LINQPad.CodeAnalysis

Because it is so low ceremony but also has advanced functionality like debugging, data source connections, and advanced output and visualization, LINQPad provides an ideal platform for quickly experimenting, exploring, and working with the .NET Compiler Platform. This library adds various capabilities to LINQPad that make working with the .NET Compiler Platform easier.

LINQPad 5

Most of the functionality in LINQPad.CodeAnalysis can now be found in LINQPad 5 (as of 5.02 beta). When using LINQPad 5, the syntax tree and syntax visualizer are both found under the "Tree" tab after executing a query. This tab is available for any query and you can also dump a SyntaxTree or SyntaxNode explicitly by calling .DumpSyntaxTree() or .DumpSyntaxNode(). The integration in LINQPad 5 is also tighter than a plugin allows and lets you highlight the original query as you highlight nodes in the syntax tree as well as other UI improvements. I'd like to thank Joseph Albahari for making this integration possible and for tweaking things to provide the best possible experience.

Unless you're using an older version of LINQPad (such as one of the version 4 betas 4.56.04 or higher) or want access to semantic information from the syntax tree (which isn't included in the new integration), I recommend relying on the integrated native to LINQPad.

Installation

Please note that at this time, LINQPad.CodeAnalysis requires LINQPad version 4.56.04 or better, which is a beta release.

Install via NuGet

If you want to use LINQPad.CodeAnalysis on a query-by-query basis, it can be installed via NuGet:

• Open the LINQPad NuGet Manager
  • Right-click your query and select Query Properties...
  • Select Add NuGet...
• Perform a search for LINQPad.CodeAnalysis
  • Note that the LINQPad.CodeAnalysis package is prerelease because the Microsoft.CodeAnalysis packages on which it depends are also prerelease.
• Install it to the LINQPad NuGet cache and add it to your query by selecting Add To Query
• The capabilities of LINQPad.CodeAnalysis will now be available to your query.

Note that NuGet support is only available in LINQPad Developer and LINQPad Premium editions.

Install as a Plugin

LINQPad also supports plugins, which are typically installed to My Documents\LINQPad Plugins. To install LINQPad.CodeAnalysis as a plugin and make it available to any query from your installation of LINQPad:

• Download the latest release as a .zip file from the GitHub Releases at https://github.com/somedave/LINQPad.CodeAnalysis/releases
• Unzip the archive into your My Documents\LINQPad Plugins folder.

Syntax Tree

The first feature is a syntax tree visualizer similar to the one available for Visual Studio 2015. It allows you to dump a syntax tree for your current query, other queries, or generated directly via the .NET Compiler Platform.

Note that the syntax tree output tab is not automatic like the IL or SQL LINQPad output tabs. You must use one of the techniques below to display the syntax tree on-demand for each query.

From Your Query

Dumping a .NET Compiler Platform syntax tree from your current query is easy. Use CodeAnalysisUtil.DumpSyntaxTree() inside your query. This will get the text of the currently executing query, generate an appropriate .NET Compiler Platform SyntaxTree, and dump it to an output tab.

From Another Query

You can output a syntax tree from any other query as well (for example, a query returned by a call to Util.GetMyQueries()). Use the static method CodeAnalysisUtil.DumpSyntaxTree(query) or the extension method query.DumpSyntaxTree().

From a SyntaxTree

If you construct a SyntaxTree directly by using the .NET Compiler Platform, it can also be dumped to an output tab. Use the static method CodeAnalysisUtil.DumpSyntaxTree(syntaxTree) or the extension method syntaxTree.DumpSyntaxTree().

Dumping a Syntax Tree Node

The syntax tree visualization shows all of the nodes in the syntax tree. Double-clicking on one of the nodes will result in that node being dumped as a class in a seperate output tab. This makes it very easy to explore the various properties of the nodes in the syntax tree.

Filtering by Node Type

The syntax tree shows SyntaxNode nodes (in blue), SyntaxToken nodes (in green), and SyntaxTrivia nodes (in maroon). Because they sometimes add noise when you're looking for specific patterns or syntax, you can toggle filtering out SyntaxToken nodes, SyntaxTrivia nodes, or both. To do so, click the check boxes next to these node types in the syntax tree tool bar.

Declaration Filter

It may be difficult to find the exact syntax tree node you're looking for (be it a class, method, property, etc.) Decalaration filtering allows you to limit the syntax tree to just those nodes that represent a declaration with a given name. For example, consider the following code.

public class A
{
  public int X { get; set; }
}

public class B
{
  public int Y { get; set; }
  public int A { get; set; }
}

If you set a declaration filter of B, the syntax tree will contain the node for class B. If you set a declaration filter of A, the syntax tree will contain two root nodes, one for class A and another for property B.A.

This can be useful when you want to isolate the syntax tree for a particular portion of your query. For example, you may put the bit that you care about in a seperate method and then set a declaration filter that only outputs the syntax tree for that method.

All of the DumpSyntaxTree() methods accept an initial declaration filter. You can also specify one within the interface in the tool bar.

What's Next?

To a large extent, that's up to you! If you have any ideas for helpful tools to make working with the .NET Compiler Platform from LINQPad easier, just let me know by opening a new issue. Some ideas I have:

• Even more syntax tree functionality such as round-trip code review and graph visualization.
• Some kind of support for writing and/or applying diagnostics and code fixes.
• Support for the new .NET Compiler Platform scripting capabilities (such as outputting code that packages a LINQPad query as a script).