Pass PowerShell aliases down to posh-git TabExpansion autocomplete function

[humidair1999]

I have PS aliases for git, defined as such:

function git-branch-delete { git branch -D $args }
Set-Alias gbd git-branch-delete

function git-checkout { git checkout $args }
Set-Alias gco git-checkout

The $args represents a branch name, which posh-git would typically autocomplete. However, since aliases are not passed down to posh-git, autocompletion doesn't work.

I monkey-patched this functionality myself, using the technique described in this SO answer:

function TabExpansion($line, $lastWord) {
    # aliases that have some form of tab autocomplete functionality
    # NOTE: ADDED POST-INSTALL BY USER
    $line = $line -replace '^gco ', 'git checkout '
    $line = $line -replace '^gbd ', 'git branch '
    # end aliases

    # rest of the function...
}

It'd be super rad if posh-git could somehow retrieve existing PS aliases related to git functionality like this and patch it into posh-git's autocompletion functionality.

I prefer to use PS aliases over git aliases, primarily for brevity - I'm able to do gcm instead of git co or similar.

[dahlbyk]

Working through open issues and realized that I never commented. This is a great idea and I would totally accept a PR for a generalized version of this.

[MisinformedDNA]

I can easily see aliases working, but functions are tricky.

For aliases, we just need to insert (Get-Alias $alias).Definition somewhere.

Assuming we have

function git-checkout { git checkout $args }
set-alias gco git-checkout

I have no idea how I would interpret that. Would I grab the ScriptBlock to do a find/replace? But what if it's multiple lines? What if I executed something in the ScriptBlock? Well we can't run the function as is because we aren't ready to execute. We still want tab completion. But what if the function returned a string? Assume

> function git-checkout { "git checkout" }
> set-alias gco git-checkout

Then we could run the following:

$command = (Get-Alias $alias).Definition
if (Test-Path Function:/$command) {    # Check if the command is actually a function
    $command = & $alias    # execute
}

Since we are now only dealing with strings we could just create a "dictionary file", kind of like from Export-Alias.

Thoughts?

[dahlbyk]

posh-git wouldn't be responsible for executing the function, we just need to tease out the definition.

You can get the function definition like this. I would try a regex to match the definition on git <args> $args, then swap the match in before expansion.

[MisinformedDNA]

What would you do if there were multiple lines in the definition?

[dahlbyk]

What would you do if there were multiple lines in the definition?

Similar to how we parse $lastBlock, I think you'd want to match between [;|]. I haven't tested it, but something like "(^|[|;])\s*(?<cmd>$(Get-AliasPattern git).* \`$args)\s*($|[|;])", then Expand-GitCommand $matches['cmd'].

This would be a great opportunity to TDD handling different function definitions. 😀

[Clijsters]

I would grab this, since I realized something similiar some months ago.

[jrusbatch]

I'd also love to see this! I alias git to g out of laziness, and I only just now realized that that was the reason I can't tab-complete branch names anymore.

[dahlbyk]

@jrusbatch: I'd also love to see this! I alias git to g out of laziness, and I only just now realized that that was the reason I can't tab-complete branch names anymore.

If g is a normal PowerShell alias (i.e. Set-Alias g git) it should Just Work™️. Are you finding that not to be the case?

[jrusbatch]

@dahlbyk Correct. Although, I was declaring my alias with New-Alias -Name g -Value git -Option Private in my Profile.ps1. After removing -Option Private the tab completion functionality works. I don't remember why I specified that option so I think I'm good for now. Thanks!

[szelpe]

@dahlbyk I have the exact same setup, i.e. having Set-Alias g git in my $profile and tab completion with g worked in beta2 and beta3 but now broken in beta4. Simply does nothing if I type g fet<TAB>.

[szelpe]

Also, if I set the UseLegacyTabExpansion to $True it starts to work again.

[rkeithhill]

@szelpe Your bug is a little different since you alias directly to the git executable as opposed to aliasing to a custom function. Can you submit a new issue?

