Project Roslyn:

1. Project Roslyn: the compiler is at your service Joe Hummel, PhD @joehummel joe@joehummel.net http://www.joehummel.net/downloads.html Chicago Code Camp 2014

2. Joe Hummel, PhD • Professor: U. of Illinois, Chicago • Consultant: Joe Hummel, Inc. • Trainer: Pluralsight • Microsoft MVP C++ • Chicago-based, one daughter adopted from China (now 12!) • Avid sailor Project Roslyn

3. Demo! Project Roslyn

4. What is Project Roslyn? • The ".NET Compiler Platform" • Replacement of existing .NET compilers with new ones • csc for C# • vbc for VB.NET class C { . . . } class C { . . . } class C { . . . } csc 000101010101010101010101010 Project Roslyn

5. Why is this a big deal? • Risky • if they get this wrong, folks can't build their apps • if they get this wrong, MSFT can't build their apps Project Roslyn

6. What's the benefit? • Faster turnaround on new features • inside and outside MSFT • Grow the Visual Studio ecosystem • MUCH easier to build new tools • MUCH easier to extend Visual Studio, C# and VB • MUCH easier to try out new ideas Project Roslyn

7. Status • preview release • open source! • http://roslyn.codeplex.com Project Roslyn

8. Open source? • Yes, open source! • Apache license 2.0 • You are free to GIT, fork, modify, rebuild, deploy • Anders did this on stage @ Build 2014 Project Roslyn

9. Before Roslyn… Project Roslyn

10. C# and VB compilers were black boxes • predefined switches only way to interact… > csc.exe main.cs /o /warn:4 csc Project Roslyn

11. After Roslyn… Project Roslyn

12. The compilers are now white boxes • You can: • obtain information about a program • modify a program syntactically / semantically • impact the compilation process • change the compiler itself! Roslyn csc Project Roslyn

13. "Call me every time you see an identifier…" (because I'm renaming all global variables) "Emit this code instead…" (I'm targeting specific HW) Roslyn // translate resource strings: foreach(Project p) foreach(Document d) foreach(Resource r) replace(r, r'); csc Project Roslyn

14. ? • What can we do with this capability? • Infinite possibilities: • better tools — refactoring, analysis, … • better enforcement of coding standards • add scripting support to your app • target new platforms • language research — DSLs, … • compiler research • … Project Roslyn

15. Compiler Basics… Project Roslyn

16. Front-end vs. Back-end • Front-end deals with syntax ― "grammar" • Back-end deals with semantics ― "meaning" Project Roslyn

17. // comment if (x>100) x = 100; Typical Compiler Phaseslexical analysisparsingsemantic analysisHL optimizercode genLL optimizer Sourcelanguage Lexical Analysis Compiler tokens if, (, x, >, 100, ), x, =, … IR IR' IR'' Parsing Semantic Analysis High-level Optimizer Code Gen IR''' Low-level Optimizer syntaxerrors semanticerrors Assemblylanguage Project Roslyn

18. Roslyn Intermediate Representation (IR) • Abstract Syntax Tree (AST) • Symbol Table + GCD program Project Roslyn

19. How to learn Roslyn AST? • Use the Roslyn Syntax Visualizer! • Open a project • Open a source file • View menu… >> Other Windows >> Roslyn Syntax Visualizer Project Roslyn

20. Working with Roslyn… Project Roslyn

21. Roslyn is BIG • There are many APIs… • There is the source code itself… + Project Roslyn

22. Start small  • Let’s create a simple diagnostic that warns about empty catch blocks… Project Roslyn

23. Step 1: • Create new project… >> Roslyn >> Diagnostic with Code Fix • Name >> EmptyCatchDiagnostic Project Roslyn

24. public class DiagnosticAnalyzer: ISyntaxNodeAnalyzer<SyntaxKind> { . . . public ImmutableArray<SyntaxKind> SyntaxKindsOfInterest { get { return ImmutableArray.Create( SyntaxKind.CatchClause); } } // only called for things of interest: public void AnalyzeNode(SyntaxNode node, ...) { varcatchBlock = node as CatchClauseSyntax; if (catchBlock.Block.Statements.Count== 0) // empty! { vardiagnostic = Diagnostic.Create(...); // create warning: addDiagnostic(diagnostic); // display: } } • Step 2: • Create Syntax Node Analyzer to detect empty catches Project Roslyn

25. internal class CodeFixProvider: ICodeFixProvider { . . // only called for things of interest: public async Task<…> GetFixesAsync(Document document, ...) { varroot = await document.GetSyntaxRootAsync(cancellationToken); vartoken = root.FindToken(span.Start); // catch keyword: if (!token.IsKind(SyntaxKind.CatchKeyword)) // sanity check: return null; varcatchBlock= (CatchClauseSyntax)token.Parent; varthrowStmt = SyntaxFactory.ThrowStatement(); varnewStmts= new SyntaxList<StatementSyntax>().Add(throwStmt); varnewBlock= SyntaxFactory.Block().WithStatements(newStmts); varnewCatchBlock= SyntaxFactory.CatchClause().WithBlock(newBlock). WithAdditionalAnnotations(Formatter.Annotation); varnewRoot= root.ReplaceNode(catchBlock, newCatchBlock); return new[] { CodeAction.Create("throw", document.WithSyntaxRoot(newRoot)) }; } • Step 3: • Create Code Fix Provider to optionally correct problem… Project Roslyn

26. Step 4: • Run! • A .vsix installer is built • A new instance of VS is started • The .vsix is installed • Open a project and test… Project Roslyn

27. Installing & Using Roslyn… Project Roslyn

28. Caveats! • You will be *replacing* your C# and VB compilers • Are you sure? • Scripting support is currently missing • i.e. using Roslyn to add C# / VB scripting to your app • MSFT is "re-evaluating design" Project Roslyn

29. Download "End User Preview / SDK Preview" • http://msdn.microsoft.com/en-gb/roslyn • Get the Preview Project Roslyn

30. Unzip SDK • Install: • End User Preview • Project Templates • Syntax Visualizer • Roslyn Experimental Hive Project Roslyn

31. Install Microsoft Visual Studio 2013 SDK Project Roslyn

32. Summary… Project Roslyn

33. Thank you for attending! • Joe Hummel, PhD • Email: joe@joehummel.net • Materials: http://www.joehummel.net/downloads.html • For more information on Roslyn: • Docs / FAQ: • http://roslyn.codeplex.com/documentation • Build 2014 on Channel 9 • The Future of C# • https://channel9.msdn.com/Events/Build/2014/2-577 Project Roslyn