Language-Agnostic Code Generation with Roslyn

摘要

The Roslyn code base provides powerful APIs you can leverage to perform rich code analysis over your source code. For instance, analyzers and code refactorings can walk through a piece of source code and replace one or more syntax nodes with new code you generate with the Roslyn APIs. A common way to perform code generation is via the SyntaxFactory class, which exposes factory methods to generate syntax nodes in a way that compilers can understand. The SyntaxFactory class is certainly very powerful because it allows generating any possible syntax element, but there are two different SyntaxFactory implementations: MicrosoftCodeAnalysis.CSharp.SyntaxFactoryandMicrosoft.Code-Analysis.VisualBasic.SyntaxFactory. This has an important implication if you want to write an analyzer with a code fix that targets both C# and Visual Basic-you have to write two different analyzers, one for C# and one for Visual Basic, using the two implementations of SyntaxFactory, each with a different approach due to the different way those languages handle some constructs. This likely means wasting time writing the analyzer twice, and maintaining them becomes more difficult. Fortunately, the Roslyn APIs also provide the MicrosoftCodeAnalysis.Editing.SyntaxGenerator, which allows for language-agnostic code generation. In other words, with Syntax-Generator you can write your code-generation logic once and target both C# and Visual Basic. In this article I'll show you how to perform language-agnostic code generation with SyntaxGenerator, and I'll give you some hints about the Roslyn Workspaces APIs.