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Custom keyword coloring in Visual Studio 2010+

I'm trying to add custom coloring for only certain keywords in my Visual Studio editor for C# code. I want to be able to color any type that implements IDisposable as a different color. Ideally I'd like to create a simple list of classes/interfaces that derive from IDisposable in some sort of configuration that I can edit. (Although if you said there was a method/plugin that would automatically find all disposable types and color them independently that would be the Holy Grail).
I've done a ton of research and it looks like an "editor classifier" extension might do the trick. However I created one that merely tries to color the word "Stream" and although it does hit my code that attempts to highlight that word, it does not end up highlighted in the editor.
I have added my VS extension to Github here
This really seems like this should be fairly straightforward but I have gone down many alleys on this one only to find dead-ends. Is there a simpler way to do this, or is my extension broken?
Update
Very strange. I just ran my extension again and although it does not highlight the text in the editor it highlights all instances of "Stream" in the popup text when you hover over a type/variable! Is there any way to get it to apply to the editor?

Depending on wether you are using Jetbrains Resharper or not you may write a plugin for that. That way you are able not only to add visual notification of IDisposable on a variable but also provide quickfixes if, and only if, it is not beeing called, which is what i am assuming you want to catch. Mind you that i can imagine that there's already a R# plugin for that. I know i've considered this too, but i was too lazy to write a plugin for that.
Don't get me wrong btw - If you're not using r# yet you should consider trying it out.
Among others you'd be working with this: API-QuickFix
There are also ways to define custom keywords, as resharper does, given by a custom markup and apply quickfixes to that.
PS: No i don't work at jetbrains. it's just that good :)
UPDATE:
potential VS Extension fix?
check this one out: MSDN Link Highlighting Text
I tried opening your github project but couldn't so i thought i'll just check msdn instead. it seems you are deriving from the wrong class to fulfill your needs?
MSDN keyword "Editors - Extending the Editor - Walkthrough: Highlighting Text"
I know SO wants code on the site, but msdn links going down is rather unlikely and with the given information the content can be found easily enough :)

I'm a bit late to the party, but hey, why not throw my 2 cents in.
As you've explained in your question, your project has two basic parts:
Finding the classes that implement IDisposable
Highlighting them
The first is by far the hardest, though not impossible. A word-list based approach is probably the simplest, though it should be possible with Roslyn to figure out on the fly which classes inherit IDisposible.
You could also always resort to loading the project's compiled .exe/.dll in the background after a build and figuring out what the types are there, but you'd still have to write some magic glue code to figure out what short class names in the code referred to what actual full-name classes in the assembly.
The second part, highlighting, is quite easy once you know how to do it (it helps that I've spent the last several months working full-time on extending VS). Of course, with Visual Studio, nothing is as simple as it looks (despite the efforts of Microsoft to try to make it user-friendly). So, I've built a sample extension that highlights just classes named "Stream" within C# files to get you started.
The relevant code is below, and the full project source is on GitHub). It starts with a classification-tagger provider:
[Export(typeof(ITaggerProvider))]
[ContentType("CSharp")]
[TagType(typeof(ClassificationTag))]
[Name("HighlightDisposableTagger")]
public class HighlightDisposableTaggerProvider : ITaggerProvider
{
[Import]
private IClassificationTypeRegistryService _classificationRegistry = null;
[Import]
private IClassifierAggregatorService _classifierAggregator = null;
private bool _reentrant;
public ITagger<T> CreateTagger<T>(ITextBuffer buffer) where T : ITag
{
if (_reentrant)
return null;
try {
_reentrant = true;
var classifier = _classifierAggregator.GetClassifier(buffer);
return new HighlightDisposableTagger(buffer, _classificationRegistry, classifier) as ITagger<T>;
}
finally {
_reentrant = false;
}
}
}
Then the tagger itself:
public class HighlightDisposableTagger : ITagger<ClassificationTag>
{
private const string DisposableFormatName = "HighlightDisposableFormat";
[Export]
[Name(DisposableFormatName)]
public static ClassificationTypeDefinition DisposableFormatType = null;
[Export(typeof(EditorFormatDefinition))]
[Name(DisposableFormatName)]
[ClassificationType(ClassificationTypeNames = DisposableFormatName)]
[UserVisible(true)]
public class DisposableFormatDefinition : ClassificationFormatDefinition
{
public DisposableFormatDefinition()
{
DisplayName = "Disposable Format";
ForegroundColor = Color.FromRgb(0xFF, 0x00, 0x00);
}
}
public event EventHandler<SnapshotSpanEventArgs> TagsChanged = delegate { };
private ITextBuffer _subjectBuffer;
private ClassificationTag _tag;
private IClassifier _classifier;
private bool _reentrant;
public HighlightDisposableTagger(ITextBuffer subjectBuffer, IClassificationTypeRegistryService typeService, IClassifier classifier)
{
_subjectBuffer = subjectBuffer;
var classificationType = typeService.GetClassificationType(DisposableFormatName);
_tag = new ClassificationTag(classificationType);
_classifier = classifier;
}
public IEnumerable<ITagSpan<ClassificationTag>> GetTags(NormalizedSnapshotSpanCollection spans)
{
if (_reentrant) {
return Enumerable.Empty<ITagSpan<ClassificationTag>>();
}
var tags = new List<ITagSpan<ClassificationTag>>();
try {
_reentrant = true;
foreach (var span in spans) {
if (span.IsEmpty)
continue;
foreach (var token in _classifier.GetClassificationSpans(span)) {
if (token.ClassificationType.IsOfType(/*PredefinedClassificationTypeNames.Identifier*/ "User Types")) {
// TODO: Somehow figure out if this refers to a class which implements IDisposable
if (token.Span.GetText() == "Stream") {
tags.Add(new TagSpan<ClassificationTag>(token.Span, _tag));
}
}
}
}
return tags;
}
finally {
_reentrant = false;
}
}
}
I've only tested this on VS2010, but it should work for VS2013 too (the only thing that might be different is the class classification name, but that's easy to discover with a well-placed breakpoint). I've never written an extension for VS2012, so I can't comment on that, but I know it's quite close to VS2013 in most respects.

