Modify MatcherContext so that it returns an IEnumerable

[aspnet-hello]

From @reliak on Monday, November 23, 2015 6:18:25 AM

In https://github.com/aspnet/FileSystem/blob/dev/src/Microsoft.Extensions.FileSystemGlobbing/Internal/MatcherContext.cs#L44 the Execute method returns a PatternMatchingResult object.

To better support parallel operations, it would be great to return an IEnumerable<FilePatternMatch> with an yield inside the Execute method. This way I can start working when the first file was found and I do not need to wait till the end of the Execute method.

Copied from original issue: aspnet/FileSystem#143

[aspnet-hello]

From @muratg on Tuesday, December 8, 2015 10:27:13 AM

PatternMatchingResult has Files property which is an IEnumerable<FilePatternMatch>.

Though if you look at https://github.com/aspnet/FileSystem/blob/dev/src/Microsoft.Extensions.FileSystemGlobbing/Internal/MatcherContext.cs#L35, this is already not lazy.

Do you have any measurements to suggest a design change?

[aspnet-hello]

From @reliak on Tuesday, December 8, 2015 10:35:47 AM

I haven't done any performance measurements, so I can't tell you whether it's worth to change the design.
But yielding a result when it's found should perform better in terms of parallelization, instead of collecting all results and then returning all at once.

[aspnet-hello]

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