Add powershell completion support

Initial version of powershell tab completion. It completes
commands and container names.

Signed-off-by: Sam Neirinck <sam@samneirinck.com>

contrib/completion/powershell/posh-docker.psm1

@@ -0,0 +1,179 @@
+# Powershell completion for docker
+
+### Prerequisite
+# Docker.exe needs to be in your PATH.
+# If the command is not found, you will need to add a docker alias or add the docker installation folder (e.g. `%ProgramFiles%\Docker Toolbox`) to your PATH environment variable.
+
+### Installation (Latest stable)
+# Windows 10 / Windows Server 2016: 
+# 1. Open a powershell prompt
+# 2. Run `Install-Module -Scope CurrentUser posh-docker`
+#
+# Earlier Windows versions:
+# 1. Install [PackageManagement PowerShell Modules Preview](https://www.microsoft.com/en-us/download/details.aspx?id=49186)
+# 2. Open a powershell prompt
+# 3. Run `Install-Module -Scope CurrentUser posh-docker`
+
+### Installation (From source)
+# Copy this file to the %userprofile%\Documents\WindowsPowerShell\Modules\posh-docker directory (create directories as needed)
+
+### Usage
+# After installation, execute the following line to enable autocompletion for the current powershell session:
+#
+# Import-Module posh-docker
+#
+# To make it persistent, add the above line to your profile. For example, run `notepad $PROFILE` and insert the line above.
+
+$global:DockerCompletion = @{}
+
+$script:flagRegex = "^  (-[^, =]+),? ?(--[^= ]+)?"
+
+function script:Get-Containers($filter)
+{
+    if ($filter -eq $null)
+    {
+       docker ps -a --no-trunc --format "{{.Names}}"
+    } else {
+       docker ps -a --no-trunc --format "{{.Names}}" --filter $filter
+    }
+}
+
+function script:Get-AutoCompleteResult
+{
+    param([Parameter(ValueFromPipeline=$true)] $value)
+    
+    Process
+    {
+        New-Object System.Management.Automation.CompletionResult $value
+    }
+}
+
+filter script:MatchingCommand($commandName)
+{
+    if ($_.StartsWith($commandName))
+    {
+        $_
+    }
+}
+
+$completion_Docker = {
+    param($commandName, $commandAst, $cursorPosition)
+
+    $command = $null
+    $commandParameters = @{}
+    $state = "Unknown"
+    $wordToComplete = $commandAst.CommandElements | Where-Object { $_.ToString() -eq $commandName } | Foreach-Object { $commandAst.CommandElements.IndexOf($_) }
+
+    for ($i=1; $i -lt $commandAst.CommandElements.Count; $i++)
+    {
+        $p = $commandAst.CommandElements[$i].ToString()
+
+        if ($p.StartsWith("-"))
+        {
+            if ($state -eq "Unknown" -or $state -eq "Options")
+            {
+                $commandParameters[$i] = "Option"
+                $state = "Options"
+            }
+            else
+            {
+                $commandParameters[$i] = "CommandOption"
+                $state = "CommandOptions"
+            }
+        } 
+        else 
+        {
+            if ($state -ne "CommandOptions")
+            {
+                $commandParameters[$i] = "Command"
+                $command = $p
+                $state = "CommandOptions"
+            } 
+            else 
+            {
+                $commandParameters[$i] = "CommandOther"
+            }
+        }
+    }
+
+    if ($global:DockerCompletion.Count -eq 0)
+    {
+        $global:DockerCompletion["commands"] = @{}
+        $global:DockerCompletion["options"] = @()
+        
+        docker --help | ForEach-Object {
+            Write-Output $_
+            if ($_ -match "^    (\w+)\s+(.+)")
+            {
+                $global:DockerCompletion["commands"][$Matches[1]] = @{}
+                
+                $currentCommand = $global:DockerCompletion["commands"][$Matches[1]]
+                $currentCommand["options"] = @()
+            }
+            elseif ($_ -match $flagRegex)
+            {
+                $global:DockerCompletion["options"] += $Matches[1]
+                if ($Matches[2] -ne $null)
+                {
+                    $global:DockerCompletion["options"] += $Matches[2]
+                 }
+            }
+        }
+
+    }
+    
+    if ($wordToComplete -eq $null)
+    {
+        $commandToComplete = "Command"
+        if ($commandParameters.Count -gt 0)
+        {
+            if ($commandParameters[$commandParameters.Count] -eq "Command")
+            {
+                $commandToComplete = "CommandOther"
+            }
+        } 
+    } else {
+        $commandToComplete = $commandParameters[$wordToComplete]
+    }
+
+    switch ($commandToComplete)
+    {
+        "Command" { $global:DockerCompletion["commands"].Keys | MatchingCommand -Command $commandName | Sort-Object | Get-AutoCompleteResult }
+        "Option" { $global:DockerCompletion["options"] | MatchingCommand -Command $commandName | Sort-Object | Get-AutoCompleteResult }
+        "CommandOption" { 
+            $options = $global:DockerCompletion["commands"][$command]["options"]
+            if ($options.Count -eq 0)
+            {
+                docker $command --help | % {
+                if ($_ -match $flagRegex)
+                    {
+                        $options += $Matches[1]
+                        if ($Matches[2] -ne $null)
+                        {
+                            $options += $Matches[2]
+                        }
+                    }
+                }
+            }
+
+            $global:DockerCompletion["commands"][$command]["options"] = $options
+            $options | MatchingCommand -Command $commandName | Sort-Object | Get-AutoCompleteResult
+        }
+        "CommandOther" {
+            $filter = $null 
+            switch ($command)
+            {
+                "start" { $filter = "status=exited" }
+                "stop" { $filter = "status=running" }
+            }
+            Get-Containers $filter | MatchingCommand -Command $commandName | Sort-Object | Get-AutoCompleteResult
+        }
+        default { $global:DockerCompletion["commands"].Keys | MatchingCommand -Command $commandName }
+    }
+}
+
+# Register the TabExpension2 function
+if (-not $global:options) { $global:options = @{CustomArgumentCompleters = @{};NativeArgumentCompleters = @{}}}
+$global:options['NativeArgumentCompleters']['docker'] = $Completion_Docker
+
+$function:tabexpansion2 = $function:tabexpansion2 -replace 'End\r\n{','End { if ($null -ne $options) { $options += $global:options} else {$options = $global:options}'