Error when trying to activate PredictionMode

[belotn]

Hello,

When i try to activate PredictionMode, i ran into an error saying that the mode cannot be activated.

Environment

PSReadline version: 2.1.0
os: 6.3.9600.16384 (winblue_rtm.130821-1623)
PS file version: 10.0.14409.1005 (rs1_srvoob.161208-1155)
HostName: ConsoleHost
BufferWidth: 170
BufferHeight: 500

Exception report

Set-PSReadLineOption : The predictive suggestion feature cannot be enabled because the console output doesn't support virtual terminal processing or it's redirected.
Au caractère Ligne:1 : 1

• Set-PSReadLineOption -PredictionSource History

•   + CategoryInfo          : NotSpecified: (:) [Set-PSReadLineOption], ArgumentException
    + FullyQualifiedErrorId : System.ArgumentException,Microsoft.PowerShell.SetPSReadLineOption
  
  

Steps to reproduce

Set-PSReadLineOption -PredictionSource History

Expected behavior

Actual behavior

[daxian-dbw]

That's by design. You are uisng Windows 8, which doesn't support Vitual Terminal sequences in console output. The predicitive intellisense feature depends on the VT sequences support.

[SeidChr]

how can i test for this virtual terminal support?

[daxian-dbw]

On Windows, if virtual terminal is supported, PowerShell will turn it on by default. To quickly verify, run "`e[44;1mYEAH YEAH YEAH YEAH`e[0m", and see if the output is formatted like the following:

If not, then virtual terminal is not supported.

[SeidChr]

@daxian-dbw
I have the activation of this in my profile, which is also being used in terminals that do not support this. There muss be a way to run the same test they do, in order to avoid seeing errors in the log for no useful reason
Right now i just see an error when it's activated, without any way of avoiding it

[hongwen000]

My workaround:

function Test-WindowsTerminal {
    $p = (Get-Process -Id $PID)
    while($p -Ne $null -and $p.GetType().Name -Eq "Process") {
        $name = $p.Name
        if($name -Eq "WindowsTerminal") {
            return $True
        }
        $p = $p.parent
    }
    return $False
}

Test-WindowsTerminal

[BusHero]

A more complex version:

function IsVirtualTerminalProcessingEnabled {
	$MethodDefinitions = @'
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr GetStdHandle(int nStdHandle);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern bool GetConsoleMode(IntPtr hConsoleHandle, out uint lpMode);
'@
	$Kernel32 = Add-Type -MemberDefinition $MethodDefinitions -Name 'Kernel32' -Namespace 'Win32' -PassThru
	$hConsoleHandle = $Kernel32::GetStdHandle(-11) # STD_OUTPUT_HANDLE
	$mode = 0
	$Kernel32::GetConsoleMode($hConsoleHandle, [ref]$mode) >$null
	if ($mode -band 0x0004) { # 0x0004 ENABLE_VIRTUAL_TERMINAL_PROCESSING
		return $true
	}
	return $false
}

function CanUsePredictionSource {
	return (! [System.Console]::IsOutputRedirected) -and (IsVirtualTerminalProcessingEnabled)
}

Basically, a powershell version of the check used by PSReadLine here

[daxian-dbw]

Right now i just see an error when it's activated, without any way of avoiding it

Another way is to wrap Set-PSReadLineOption -PredictionSource History in a try/catch block, and ignore the error in case the cmdlet fails to run.

[WojciechNagorski]

The profile file should look:

function IsVirtualTerminalProcessingEnabled {
	$MethodDefinitions = @'
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr GetStdHandle(int nStdHandle);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern bool GetConsoleMode(IntPtr hConsoleHandle, out uint lpMode);
'@
	$Kernel32 = Add-Type -MemberDefinition $MethodDefinitions -Name 'Kernel32' -Namespace 'Win32' -PassThru
	$hConsoleHandle = $Kernel32::GetStdHandle(-11) # STD_OUTPUT_HANDLE
	$mode = 0
	$Kernel32::GetConsoleMode($hConsoleHandle, [ref]$mode) >$null
	if ($mode -band 0x0004) { # 0x0004 ENABLE_VIRTUAL_TERMINAL_PROCESSING
		return $true
	}
	return $false
}

function CanUsePredictionSource {
	return (! [System.Console]::IsOutputRedirected) -and (IsVirtualTerminalProcessingEnabled)
}

if (CanUsePredictionSource){ 
  Import-Module -Name Terminal-Icons
  Import-Module PSReadLine
  Set-PSReadLineOption -PredictionViewStyle ListView -PredictionSource History -HistoryNoDuplicates
}