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StackOverflow in SelectSingleNode

Hello I have function which creates/updates fields in app.exe.config file
public static void UpdateConfig(string FieldName, string FieldValue, ConfigSelector SectionName = ConfigSelector.AppSettings)
{
switch (SectionName)
{
case ConfigSelector.Execption:
{
// MessageBox.Show("gg");
var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
if (xmlDoc.SelectSingleNode("configuration/Execption") != null)
{
if (xmlDoc.SelectSingleNode("configuration/Execption/List") != null)
{
// create new node <add key="Region" value="Canterbury" />
var nodeRegion = xmlDoc.CreateElement("add");
nodeRegion.SetAttribute("key", FieldName);
nodeRegion.SetAttribute("value", FieldValue);
xmlDoc.SelectSingleNode("configuration/Execption/List").AppendChild(nodeRegion);
}
else
{
var List = xmlDoc.CreateElement("List");
xmlDoc.SelectSingleNode("configuration/Execption").AppendChild(List);
UpdateConfig(FieldName, FieldValue, SectionName);
}
}
else
{
var List = xmlDoc.CreateElement("Execption");
xmlDoc.SelectSingleNode("configuration").AppendChild(List);
UpdateConfig(FieldName, FieldValue, SectionName);
}
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
ConfigurationManager.RefreshSection("Execption/List");
break;
}
}
}
Function works first Check if xpath configuration/Execption exist, if not exist it creates this path and recalls function again, second time check if configuration/Execption/List path exist if not creates path and recalls function again, and third time adds required fields which is fieldname and fieldvalue,
but I getting System.StackOverflowException in line:
if (xmlDoc.SelectSingleNode("configuration/Execption") != null)
Did I miss something?

You are calling UpdateConfig recursively, with the exact same arguments already passed to it
UpdateConfig(FieldName, FieldValue, SectionName);
Since the recursive call happens before the xmlDoc.Save(), it always works on the same content.
Saving before doing the recursive call should fix the issue.

You don't save the document after adding the new element, so when you are loading the file in the next iteration the new element isn't there, and xmlDoc.SelectSingleNode("configuration/Execption") != null is still false, so the code creates the element again in infinite recursion and you get StackOverflowException.
Just save the document after you change it
else
{
var List = xmlDoc.CreateElement("Execption");
xmlDoc.SelectSingleNode("configuration").AppendChild(List);
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
UpdateConfig(FieldName, FieldValue, SectionName);
}

How to use a Variable Name which was Obtained at Run-Time

All, to provide a on-the-fly mechanism for debugging an application in different languages I am using the required resource string (in a foreign language) to display the English equivalent at run-time should the user require it. This is done using
public static string GetMessage(string messageKey)
{
CultureInfo culture = Thread.CurrentThread.CurrentCulture;
if (!culture.DisplayName.Contains("English"))
{
string fileName = "MessageStrings.resx";
string appDir = Path.GetDirectoryName(Application.ExecutablePath);
fileName = Path.Combine(appDir, fileName);
if (File.Exists(fileName))
{
// Get the English error message.
using (ResXResourceReader resxReader = new ResXResourceReader(fileName))
{
foreach (DictionaryEntry e in resxReader)
if (e.Key.ToString().CompareNoCase(messageKey) == 0)
return e.Value.ToString();
}
}
}
return null;
}
Where GetName is defined as
public static string GetName<T>(Expression<Func<T>> expression)
{
return ((MemberExpression)expression.Body).Member.Name;
}
I usually display localised messages in my application like
Utils.ErrMsg(MessageStrings.SomeMessage);
or
Utils.ErrMsg(String.Format(MessageStrings.SomeMessage, param1, param2));
Now I can display the relevent English message from my app running in a different culture using
Utils.ErrMsg(Utils.GetMessage(
Utils.GetName(() => MessageStrings.ErrCellAllocStatZeroTotal)) ??
MessageStrings.ErrCellAllocStatZeroTotal);
I want to avoid having to use a lambda expression in the call to GetName and the use of null from GetMessage and using ??, how can I achieve this [if at all possible]?
Thanks for your time.

I do not fully understand your code, but if you just want to access the properties of an object dynamically, try this (you have to replace [Object] and "PropertyName" with your specific values):
// get the property from object
PropertyInfo Property = [Object].GetType().GetProperty("PropertyName");
// get the value
int value = (int)Property.GetValue([Object], null);

ReSharper "Possible NullReferenceException" wrong with FileInfo?

