _uiMonitor.Dispose();
                 }, null);
 
             _syncContextMain = null;