Joe Hummel, PhD

@joehummeljoe@joehummel.net

http://www.joehummel.net/downloads.html

Project Roslyn:the compiler is at your service

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2Project Roslyn

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

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3Project Roslyn

Demo!

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What is Project Roslyn?

The ".NET Compiler Platform" Replacement of existing .NET compilers with new ones

csc for C# vbc for VB.NET

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class C{ . . .}

class C{ . . .}

class C{ . . .}

000101010101010101010101010

csc

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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

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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

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Status preview release open source! http://roslyn.codeplex.com

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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

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Before Roslyn…

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C# and VB compilers were black boxes predefined switches only way to interact…

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csc

> csc.exe main.cs /o /warn:4

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After Roslyn…

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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!

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cscRoslyn

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csc

"Call me every time you see an identifier…" (because I'm renaming all global variables)

"Emit this code instead…" (I'm targeting specific HW)

// translate resource strings:foreach(Project p) foreach(Document d) foreach(Resource r) replace(r, r');

Roslyn

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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 …

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?

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Compiler Basics…

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Front-end vs. Back-end Front-end deals with syntax ― "grammar"

Back-end deals with semantics ― "meaning"

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Sourcelanguage

Parsing

Assemblylanguage

Lexical Analysis Compiler

Semantic Analysis

High-level Optimizer Code Gen

Low-level Optimizer

tokens

IR IR' IR''

IR'''

// commentif (x>100) x = 100;

if, (, x, >, 100, ), x, =, …

Typical Compiler Phases

lexical analysisparsing

semantic analysisHL optimizer

code genLL optimizer

syntaxerrors

semanticerrors

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Roslyn Intermediate Representation (IR) Abstract Syntax Tree (AST)

Symbol Table

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+

GCD program

0 "int", type, …

1 "void", type, …

2 …

3 "getint", funct, type: 0, …

4 "putint", funct, type: 1, …

5 "i", var, type: 0, …

6 "j", var, type: 0, …

… …

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How to learn Roslyn AST? Use the Roslyn Syntax Visualizer!

Open a project Open a source file View menu…

>> Other Windows >> Roslyn Syntax Visualizer

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Working with Roslyn…

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Roslyn is BIG There are many APIs… There is the source code itself…

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+

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Start small Let’s create a simple diagnostic that warns

about empty catch blocks…

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Step 1: Create new project…

>> Roslyn >> Diagnostic with Code Fix

Name >> EmptyCatchDiagnostic

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Step 2: Create Syntax Node Analyzer

to detect empty catches

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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, ...){

var catchBlock = node as CatchClauseSyntax;

if (catchBlock.Block.Statements.Count == 0) // empty!{

var diagnostic = Diagnostic.Create(...); // create warning:

addDiagnostic(diagnostic); // display:}

}

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Step 3: Create Code Fix Provider

to optionally correct problem…

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internal class CodeFixProvider : ICodeFixProvider{

.

.

// only called for things of interest:public async Task<…> GetFixesAsync(Document document, ...){

var root = await document.GetSyntaxRootAsync(cancellationToken);

var token = root.FindToken(span.Start); // catch keyword:

if (!token.IsKind(SyntaxKind.CatchKeyword)) // sanity check:return null;

var catchBlock = (CatchClauseSyntax)token.Parent;var throwStmt = SyntaxFactory.ThrowStatement();var newStmts = new

SyntaxList<StatementSyntax>().Add(throwStmt);var newBlock =

SyntaxFactory.Block().WithStatements(newStmts);var newCatchBlock = SyntaxFactory.CatchClause().

WithBlock(newBlock).WithAdditionalAnnotations(Formatter.Annotation);

var newRoot = root.ReplaceNode(catchBlock, newCatchBlock);

return new[] { CodeAction.Create("throw", document.WithSyntaxRoot(newRoot)) };

}

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

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Installing & Using Roslyn…

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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"

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Download "End User Preview / SDK Preview"1. http://msdn.microsoft.com/en-gb/roslyn2. Get the Preview

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Unzip SDK Install:

1. End User Preview2. Project Templates3. Syntax Visualizer4. Roslyn Experimental Hive

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Install Microsoft Visual Studio 2013 SDK

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Summary…

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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

Chicago Code Camp 2014