So, one possible solution(I believe this one works):
1) Create your own content type which inherits from csharp.
2) Create new TextViewCreationListener which will swap out all "csharp" content types with your own one, thus potentially "disarming" all the other classifiers.
3) Register your classifier to handle your own content type.
Here is some of the code:
[Export(typeof(IVsTextViewCreationListener))]
[ContentType("csharp")]
[TextViewRole(PredefinedTextViewRoles.Editable)]
class TextViewCreationListener : IVsTextViewCreationListener {
internal readonly IVsEditorAdaptersFactoryService _adaptersFactory;
[Import] internal IContentTypeRegistryService ContentTypeRegistryService = null;
[ImportingConstructor]
public TextViewCreationListener(IVsEditorAdaptersFactoryService adaptersFactory) {
_adaptersFactory = adaptersFactory;
}
#region IVsTextViewCreationListener Members
public void VsTextViewCreated(VisualStudio.TextManager.Interop.IVsTextView textViewAdapter) {
var textView = _adaptersFactory.GetWpfTextView(textViewAdapter);
var myContent = ContentTypeRegistryService.GetContentType(MyContentType);
if(myContent == null)
{
ContentTypeRegistryService.AddContentType(MyContentType, new[] {"csharp"});
myContent = ContentTypeRegistryService.GetContentType(MyContentType);
}
// some kind of check if the content type is not already MyContentType.
textView.TextBuffer.ChangeContentType(myContent, null);
}
#endregion
}
And now, just modify your IClassifierProvider to register with your own content type, as such: [ContentType(MyContentType)]
Iin your own IClassifier, you can basically do your own calculation and once you think you can't handle the stuff, you could pass the control to other classifiers.
If you use MEF and import IClassifierAggregatorService, you can get a "MASTER-classifier" which will run all the logic for you. I haven't implemented it yet, but I've suggestes something similiar in the past, and it seemed to work. Alternatively you could maybe use [ImportMany] with List<IClassifier> and filter out the csharp ones?!

What does "DisplayClass" name mean when calling lambda?

According to this answer when code uses local variables from inside lambda methods the compiler will generate extra classes that can have name such as c__DisplayClass1. For example the following (completely useless) code:
class Program
{
static void Main()
{
try {
implMain();
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
}
static void implMain()
{
for (int i = 0; i < 10; i++) {
invoke(() => {
Console.WriteLine(i);
throw new InvalidOperationException();
});
}
}
static void invoke(Action what)
{
what();
}
}
outputs the following call stack:
System.InvalidOperationException
at ConsoleApplication1.Program.<>c__DisplayClass2.<implMain>b__0()
at ConsoleApplication1.Program.invoke(Action what)
at ConsoleApplication1.Program.implMain()
at ConsoleApplication1.Program.Main()
Note that there's c__DisplayClass2 in there which is a name of a class generated by the compiler to hold the loop variable.
According to this answer c__DisplayClass "means"
c --> anonymous method closure class ("DisplayClass")
Okay, but what does "DisplayClass" mean here?
What does this generated class "display"? In other words why is it not "MagicClass" or "GeneratedClass" or any other name?

