CODEWITHSUNDEEP
linqpowershell
James Ko
James Ko

Reputation: 34559

What is the PowerShell equivalent of LINQ's All()?

I'm trying to test if a condition is true for all items in an array in PowerShell (similarly to LINQ's All function). What would be the 'proper' way to do this in PowerShell, short of writing a manual for-loop?

To be specific, here is the code I'm trying to translate from C#:

public static IEnumerable<string> FilterNamespaces(IEnumerable<string> namespaces)
  => namespaces
     .Where(ns => namespaces
       .Where(n => n != ns)
         .All(n => !Regex.IsMatch(n, $@"{Regex.Escape(ns)}[\.\n]")))
     .Distinct();

Upvotes: 2

Views: 2163

Answers (1)

Frode F.
Frode F.

Reputation: 54911

I wouldn't recreate the C#-code in powershell, but rather do it the PowerShell-way. Ex:

function Filter-Namespaces ([string[]]$Namespaces) {
  $Namespaces | Where-Object {
    $thisNamespace = $_;
    (
      $Namespaces | ForEach-Object { $_ -match "^$([regex]::Escape($thisNamespace))\." }
    ) -notcontains $true
  } | Select-Object -Unique
}

Filter-Namespaces -Namespaces $values

System.Windows.Input
System.Windows.Converters
System.Windows.Markup.Primitives
System.IO.Packaging

However, to answer your question, you could do it the manual way:

$values = "System",
"System.Windows",
"System.Windows.Input",
"System.Windows.Converters",
"System.Windows.Markup",
"System.Windows.Markup.Primitives",
"System.IO",
"System.IO.Packaging"

($values | ForEach-Object { $_ -match 'System' }) -notcontains $false

True

Or you could create a function for it: 

function Test-All {
    [CmdletBinding()]
    param(
    [Parameter(Mandatory=$true)]
    $Condition,
    [Parameter(Mandatory=$true,ValueFromPipeline=$true)]
    $InputObject
    )

    begin { $result = $true }
    process {
        $InputObject | Foreach-Object { 
            if (-not (& $Condition)) { $result = $false }
        }
    }
    end { $result }
}

$values = "System",
"System.Windows",
"System.Windows.Input",
"System.Windows.Converters",
"System.Windows.Markup",
"System.Windows.Markup.Primitives",
"System.IO",
"System.IO.Packaging"

#Using pipeline
$values | Test-All { $_ -match 'System' }

#Using array arguemtn
Test-All -Condition { $_ -match 'System' } -InputObject $values
#Using single value argument
Test-All -Condition { $_ -match 'System' } -InputObject $values[0]

Or you could compile the C# code or load an already compiled dll using Add-Type.

Upvotes: 7

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