IMSBuildGlob should have a method that expands globs · dotnet/msbuild#1908

2017-03-24T20:25:17.000Z

[IMSBuildGlob](https://github.com/Microsoft/msbuild/blob/master/src/Build/Globbing/IMSBuildGlob.cs) currently knows how to match strings against itself. It would be nice if it also had an `ExpandToFiles` method which hit the disk and expanded the glob into matching files, with the same behaviour that the engine is internally using. We didn't expose this functionality because there's no outside asks for it yet. Implementation details: - Since expansion is slow, the results should be cached, and maybe the method should also have an async counterpart - A very easy implementation is to just call `EngineFileUtilities.GetFileList`. However, that method needlessly parses the glob again. A better implementation is to rework the internal static methods to also accept an already parsed glob. This poses some complications due to the different validation checks done by `EngineFileUtilities.GetFileList` and `FileMatcher.GetFiles` - Behaviour on illegal filespecs (as per the engine today): - `EngineFileUtilities.GetFileList` returns back the original illegal filespec - `FileMatcher.GetFiles` return back the original illegal filespec if it's not excluded, otherwise returns empty

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Feature - Globbinghelp wantedtriaged

Description

IMSBuildGlob currently knows how to match strings against itself. It would be nice if it also had an ExpandToFiles method which hit the disk and expanded the glob into matching files, with the same behaviour that the engine is internally using. We didn't expose this functionality because there's no outside asks for it yet.

Implementation details:

Since expansion is slow, the results should be cached, and maybe the method should also have an async counterpart
A very easy implementation is to just call EngineFileUtilities.GetFileList. However, that method needlessly parses the glob again. A better implementation is to rework the internal static methods to also accept an already parsed glob. This poses some complications due to the different validation checks done by EngineFileUtilities.GetFileList and FileMatcher.GetFiles
Behaviour on illegal filespecs (as per the engine today):
- EngineFileUtilities.GetFileList returns back the original illegal filespec
- FileMatcher.GetFiles return back the original illegal filespec if it's not excluded, otherwise returns empty

Contributor guide

Tech stack: csharp
Domain: build systemtooling
Issue type: feature
Difficulty: 3
Estimated time: half day
Activity status: stale
Clarity: clear
Prerequisites: C#MSBuild internals
Newbie friendliness: 40
Research direction: The issue requests adding an ExpandToFiles method to IMSBuildGlob (src/Build/Globbing/IMSBuildGlob.cs). A naive implementation could call EngineFileUtilities.GetFileList, but a better approach is to refactor internal methods to accept an already parsed glob. Investigate the differences in validation between EngineFileUtilities.GetFileList and FileMatcher.GetFiles, and ensure caching of results. Also consider adding an async counterpart.