optimize CompatiblConvertFrom-Yaml to use a script-level variable to …

…store progress

eng/common/scripts/Helpers/Package-Helpers.ps1

@@ -46,7 +46,9 @@ function GetDocsTocDisplayName($pkg) {
   return $displayName
 }
 
-
+if (-not (Test-Path -Path "variable:yqPresent")) {
+  $script:yqPresent = $null  # Initial unset state
+}
 <#
 .SYNOPSIS
 This function is a safe wrapper around `yq` and `ConvertFrom-Yaml` to convert YAML content to a PowerShell HashTable object
@@ -68,27 +70,29 @@ Get-Content -Raw path/to/file.yml | CompatibleConvertFrom-Yaml
 #>
 function CompatibleConvertFrom-Yaml {
   param(
-    [Parameter(Mandatory=$true, ValueFromPipeline=$true)]
+    [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
     [string]$Content
   )
 
   if (!($Content)) {
     throw "Content to parse is a required input."
   }
 
-  # Initialize any variables or checks that need to be done once
-  $yqPresent = Get-Command 'yq' -ErrorAction SilentlyContinue
-  if (-not $yqPresent) {
-    . (Join-Path $PSScriptRoot PSModule-Helpers.ps1)
-    Install-ModuleIfNotInstalled -WhatIf:$false "powershell-yaml" "0.4.1" | Import-Module
+  if ($null -eq $script:yqPresent) {
+    $script:yqPresent = [bool](Get-Command 'yq' -ErrorAction SilentlyContinue)
+
+    if (-not $script:yqPresent) {
+      Write-Host "yqPresent evaluated to null, then false."
+      . (Join-Path $PSScriptRoot PSModule-Helpers.ps1)
+      Install-ModuleIfNotInstalled -WhatIf:$false "powershell-yaml" "0.4.1" | Import-Module
+    }
   }
 
-  # Process the content (for example, you could convert from YAML here)
-  if ($yqPresent) {
-      return ($content | yq -o=json | ConvertFrom-Json -AsHashTable)
+  if ($script:yqPresent) {
+    return ($content | yq -o=json | ConvertFrom-Json -AsHashTable)
   }
   else {
-      return ConvertFrom-Yaml $content
+    return ConvertFrom-Yaml $content
   }
 }