Dir.glob doesn't support recursive matching using double star ("**") wildcard

[5t111111]

Although I don't know whether this is intended or not, Dir.glob doesn't support recursive matching using double star ("**") wildcard.

when the below directory tree and the program are given:

.
├── dir_b
│   ├── dir_c
│   │   ├── file_c_1
│   │   └── file_c_2
│   ├── file_b_1
│   └── file_b_2
├── file_a_1
├── file_a_2
└── glob_check.cr

Dir.glob("**/*") do |file|
  puts file
end

while when I run this code as Ruby I get:

$ ruby glob_check.cr 
dir_b
dir_b/dir_c
dir_b/dir_c/file_c_1
dir_b/dir_c/file_c_2
dir_b/file_b_1
dir_b/file_b_2
file_a_1
file_a_2
glob_check.cr

as Crystal I get:

$ crystal glob_check.cr 
dir_b/dir_c
dir_b/file_b_1
dir_b/file_b_2

Crystal 0.7.7 on OS X.

[jhass]

Yes, unfortunately the backing libc call glob(3) doesn't support it and everybody seems to reimplement it all the time.

[5t111111]

thanks, i see the point.

[jhass]

To clarify, we totally want this, it's just that nobody had time or motivation yet to do a full Crystal glob implementation.

[asterite]

Yes! We know this now for a long time but it's not a simple thing to do. As @jhass says, we would really love having this functionality, though. If somebody want's to tackle this, please let us know! It should be a fun little project, plus it's very easy to test.

[pgkos]

I suppose that any glob pattern can be translated into a regex? If yes, then the implementation should be quite easy. We will just match the paths using the regex. Later, we might implement a hand-written glob matcher for efficiency.

If there is a ** in the pattern, we will recurse infinitely into the subdirectories. If there is no **, we can optimize the traversal by counting the depth of the pattern and not recursing too deeply.

[ysbaddaden]

Or maybe keep using LibC.glob to match individual files/folders but manually traverse directories on **.