Develop Reference

How to use language’s parser to get the tokens to populate the completion list in VS SDK?

[Environment]：VS2017+C#
I want to extend Intellisense, just reorder completion list.
I read this doc:Walkthrough: Displaying Statement Completion
Doc say:
The completion source is responsible for collecting the set of identifiers and adding the content to the completion window when a user types a completion trigger, such as the first letters of an identifier. In this example, the identifiers and their descriptions are hard-coded in the AugmentCompletionSession method. In most real-world uses, you would use your language’s parser to get the tokens to populate the completion list.
void ICompletionSource.AugmentCompletionSession(ICompletionSession session, IList<CompletionSet> completionSets)
{
List<string> strList = new List<string>();
strList.Add("addition"); // ☹HARD CODED !!!
strList.Add("adaptation");
strList.Add("subtraction");
strList.Add("summation");
m_compList = new List<Completion>();
foreach (string str in strList)
m_compList.Add(new Completion(str, str, str, null, null));
completionSets.Add(new CompletionSet(
"Tokens", //the non-localized title of the tab
"Tokens", //the display title of the tab
FindTokenSpanAtPosition(session.GetTriggerPoint(m_textBuffer),
session),
m_compList,
null));
} }
So, how to use language’s parser to get the tokens to populate the completion list? I need get default completion list then reorder it.

I think the document is trying to say that that they've hard-coded the list of tokens to make the example easier to understand and that in real life you would have to do something much more complicated.
Exactly what you would have to do would depend on many things including what language you were trying to process. For example, if you were trying to extend Intellisense for C# or Visual Basic you might use Roslyn to parse the source in your project as a way of creating a list of tokens you could use to build the completion list.
If you were working with some other language you would have to find (or create) a tool that could parse the language you were working with.

Parsing C# code for contextually aware semantic highlighting

I'm working on a semantic highlighting plugin for VS. Here you can see a web Example.
The goal:
Acquiring all variables and creating different Classifications for every one of them.
The problem:
Getting the variables from the code without writing a C# lexer.
My current approach uses an ITagger. I use an ITagAggregator to get the tags of all the spans that get passed to the ITagger. Then I filter those and get only spans with the "identifier" classification which includes varibles, methods names, class names, usings and properties.
public class Classifier : ITagger<ClassificationTag> {
public IEnumerable<ITagSpan<ClassificationTag>> GetTags(NormalizedSnapshotSpanCollection spans) {
ITextSnapshot snapshot = spans[0].Snapshot;
var tags = _aggregator.GetTags(spans).Where((span) => span.Tag.ClassificationType.Classification.Equals("identifier")).ToArray();
foreach(var classifiedSpan in tags) {
foreach(SnapshotSpan span in classifiedSpan.Span.GetSpans(snapshot)) {
//generate classification based on variable name
yield return new TagSpan<ClassificationTag>(span, new ClassificationTag(_classification));
}
}
}
}
It would be a lot easier to use the builtin C# Lexer to get a list of all variables bundled to a bunch of meta data. Is this data available for plugin development? Is there an alternative way I could acquire it, if not?

The problem: Getting the variables from the code without writing a C# lexer.
Roslyn can do this: https://roslyn.codeplex.com/
There's even a Syntax Visualizer sample that might interest you. I also found an example using Roslyn to create a Syntax Highlighter.

Visual Studio exposes that information as a code model.
Here is an example how you can access class, and then find attribute on the class, and parse attribute arguments:
Accessing attribute info from DTE
Here is more information about code models:
http://msdn.microsoft.com/en-us/library/ms228763.aspx
Here's also automation object model chart what I've been using quite few times: http://msdn.microsoft.com/en-us/library/za2b25t3.aspx
Also, as said, Roslyn is indeed also a possible option. Here is an example for VS2015 using roslyn: https://github.com/tomasr/roslyn-colorizer/blob/master/RoslynColorizer/RoslynColorizer.cs

For building language tools if may be better to use a parser generator for C#. The GOLD parsing system is one such toolkit which can handle LALR grammars. It has a .NET component based engine that you can use in your project and it can be used to integrate with any IDE. You can also find the grammars for various programming languages including C#.

Templated Lists in C#?

I know templates are common within c/c++ however I am currently trying to translate an old VB code our company uses up to a c# equivalent which brings me to my problem....
VB is an type unsafe language so we come across things like
Public Elements As New Collection
so given the line above I need to translate that to a List.. Given that a Collection can be anything from a List to a map I need to template this as efficiently as possible. I was thinking of for first draft ignoring the map option entirely and just making it a List however from my understanding Templates don't truly exist within C#... The below code is what I came up with so far and while it compiles (I have not gotten to a testing point in the rest of the code yet) I don't know if it would actually work...
Public List<ValueType> Elements = new List<ValueType>();
can anyone offer input on if this would work as a generic list where type is determined at input or if I need to change this so the constructor would look more like
Public List<ValueType> Elements = new List<typeof(foo)>();
if the above is confusing I am sorry it is for me as well, and I will try and clarify as questions come in.
this question is no longer relevant, I was able to go into the source of the calling code and determine what variable types that the lists need to support.

Is it possible to use a LINQ Query in Windows Workflow rule condition?