It turns out PowerShell's built-in Register-ArgumentCompleter does not take into account aliases to native apps that have registered completers. I think the fix for this is pretty easy.

[szelpe]

@szelpe Your bug is a little different since you alias directly to the git executable as opposed to aliasing to a custom function. Can you submit a new issue?

It turns out PowerShell's built-in Register-ArgumentCompleter does not take into account aliases to native apps that have registered completers. I think the fix for this is pretty easy.

Sure: #769

[rkeithhill]

Implemented via PR #779. Thanks @csc027!

[suhaibbaba]

How can do that?
I need to create alias like
gcob master
gcob = git checkout -b
when write gcob m and click tab, I need to show master

[MisinformedDNA]

$scriptBlock = {
     param($commandName, $parameterName, $wordToComplete, $commandAst, $fakeBoundParameters)

     Expand-GitCommand 'git checkout -b '
 }

Register-ArgumentCompleter -CommandName gcob -ScriptBlock $scriptBlock

[suhaibbaba]

@MisinformedDNA
Thanks but It doesn't autocomplete from last word
I mean
gcob mas
It should complete it to gcob master

[MisinformedDNA]

Try this:

$scriptBlock = {
     param($commandName, $parameterName, $wordToComplete, $commandAst, $fakeBoundParameters)

     Expand-GitCommand "git checkout -b $commandName"
 }
 Register-ArgumentCompleter -CommandName gcob -ScriptBlock $scriptBlock

[suhaibbaba]

@MisinformedDNA Thank you and it's working fine
but can you please explain it? and if I need to create multiple custom commands, do I need to create multiple script-blocks?
I mean, I need to create

1. gco => git checkout
2. gcob => git checkout -b
3. gp => git push

like this

Now my profile

function gcob {
    param ($commandComplete)
    git checkout -b ${commandComplete}
}

$scriptBlock = {
     param($commandName, $parameterName, $wordToComplete, $commandAst, $fakeBoundParameters)
     Expand-GitCommand "git checkout -b $commandName"
}

Register-ArgumentCompleter -CommandName gcob -ScriptBlock $scriptBlock

[MisinformedDNA]

Yes, you need separate script blocks for each one.

[suhaibbaba]

@MisinformedDNA gotcha!
Thanks for helping

[MisinformedDNA]

I find that passing in a parameter doesn't work correctly in certain scenarios. For instance, if you run this:

function gl { 
    param ($commandComplete)
    git log $commandComplete
}
$scriptBlock = {
    param($wordToComplete, $commandAst, $cursorPosition)

    Expand-GitCommand "git log $wordToComplete"
}
Register-ArgumentCompleter -Native -CommandName gl -ScriptBlock $scriptBlock

gl-<TAB>

You will get

gl -commandComplete

Instead, I use:

function gl { git log @args }
$scriptBlock = {
    param($wordToComplete, $commandAst, $cursorPosition)

    Expand-GitCommand "git log $wordToComplete"
}
Register-ArgumentCompleter -Native -CommandName gl -ScriptBlock $scriptBlock

NOTE: I've also explicitly set the native parameter (even though it is implied) and changed the names of the script parameters to reflect the native parameters.

[mrbeardad]

The code below works well for me. It will complete the parameter of git subcommand or subsubcommand correctly.

function RegisterGit {
  Invoke-Expression -Command "function global:$($args[0]) { git $($args[1]) @args }"
  $tab = [Scriptblock]::Create("
    param(`$wordToComplete, `$commandAst, `$cursorPosition)
    `$cmdline = `$commandAst.ToString().Replace(`"$($args[0])`", `"`")
    if (`$wordToComplete.Length -ne 0) { `$tail = '' } else { `$tail = ' ' }
    Expand-GitCommand `"git $($args[1]) `$cmdline`$tail`"
  ")
  Register-ArgumentCompleter -CommandName $args[0] -ScriptBlock $tab
}

# define function gst to execute git remote, and register the tab completer for it.
RegisterGit gr "remote"