PowerShell equivalent of LINQ Any()?

Question

I would like to find all directories at the top level from the location of the script that are stored in subversion.

In C# it would be something like this

Answer 1

I recommend the following solution:

<#
.SYNOPSIS 
   Tests if any object in an array matches the expression

.EXAMPLE
    @( "red", "blue" ) | Where-Any { $_ -eq "blue" } | Write-Host
#>
function Where-Any 
{
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $True)]
        $Condition,

        [Parameter(Mandatory = $True, ValueFromPipeline = $True)]
        $Item
    )

    begin {
        [bool]$isMatch = $False
    }

    process {
      if (& $Condition $Item) {
          [bool]$isMatch = $true
      }
    }

    end {
        Write-Output $isMatch
    }
}

# optional alias
New-Alias any Where-Any

Answer 2

It's actually quite simple - just select first $true (formatted for clarity):

[bool] ($source `
        | foreach { [bool] (<predicate>) } `
        | where { $_ } `
        | select -first 1)

Alternative way:

($source `
        | where { <predicate> } `
        | foreach { $true } `
        | select -first 1)

Answer 3

I think that the best answer here is the function proposed by @JaredPar, but if you like one-liners as I do I'd like to propose following Any one-liner:

# Any item is greater than 5
$result = $arr | %{ $match = $false }{ $match = $match -or $_ -gt 5 }{ $match }

%{ $match = $false }{ $match = $match -or YOUR_CONDITION }{ $match } checks that at least one item match condition.

One note - usually the Any operation evaluates the array until it finds the first item matching the condition. But this code evaluates all items.

Just to mention, you can easily adjust it to become All one-liner:

# All items are greater than zero
$result = $arr | %{ $match = $false }{ $match = $match -and $_ -gt 0 }{ $match }

%{ $match = $false }{ $match = $match -and YOUR_CONDITION }{ $match } checks that all items match condition.

Notice, that to check Any you need -or and to check All you need -and.

Answer 4

I ended up doing it with a count:

$directoryContainsSvn = {
    (Get-ChildItem $_.Name -force | ? {$_.PsIsContainer -and $_.Name -eq "_svn" -or $_.Name -eq ".svn"} | Measure-Object).Count -eq 1
}
$svnDirs = Get-ChildItem | ? {$_.PsIsContainer} | ? $directoryContainsSvn

Answer 5

You can tighten this up a bit:

gci -fo | ?{$_.PSIsContainer -and `
            (gci $_ -r -fo | ?{$_.PSIsContainer -and $_ -match '[_.]svn$'})}

Note - passing $__.Name to the nested gci is unnecessary. Passing it $_ is sufficent.