From an answer to a related question by Eric Lippert:
The reason that a closure class is called "DisplayClass" is a bit unfortunate: this is jargon used by the debugger team to describe a class that has special behaviours when displayed in the debugger. Obviously we do not want to display "x" as a field of an impossibly-named class when you are debugging your code; rather, you want it to look like any other local variable. There is special gear in the debugger to handle doing so for this kind of display class. It probably should have been called "ClosureClass" instead, to make it easier to read disassembly.

You can get some insight from the C# compiler source as available from the SSCLI20 distribution, csharp/sccomp subdirectory. Searching the code for "display" gives most hits in the fncbind.cpp source code file. You'll see it used in code symbols as well as comments.
The comments strongly suggest that this was a term used internally by the team, possibly as far back as the design meetings. This is .NET 2.0 vintage code, there was not a lot of code rewriting going on yet. Just iterators and anonymous methods, both implemented in very similar ways. The term "display class" is offset from "user class" in the comments, a clear hint that they used the term to denote auto-generated classes. No strong hint why "display" was favored, I suspect that it might have something to do with these classes being visible in the metadata of the assembly.

Based on Reflector, DisplayClass can be translated as CompilerGeneratedClass
[CompilerGenerated]
private sealed class <>c__DisplayClass16b
{
// Fields
public MainForm <>4__this;
public object sender;
// Methods
public void <cmdADSInit_Click>b__16a()
{
ADS.Initialize();
this.<>4__this._Sender = this.sender;
this.<>4__this.SelectedObject = ADS.Instance;
}
}

Is it safe to use reflection and enums for logic control of MVC application access?

Trying to manage access to a web site I created some necessary entities
The goal is use a custom permission attribute for some controller's action method of my MVC application.
[Permissions(PermissionType.SomePermissionName, CrudType.CanDelete)]
public ActionResult SomeAction()
{
}
For this operation I have two enums
[Flags]
public enum CrudType
{
CanCreate = 0x1,
CanRead = 0x2,
CanUpdate = 0x4,
CanDelete = 0x8,
}
[Flags]
public enum PermissionType
{
SomePermissionName = 0x1,
//...
}
Now I want the method below to check permissions
public static bool CanAccess(RolePermissions rp, CrudType crudType)
{
var pInfo = rp.GetType().GetProperties();
var res = pInfo.FirstOrDefault(x => x.Name == crudType.ToString());
if(res != null)
{
return Convert.ToBoolean(res.GetValue(rp, null));
}
return false;
}
It works good but is it safe to use reflection here? Is it a good style?
One more question is about such piece of code
var permission = PermissionService.GetByName(permissionType.ToString());
Here I'm trying to get a permission object from a database using some named constant from the PermissionType enum.
In both cases the correct work depends on relationships between enums and some table fields or records. On other side I have a good mechanism of controlling logic (as it seems to me).
Is that a good way?

ANOTHER EDIT
In your case it would make sense to create a readonly property ExistingPermissions for the RolePermissions class, and do the merging of the four booleans into one CrudType within that property getter. Then you can just do rp.ExistingPermissions.HasFlag(permissionToCheck).
EDITED
Thanks to #DevDelivery for pointing out the issue - good catch. Unfortunately the fixed solution isn't as pretty as I was hoping for, so in this case it might make sense to go with #DevDelivery's approach.
Since you have your CrudType as "bitfields", you can use a cleaner approach (less code and better readability):
public static bool CanAccess(RolePermissions rp, CrudType permissionToCheck)
{
CrudType existingPermissions =
SetPermissionFlag(CrudType.CanCreate, rp.CanCreate) |
SetPermissionFlag(CrudType.CanRead, rp.CanRead) |
SetPermissionFlag(CrudType.CanUpdate, rp.CanUpdate) |
SetPermissionFlag(CrudType.CanDelete, rp.CanDelete);
return existingPermissions.HasFlag(permissionToCheck);
}
public static CrudType SetPermissionFlag(CrudType crudType, bool permission)
{
return (CrudType)((int)crudType * Convert.ToInt32(permission));
}
The drawback compared to your solution is that you will have to modify this method in case you add more operations (to the existing CanRead, etc.).

Using reflection has a performance impact and the late-binding means that changing a name of a enum
or property will not get caught by the compiler.
Plus, this code is very hard to understand, thus difficult to maintain.
Here there are only 4 options to check. A simple switch statement is easier, faster, and cleaner.
Using reflection would make sense if you were trying to allow for changes to the database or for third-party components to introduce new permissions.