I just started using ReSharper and I'm trying to identify why it thinks this code is wrong.
var file = new FileInfo("foobar");
return file.Directory.FullName;
It highlights file.Directory as a "Possible System.NullReferenceException". I'm not sure how this is possible because the file object can never be null and I can't figure out how the DirectoryInfo object returned from the FileInfo object could ever be null.

The Directory property can indeed be null. The implementation of the property is roughly
public DirectoryInfo Directory {
get {
string directoryName = this.DirectoryName;
if (directoryName == null) {
return null;
}
return new DirectoryInfo(directoryName);
}
}
It can definitely return null. Here is a concrete example
var x = new FileInfo(#"c:\");
if (x.Directory == null) {
Console.WriteLine("Directory is null"); // Will print
}

Analysing C# source with Irony

This is what my team and I chose to do for our school project. Well, actually we haven't decided on how to parse the C# source files yet.
What we are aiming to achieve is, perform a full analysis on a C# source file, and produce up a report.
In which the report is going to contain stuff that happening in the codes.
The report only has to contain:
string literals
method names
variable names
field names
etc
I'm in charge of looking into this Irony library. To be honest, I don't know the best way to sort the data out into a clean readable report. I am using the C# grammar class packed with the zip.
Is there any step where I can properly identify each node children? (eg: using directives, namespace declaration, class declaration etc, method body)
Any help or advice would be very much appreciated. Thanks.
EDIT: Sorry I forgot to say we need to analysis the method calls too.

Your main goal is to master the basics of formal languages. A good start-up might be found here. This article describes the way to use Irony on the sample of a grammar of a simple numeric calculator.
Suppose you want to parse a certain file containing C# code the path to which you know:
private void ParseForLongMethods(string path)
{
_parser = new Parser(new CSharpGrammar());
if (_parser == null || !_parser.Language.CanParse()) return;
_parseTree = null;
GC.Collect(); //to avoid disruption of perf times with occasional collections
_parser.Context.SetOption(ParseOptions.TraceParser, true);
try
{
string contents = File.ReadAllText(path);
_parser.Parse(contents);//, "<source>");
}
catch (Exception ex)
{
}
finally
{
_parseTree = _parser.Context.CurrentParseTree;
TraverseParseTree();
}
}
And here is the traversal method itself with counting some info in the nodes. Actually this code counts the number of statements in every method of the class. If you have any question you are always welcome to ask me
private void TraverseParseTree()
{
if (_parseTree == null) return;
ParseNodeRec(_parseTree.Root);
}
private void ParseNodeRec(ParseTreeNode node)
{
if (node == null) return;
string functionName = "";
if (node.ToString().CompareTo("class_declaration") == 0)
{
ParseTreeNode tmpNode = node.ChildNodes[2];
currentClass = tmpNode.AstNode.ToString();
}
if (node.ToString().CompareTo("method_declaration") == 0)
{
foreach (var child in node.ChildNodes)
{
if (child.ToString().CompareTo("qual_name_with_targs") == 0)
{
ParseTreeNode tmpNode = child.ChildNodes[0];
while (tmpNode.ChildNodes.Count != 0)
{ tmpNode = tmpNode.ChildNodes[0]; }
functionName = tmpNode.AstNode.ToString();
}
if (child.ToString().CompareTo("method_body") == 0) //method_declaration
{
int statementsCount = FindStatements(child);
//Register bad smell
if (statementsCount>(((LongMethodsOptions)this.Options).MaxMethodLength))
{
//function.StartPoint.Line
int functionLine = GetLine(functionName);
foundSmells.Add(new BadSmellRegistry(name, functionLine,currentFile,currentProject,currentSolution,false));
}
}
}
}
foreach (var child in node.ChildNodes)
{ ParseNodeRec(child); }
}

