ReSharper DevGuide

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Get a Tree Node by Full CLR Name

What you should know beforehand:

Examples (?):

Typically, finding a node by a full CLR name is not a typical type of task for a plugin developer. This example is given mostly to help you better understand ReSharper’s project model and PSI principles.

Let’s imagine, you know a full CLR name of a class and want to navigate to it. See the example below.

  1. First of all, we need to obtain an IProject instance for a particular project (by project’s name). Here we work on the ReSharper’s project model level. Let’s make it an extension method of ISolution:

    [CanBeNull] public static IProject GetProjectByName(this ISolution solution, string projectName) { var projects = solution.GetTopLevelProjects(); return projects.FirstOrDefault(project => project.Name == projectName); }

    Here GetTopLevelProjects() returns a collection of projects in the solution.

  2. Knowing the project, we can obtain a particular C# file from it (we’re still on the project model level).

    [CanBeNull] public static ICSharpFile GetCSharpFile(this IProject project, string filename) { var file = project.GetPsiSourceFileInProject(FileSystemPath.Parse(filename)); return file?.GetPsiFiles<CSharpLanguage>().SafeOfType<ICSharpFile>().SingleOrDefault(); }


    • GetPsiSourcFileInProject returns the IPsiSourceFile by file name.
    • GetPsiFiles returns the collection of IFile (the main PSI element) that is then casted to ICSharpFile (SafeOfType is a safer sibling of Enumerable.OfType<>()).
  3. On this step we work only with the PSI syntax tree (so, now, we’re on the PSI model level). Here we obtain an instance of ICSharpFile and find the required ITreeNode in it.

    [CanBeNull] public static ITreeNode GetTypeTreeNodeByFqn(this ICSharpFile file, string typeName) { var namespaceName = GetLongNameFromFqn(typeName); var shortName = GetShortNameFromFqn(typeName); var namespaceDecls = file.NamespaceDeclarationsEnumerable; var namespaceDecl = (from decl in namespaceDecls where decl.DeclaredName == namespaceName select decl).FirstOrDefault(); if (namespaceDecl == null) return null; var typeDecls = namespaceDecl.TypeDeclarationsEnumerable; var resultList = (from node in typeDecls where node.DeclaredName == shortName select node).ToList(); return resultList.FirstOrDefault(); } private static string GetShortNameFromFqn(string fqn) { var pos = fqn.LastIndexOf(".", StringComparison.Ordinal) + 1; return pos > 0 ? fqn.Substring(pos) : fqn; } private static string GetLongNameFromFqn(string fqn) { var pos = fqn.LastIndexOf(".", StringComparison.Ordinal) + 1; return pos > 0 ? fqn.Substring(0, pos - 1) : fqn; }


    • GetShortNameFromFqn and GetLongNameFromFqn are used to get namespace name and type’s short name. Note that these functions are far from optimal (e.g., they do not take into account nested types).
    • NamespaceDeclarationsEnumerable returns a special enumerable type that allows to get all namespaces in a file.
    • TypeDeclarationsEnumerable returns all type declarations made within a namespace.
    • ICSharpTypeDeclaration provides the DeclaredName property that returns type’s short name.
  4. Finally, we can use our GetTypeTreeNodeByFqn function to navigate to the type declaration by knowing type’s fully qualified name:

    public static void NavigateToTypeNodeByFqn(this ISolution solution, string projectName, string fileName, string typeName) { solution.Locks.TryExecuteWithReadLock(() => { var project = solution.GetProjectByName(projectName); var file = project.GetCSharpFile(fileName); var node = file.GetTypeTreeNodeByFqn(typeName); node.NavigateToTreeNode(true); }); }


    • Note that to prevent conflicts with user input, we must obtain the read lock before calculating the node under the caret. Here this is done by means of the special method of the IShellLocks interface: TryExecuteWithReadLock(...). The main difference comparing to the QueueReadLock method used in other examples is that is executed synchronously - as you can see, there’s no Lifetime instance passed to the method.
Last modified: 12 July 2017