Caching attribute for method?

Maybe this is dreaming, but is it possible to create an attribute that caches the output of a function (say, in HttpRuntime.Cache) and returns the value from the cache instead of actually executing the function when the parameters to the function are the same?
When I say function, I'm talking about any function, whether it fetches data from a DB, whether it adds two integers, or whether it spits out the content of a file. Any function.

Your best bet is Postsharp. I have no idea if they have what you need, but that's certainly worth checking. By the way, make sure to publish the answer here if you find one.
EDIT: also, googling "postsharp caching" gives some links, like this one: Caching with C#, AOP and PostSharp
UPDATE: I recently stumbled upon this article: Introducing Attribute Based Caching. It describes a postsharp-based library on http://cache.codeplex.com/ if you are still looking for a solution.

I have just the same problem - I have multiply expensive methods in my app and it is necessary for me to cache those results. Some time ago I just copy-pasted similar code but then I decided to factor this logic out of my domain.
This is how I did it before:
static List<News> _topNews = null;
static DateTime _topNewsLastUpdateTime = DateTime.MinValue;
const int CacheTime = 5; // In minutes
public IList<News> GetTopNews()
{
if (_topNewsLastUpdateTime.AddMinutes(CacheTime) < DateTime.Now)
{
_topNews = GetList(TopNewsCount);
}
return _topNews;
}
And that is how I can write it now:
public IList<News> GetTopNews()
{
return Cacher.GetFromCache(() => GetList(TopNewsCount));
}
Cacher - is a simple helper class, here it is:
public static class Cacher
{
const int CacheTime = 5; // In minutes
static Dictionary<long, CacheItem> _cachedResults = new Dictionary<long, CacheItem>();
public static T GetFromCache<T>(Func<T> action)
{
long code = action.GetHashCode();
if (!_cachedResults.ContainsKey(code))
{
lock (_cachedResults)
{
if (!_cachedResults.ContainsKey(code))
{
_cachedResults.Add(code, new CacheItem { LastUpdateTime = DateTime.MinValue });
}
}
}
CacheItem item = _cachedResults[code];
if (item.LastUpdateTime.AddMinutes(CacheTime) >= DateTime.Now)
{
return (T)item.Result;
}
T result = action();
_cachedResults[code] = new CacheItem
{
LastUpdateTime = DateTime.Now,
Result = result
};
return result;
}
}
class CacheItem
{
public DateTime LastUpdateTime { get; set; }
public object Result { get; set; }
}
A few words about Cacher. You might notice that I don't use Monitor.Enter() ( lock(...) ) while computing results. It's because copying CacheItem pointer ( return (T)_cachedResults[code].Result; line) is thread safe operation - it is performed by only one stroke. Also it is ok if more than one thread will change this pointer at the same time - they all will be valid.

You could add a dictionary to your class using a comma separated string including the function name as the key, and the result as the value. Then when your functions can check the dictionary for the existence of that value. Save the dictionary in the cache so that it exists for all users.

PostSharp is your one stop shop for this if you want to create a [Cache] attribute (or similar) that you can stick on any method anywhere. Previously when I used PostSharp I could never get past how slow it made my builds (this was back in 2007ish, so this might not be relevant anymore).
An alternate solution is to look into using Render.Partial with ASP.NET MVC in combination with OutputCaching. This is a great solution for serving html for widgets / page regions.
Another solution that would be with MVC would be to implement your [Cache] attribute as an ActionFilterAttribute. This would allow you to take a controller method and tag it to be cached. It would only work for controller methods since the AOP magic only can occur with the ActionFilterAttributes during the MVC pipeline.
Implementing AOP through ActionFilterAttribute has evolved to be the goto solution for my shop.

AFAIK, frankly, no.
But this would be quite an undertaking to implement within the framework in order for it to work generically for everybody in all circumstances, anyway - you could, however, tailor something quite sufficient to needs by simply (where simplicity is relative to needs, obviously) using abstraction, inheritance and the existing ASP.NET Cache.

If you don't need attribute configuration but accept code configuration, maybe MbCache is what you're looking for?