I'm not sure this is what you need but you could use the CodeDom and CodeDom.Compiler namespaces to compile the C# code, and than analyze the results using Reflection, something like:
// Create assamblly in Memory
CodeSnippetCompileUnit code = new CodeSnippetCompileUnit(classCode);
CSharpCodeProvider provider = new CSharpCodeProvider();
CompilerResults results = provider.CompileAssemblyFromDom(compileParams, code);
foreach(var type in results.CompiledAssembly)
{
// Your analysis go here
}
Update: In VS2015 you could use the new C# compiler (AKA Roslyn) to do the same, for example:
var root = (CompilationUnitSyntax)tree.GetRoot();
var compilation = CSharpCompilation.Create("HelloTDN")
.AddReferences(references: new[] { MetadataReference.CreateFromAssembly(typeof(object).Assembly) })
.AddSyntaxTrees(tree);
var model = compilation.GetSemanticModel(tree);
var nameInfo = model.GetSymbolInfo(root.Usings[0].Name);
var systemSymbol = (INamespaceSymbol)nameInfo.Symbol;
foreach (var ns in systemSymbol.GetNamespaceMembers())
{
Console.WriteLine(ns.Name);
}

C# Cut/Copy & Paste objects

This is a 2 parter.
First I am having a heck of a time getting the paste part of a copy and paste operation to work.
I have a method that copies information to the Clipboard, works perfectly.
private void CopyData(string format, object data, string text)
{
bool addedData = false;
DataObject copyData = new DataObject();
if (!string.IsNullOrEmpty(text))
{
copyData.SetData(DataFormats.Text, text);
addedData = true;
}
if (!string.IsNullOrEmpty(format) && data != null)
{
copyData.SetData(format, false, data);
addedData = true;
//this is only for testing
object obj = null;
if (copyData.GetDataPresent(format))
obj = (object)copyData.GetData(format);
}
if (addedData)
Clipboard.SetDataObject(copyData, true);
}
When I check that the data was added the object (obj) is not null.
However when I then go to paste the data from a different method using the same format key I get null, every time.
private void PasteFromClipboard()
{
object obj = null;
IDataObject paste = null;
if (Clipboard.GetDataObject().GetDataPresent("mydatatype"))
obj = (object)Clipboard.GetDataObject().GetData("mydatatype");
else
return;
if (obj == null)
throw new NullReferenceException("Could not gather information from the
}
I have tried everything that I can think of and it just doesn't make sense. I created an array of strings to capture all of the format keys the DataObject was holding and "mydatatype" was the first one. I have tried casting, not casting, using (Clipboard.GetDataObject().GetData("mydatatype") as object) and I just cannot figure it out. I know that there is data there because I can go to NotePad and paste the text that I copied along with the object.
Any thoughts as to why I would be able to get the data in one method, but not another?
Secondly I was wondering how I would go about making a Cut & Paste operation work between two of my windows. I am thinking about something like Excel, where if only the text is pasted the data will remain, however if the objects are pasted then the source will be deleted.
Thanks
Patrick.

Try pulling the data out as Text (instead of "mydatatype") - at least to confirm you can read from the clipboard. This is most likely what Notepad is reading. Also, does it matter that you're copying with "format" but pasting with "mydatatype"?

Could it be that text parameter always has a value and gets set. Then possibly the second if the one that would set the object does not get executed. Or if it does since the data was set in the first if statement the second set fails to set it correctly.
My recommendation would be to walk the code in the debugger during the copy operation.

Before the paste use GetDataObject().GetFormats() to enumerate the list of formatting codes.
Perhaps your using the wrong one.. just an idea

Try using reflection like this:
private static T TryGetClipboardData<T>(IDataObject clipboardData, string dataFormat)
{
System.Reflection.FieldInfo fieldInfo = clipboardData.GetType().GetField("innerData", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var outerData = fieldInfo.GetValue(clipboardData);
if (outerData == null)
{
return default(T);
}
fieldInfo = outerData.GetType().GetField("innerData", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var innerData = fieldInfo.GetValue(outerData);
if (innerData is System.Runtime.InteropServices.ComTypes.IDataObject)
{
// It is (probably) necessary to wrap COM IDataObject to Windows.Forms.IDataObject
System.Windows.Forms.DataObject wrappedDataObject = new System.Windows.Forms.DataObject(innerData);
var data = wrappedDataObject.GetData(dataFormat);
if (data is T)
{
return (T)data;
}
}
return default(T);
}
I suspect the COM object of your data in the Clipboard had a difficult time converting itself to the format you specified. I'm also playing safe with the input format string so that it is registered as a proper clipboard format.
HTH