Extended dir Pattern

Here's a snippet I came up with on a larger project that you might find useful:

Function Rec($path){
 if($path[-1] -eq '/' -or $path[-1] -eq '\'){
 $path += '**'
 }
 $rec = $path -split '**', 0, 'simplematch'
 if($rec.length -gt 1){ #recursive
 dir -r $rec[0] | ?{ !($_.PSIsContainer) -and ($_.FullName -like ($rec -join '*')) } | %{ $_.FullName }
 } else { #non-recursive
 dir $rec[0] | ?{ !$_.PSIsContainer } | %{ $_.FullName }
 }
}

Rec("C:\test\**\sub2\*.sml")
#C:\test\sub0\sub3\sub2\set.sml
#C:\test\sub0\sub3\sub2\vector3.sml
#C:\test\sub1\sub2\set.sml
#C:\test\sub1\sub2\vector3.sml

Hi TNO, Does this return the same results with your file structure?
 

Get-ChildItem "c:\test" -Recurse | where {$_.basename -eq "sub2"} | foreach {Resolve-Path "$($_.fullname)\*.sml"} 
'Or with Alias'
LS c:\test -R|?{$_.basename-eq"sub2"}|%{rvpa "$($_.fullname)\*.sml"}

"Resolve-Path"   Something I wish I knew about earlier.
 
What would something like this look like?
 
C:\**\sub1\**\sub7\*.sml
 
 

Now that's getting really tricky.
I am assuming ** represents one or more folders.
 
So a valid path could be
C:\sub0\sub1\sub2\sub3\sub7\xx.sml
or either
C:\sub0\sub2\sub1\sub3\sub7\yy.sml

Correct. I'm hopeful that you can pull something short and elegant out of thin air

My original idea was to use a REGEX to check the path but gave up on that idea after coming up with a script that fit the first scenario. REGEX still seems to be the best course of action but its not one of my strengths.  It seems your recursive script is the most elegant for these multiple path patterns.   I will have another play tonight.

Yeah, this got complex way too fast. I think falling back to "-like" is much smarter:

 function recDir([string]$p){ 
 if($p[-1] -eq '/' -or $p[-1] -eq '\'){ $p += '**' } 
 
 if($p.indexOf('**') -gt -1){ 
 dir -r $p.substring(0,$p.indexOf('**')) |  
 ?{ !$_.PSIsContainer -and $_.FullName -like $p} | %{$_.FullName} 
 } else { 
 dir $p | ?{ !$_.PSIsContainer } | %{ $_.FullName } 
 } 
 } 

I have started to study regex and used this as a practical problem. Here is a regex solution, it is not in a function but if you follow through my workings you probably could rebuild the regex for different directory patterns if required.
 
 
# valid file structure
$a="C:\sub0\sub1\sub2\sub3\sub7\xA12_ -x.sml"
$b="C:\sub0\sub2\sub1\sub3\sub7\yy.sml"
# simple file matches
$a -match ".*?\.sml"
$a -match "C:\\.*?\.sml"
# powershell regex is case insensitive by default so a-z matches uppercase too
$a -match "[a-z]:\\.*?\.sml"

# match specific directory structure
$a -match "[a-z]:\\.*?\\sub1\\.*?sub7\\.*?\.sml"
# use variables
$dir1="sub1"
$dir2="sub7"
$a -match "[a-z]:\\.*?\\($dir1)\\.*?($dir2)\\.*?\.sml"
# use variable for extension too
$ext="\.sml"
$a -match "[a-z]:\\.*?\\($dir1)\\.*?($dir2)\\.*?($ext)"
# tighten up the directory matching
$a -match "[a-z]:\\.*?($dir1).*?($dir2)\\.*?($ext)"
# tighten up the filename matching
$a -match "^[a-z]:\\.*?($dir1).*?($dir2)\\[a-z0-9-_\s]{0,256}($ext)$"
 
# final script
dir c:\ -r -ea 0| %{if($_.fullname -match "^[a-z]:\\.*?($dir1).*?($dir2)\\[a-z0-9-_\s]{0,256}($ext)$"){$_.fullname}}