public static IEnumerable <FileSystemInfo> Traverse(this DirectoryInfo root, string pattern, bool caseSensitive, bool emitFiles, bool emitDirectories)
{
var parser = new Parser(pattern);
var segments = parser.ParseTree().Segments;
var cache = new TraverseOptions(caseSensitive, emitFiles, emitDirectories);
return(segments.Length == 0 ? new FileSystemInfo[0] : Traverse(root, segments, cache));
}
internal static IEnumerable <FileSystemInfo> Traverse(DirectoryInfo root, Segment[] segments, int segmentIndex,
TraverseOptions options)
{
if (segmentIndex == segments.Length)
{
return(options.EmitDirectories
? Enumerable.Repeat <FileSystemInfo>(root, 1)
: emptyFileSystemInfoArray);
}
var segment = segments[segmentIndex];
switch (segment)
{
case DirectorySegment directorySegment:
{
var filesToEmit =
(options.EmitFiles && segmentIndex == segments.Length - 1)
? options.GetFiles(root).Where(file => directorySegment.MatchesSegment(file.Name, options.CaseSensitive)).Cast <FileSystemInfo>()
: emptyFileSystemInfoArray;
var dirSegmentItems = from directory in options.GetDirectories(root)
where directorySegment.MatchesSegment(directory.Name, options.CaseSensitive)
from item in Traverse(directory, segments, segmentIndex + 1, options)
select item;
return(filesToEmit.Concat(dirSegmentItems));
}
case DirectoryWildcard _:
{
var filesToEmit =
(options.EmitFiles && segmentIndex == segments.Length - 1)
? options.GetFiles(root).Cast <FileSystemInfo>()
: emptyFileSystemInfoArray;
// match zero path segments, consuming DirectoryWildcard
var zeroMatch = Traverse(root, segments, segmentIndex + 1, options);
// match consume 1 path segment but not the Wildcard
var files = from directory in options.GetDirectories(root)
from item in Traverse(directory, segments, segmentIndex, options)
select item;
return(filesToEmit.Concat(zeroMatch).Concat(files));
}
default:
return(emptyFileSystemInfoArray);
}
}
private static IEnumerable <FileSystemInfo> Traverse(List <DirectoryInfo> roots, Segment[] segments, TraverseOptions options) => new PathTraverserEnumerable(roots, segments, options);
internal static IEnumerable <FileSystemInfo> Traverse(DirectoryInfo root, Segment[] segments, TraverseOptions options) =>
Traverse(new List <DirectoryInfo> {
root
}, segments, options);
public PathTraverserEnumerable(List <DirectoryInfo> roots, Segment[] segments, TraverseOptions options)
{
this._originalRoots = roots;
this._segments = segments;
this._options = options;
}