Example of a prebuild file for an Unreal plugin that replaces preprocessor code marked up with version information.

Prebuild.ps1

$EngineVersionData = ((Get-Content $Env:EngineDir/Build/Build.version) | ConvertFrom-JSON)
$EngineVersion = "$($EngineVersionData.MajorVersion).$($EngineVersionData.MinorVersion)"
function IsDecimal($value){
    Try{
        [System.Decimal]$value | Out-Null
        $true
    } Catch {
        $false
    }
}
function ReplaceVersionMacrosForVersion($file, $version_decimal, $version_macro)
{
    $disabled_text = "#if 0 // " + $version_macro
    $enabled_text = "#if 1 // " + $version_macro
    $content = (Get-Content $file)
    if ([System.Decimal]$EngineVersion -ge [System.Decimal]$version_decimal)
    {
        if ($content -like "*$disabled_text*")
        {
            Write-Output "Enabling $version_macro block in $file"
            $content -replace $disabled_text, $enabled_text | Out-File $file
        }
    }
    else
    {
        if ($content -like "*$enabled_text*")
        {
            Write-Output "Disabling $version_macro block in $file"
            $content -replace $enabled_text, $disabled_text | Out-File $file
        }
    }
}
function ReplaceVersionMacros($file)
{
    ReplaceVersionMacrosForVersion $file "4.17" "UE_4_17_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.18" "UE_4_18_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.19" "UE_4_19_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.20" "UE_4_20_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.21" "UE_4_21_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.22" "UE_4_22_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.23" "UE_4_23_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.24" "UE_4_24_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.25" "UE_4_25_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.26" "UE_4_26_OR_LATER"
    ReplaceVersionMacrosForVersion $file "4.27" "UE_4_27_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.0" "UE_5_0_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.1" "UE_5_1_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.2" "UE_5_2_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.3" "UE_5_3_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.4" "UE_5_4_OR_LATER"
    ReplaceVersionMacrosForVersion $file "5.5" "UE_5_5_OR_LATER"
}
if (IsDecimal($EngineVersion))
{
    Get-ChildItem -Path "$Env:PluginDir\Source\" -Recurse -Include *.h,*.cpp,*.c,*.inl,*.hpp |
        Foreach-Object {
            ReplaceVersionMacros($_.FullName)
        }
}
else
{
    Write-Output "Failed to recognize Engine Version: $EngineVersion"
}