Implementing a CVAR system

I would like to implement what I know as a CVAR System, I'm not entirely sure on what the official name of it is (if any).
It's essentially a system used in some programs and video games, where a user can pull down a console and input a command, such as "variable 500" to set that variable to 500. Instances of this can be found in any Half-Life game, Doom and Quake games, and many more. The general idea seems to be to hide the underlying architecture, but still allow protected access, for instance, one may be able to view the value for, say, gravity, but not change it. Some of these values may also be functions, for instance, a user may be able to input "create " to create an enemy type at their location, or some other location specified.
Looking through the Half Life 2 SDK, and from what I remember on the GoldSrc SDK, it seems like they at least implemented "flagging" of sorts, where certain commands would only work under certain conditions, such as if another value was set, or if the user has some permission level.
My initial thought was to create a Dictionary, or an object similar to do that, and use that to bind string values to function delegates, as well as keep a "protection" level of sorts, to limit usage of certain commands. However, this seems rather cumbersome, as I believe I would have to go through and add in a new entry manually for each value or function I wanted to implement. I also don't know if this would give me the control level I'm looking for.
I believe ideally what I would like would be a CVAR System class, as well as a Register function that can take it say, a variable/function delegate, a string to access it, and whatever protection level I need. This way I can add what I need as I see them, so everything is still in it's related classes and files.
I'm really just looking for some ideas here, so my questions are:
Has anyone ever done something like this before, and if so, how?
Would my implementation work? (Theoretically, if not, can you think of a better way?)
If someone is more knowledgeable with how one of the previously mentioned titles does it, can you elaborate on that a bit? It seems to be hard to find documentation on them.
I'm not really looking for specific code, just more of structuring design. And it doesn't have to be "commercial" or work just like another, I just need something to get me going.

Were you thinking about something like this?
class CVAR
{
[ProtectionLevel(CVARFlags.InGameOnly | CVARFlags.Admin)]
private float gravity = 0.1f;
[ProtectionLevel(CVARFlags.InGameOnly | CVARFlags.Admin)]
private float friction = 0.1f;
[ProtectionLevel(CVARFlags.ReadOnly)]
private string serverVersion = "x.x.x";
public void SetCVARValue(string commandLine) {
string cvarName = GetCvarName(commandLine); // parse the cmd line and get the cvar name from there
object cvarValue = GetCvarValue(commandLine); // parse the value from the string
FieldInfo field = typeof(CVAR).GetField(cvarName);
object[] attributes = field.GetCustomAttributes(typeof(ProtectionLevel), false);
if(attributes.Length > 0) {
ProtectionLevelAttribute attr = (ProtectionLevelAttribute)attributes[0];
if(attr.CheckConditions(World.Instance)) {
field.SetValue(this, cvarValue);
} else {
// error report
}
}
}
}

You could write a parser that looks for commands like
/object_property value
/object_method arg1 arg2
A dictionary, like you suggested, could map those strings to properties and functions. The creation of the dictionary could be done dynamically using reflection by looping through eligible objects, taking their public methods and accessors, and generating a string for them.
Then the dictionary could be mapped in a class for convenience and error checking.
For the methods, the dictionary values could be delegates that take 0..n arguments, for the properties/fields, you will need to be able to some data binding between your actual fields and the dictionary value. UNLESS, your objects themselves refer to the dictionaries for their values, in which case the values only live in place.
To do so, you could simply register your properties using reflection in the object constructor, then call the dictionary in your properties.
[Flags]
public enum CVarAccessibilities
{
Settable,
Gettable
}
public class CVar<T>
{
public CVarAccessibilities Accessibility { get; set; }
T val;
public T Value {
get { return val; }
set
{
if (!Accessibility.HasFlag(CVarAccessibilities.Settable))
return; // just don't set it, maybe print some warning
val = value;
}
}
}
public static class CVarRegistry
{
static Dictionary<string, Object> CVars;
static CVarRegistry { /* use reflections to initialize the dictionary */ }
public static T GetValue<T>(Type owner, string paramName)
{
CVar cvar;
if (!CVars.TryGetValue(owner.Name + "_" + paramName, out cvar)
throw new MyCustomException();
return (T)cvar.Value;
}
public static void SetValue<T>(Type owner, string paramName, T value)
{
CVar cvar;
if (!CVars.TryGetValue(owner.Name + "_" + paramName, out cvar)
throw new MyCustomException();
cvar.Value = value;
}
}
public class MyObject
{
public static int MyRegisteredValue
{
get { return Global.CVarRegistry.GetValue<int>(typeof(MyObject), "MyRegisteredValue"); }
set { Global.CVarRegistry.SetValue(typeof(MyObject), "MyRegisteredValue"); }
}
}
Hope that helps!

This is more commonly known as 'tweak' variables.
Good discussion here: https://gamedev.stackexchange.com/questions/3631/tweaking-and-settings-runtime-variable-modification-and-persistence