Roslyn Scripting API Layers

Roslyn consists of two main layers of APIs.

• Compiler APIs
• Workspaces APIs

Compiler APIs

The compiler layer contains the object models that correspond with information exposed at each phase of the compiler pipeline.

• It contains an immutable snapshot of a single invocation of a compiler, including assembly references, compiler options, and source code files.
• There are two distinct APIs that represent the C# language and the Visual Basic language.
• These two APIs are similar in shape but tailored for high-fidelity to each language.
• This layer has no dependencies on Visual Studio components.

Corresponding to each of those phases, an object model is surfaced that allows access to the information at that phase.

• The parsing phase is exposed as a syntax tree.
• The declaration phase is a hierarchical symbol table.
• The binding phase as a model that exposes the result of the compiler's semantic analysis
• The emit phase is an API that produces IL byte codes.

Diagnostic APIs

The compiler may produce a set of diagnostics covering everything from syntax, semantic, and definite assignment errors to various warnings and informational diagnostics.

Scripting APIs

As a part of the compiler layer, the hosting/scripting APIs are created for executing code snippets and accumulating a runtime execution context.

Workspaces APIs

The Workspaces layer contains the Workspace API, which is the starting point for doing code analysis and refactoring over entire solutions.

• It assists you in organizing all the information about the projects in a solution into a single object model, offering you direct access to the compiler layer object models without needing to parse files, configure options or manage a project to project dependencies.
• In addition, the Workspaces layer surfaces a set of commonly used APIs used when implementing code analysis and refactoring tools that function within a host environment like the Visual Studio IDE, such as the Find All References, Formatting, and Code Generation APIs.
• This layer has no dependencies on Visual Studio components.