I am in the process of prototyping an implementation of a rules engine to help us with our ordering portals. For example giving discounts on items or requiring approval if certain items are ordered. We would also like to be able to add rules for dollar amounts, user hierarchy positions, and be apply it one client or more.
I feel that WWF is a good answer to this need.
All of that said however I am having a little difficulty figuring out how best to set up some of the more complex rules. I have a "condition" that I feel is best described in a LINQ query, like so:
var y = from ol in currentOrder.OrderLines where ol.ItemCode == "MYITEMCODE" select ol;
I am not against using a different framework for a rules engine or adding additional properties/methods to our objects (ex: OrderHasItem(ItemCode), etc) to make these rules more simplified but I would like to avoid having to do that. It feels self-defeating in that it forces us down the road of potentially requiring code changes for new rules.

Yes, you can use Linq queries with Workflow. In WF what you are referring to as a rule is an expression that is evaluated at runtime. Your query is selecting a subset of the orderliness based on a criteria.
For example, if I have a collection of names and I want to see only names that begin with 'R'. I could write the following code.
private static void ShowQueryWithCode(IEnumerable<string> names)
{
Console.WriteLine("LINQ Query in Code - show names that start with 'R'");
// Assuming there are no null entries in the names collection
var query = from name in names where name.StartsWith("R") select name;
// This is the same thing as
// var query = names.Where(name => name.StartsWith("R"));
foreach (var name in query)
{
Console.WriteLine(name);
}
Console.WriteLine();
}
To do the same with Workflow
Step 1: Create a Workflow with an In Argument of type IEnumerable
Here you can see that I've added the in argument
Step 2: Add a Variable for the query of type IEnumerable
Before you can add a variable you need to include an activity which has variables. In this workflow I've added a sequence.
Step 3: Assign the query the LINQ expression you want to use
You can use a method chain or query syntax.
Step 4: Iterate over the collection
In the completed workflow I used a ForEach activity to iterate the list of names and write them to the console.
This example uses C# in .NET 4.5 but the same technique can be used with Visual Basic.
You can download the sample code here

WF is a workflow engine. It's used to run factories and banks. The rule engine is just a small part of it. To make sense, any normal WF project requires a dedicated team of professionals to build it. Seems like an overkill for your specific purpose. You are very likely to bury yourself and your project in a typical fight between requirements and real skills of your team.
The use of any available .NET engine would be more justified in your situation. Keep in mind that building a custom rule engine is not an easy tasks, no matter how simple it seems from the beginning. Setting property values of a class (typically called a "fact" or "source" object) or executing actions (invoking class' methods) is what rules engines do best. And it seems that it's exactly what you need. Check out some available .NET engines. They are inexpensive, if not free, and reliable.

Dynamic "WHERE" like queries on memory objects

What would be the best approach to allow users to define a WHERE-like constraints on objects which are defined like this:
Collection<object[]> data
Collection<string> columnNames
where object[] is a single row.
I was thinking about dynamically creating a strong-typed wrapper and just using Dynamic LINQ but maybe there is a simpler solution?
DataSet's are not really an option since the collections are rather huge (40,000+ records) and I don't want to create DataTable and populate it every time I run a query.

What kind of queries do you need to run? If it's just equality, that's relatively easy:
public static IEnumerable<object[]> WhereEqual(
this IEnumerable<object[]> source,
Collection<string> columnNames,
string column,
object value)
{
int columnIndex = columnNames.IndexOf(column);
if (columnIndex == -1)
{
throw new ArgumentException();
}
return source.Where(row => Object.Equals(row[columnIndex], value);
}
If you need something more complicated, please give us an example of what you'd like to be able to write.

If I get your point : you'd like to support users writting the where clause externally - I mean users are real users and not developers so you seek solution for the uicontrol, code where condition bridge. I just though this because you mentioned dlinq.
So if I'm correct what you want to do is really :
give the user the ability to use column names
give the ability to describe a bool function (which will serve as where criteria)
compose the query dynamically and run
For this task let me propose : Rules from the System.Workflow.Activities.Rules namespace. For rules there're several designers available not to mention the ones shipped with Visual Studio (for the web that's another question, but there're several ones for that too).I'd start with Rules without workflow then examine examples from msdn. It's a very flexible and customizable engine.
One other thing: LINQ has connection to this problem as a function returning IQueryable can defer query execution, you can previously define a query and in another part of the code one can extend the returned queryable based on the user's condition (which then can be sticked with extension methods).

When just using object, LINQ isn't really going to help you very much... is it worth the pain? And Dynamic LINQ is certainly overkill. What is the expected way of using this? I can think of a few ways of adding basic Where operations.... but I'm not sure how helpful it would be.

How about embedding something like IronPython in your project? We use that to allow users to define their own expressions (filters and otherwise) inside a sandbox.

I'm thinking about something like this:
((col1 = "abc") or (col2 = "xyz")) and (col3 = "123")
Ultimately it would be nice to have support for LIKE operator with % wildcard.

Thank you all guys - I've finally found it. It's called NQuery and it's available from CodePlex. In its documentation there is even an example which contains a binding to my very structure - list of column names + list of object[]. Plus fully functional SQL query engine.
Just perfect.