src/application.ps1
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class ApplicationState { [String] $Id = (New-Guid) [Bool] $Continue = $True [String] $Name = 'Application Name' $Data } function ConvertTo-PowershellSyntax { [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', 'DataVariableName')] [OutputType([String])] Param( [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)] [String] $Value, [String] $DataVariableName = 'Data' ) Write-Output $Value | ForEach-Object { $_ -replace '(?<!(}}[\w\s]*))(?<!{{#[\w\s\-_]*)\s*}}', ')' } | ForEach-Object { $_ -replace '{{(?!#)\s*', "`$(`$$DataVariableName." } } function Get-State { <# .SYNOPSIS Load state from file .EXAMPLE $State = Get-State -Id 'abc-def-ghi' .EXAMPLE $State = 'abc-def-ghi' | Get-State #> [CmdletBinding()] Param( [Parameter(Position = 0, ValueFromPipeline = $True)] [String] $Id, [AllowEmptyString()] [String] $Path ) if ($Path.Length -gt 0 -and (Test-Path $Path)) { "==> Resolved $Path" | Write-Verbose } else { $TempRoot = if ($IsLinux) { '/tmp' } else { $Env:temp } $Path = Join-Path $TempRoot "state-$Id.xml" } "==> Loading state from $Path" | Write-Verbose Import-Clixml -Path $Path } function Invoke-RunApplication { <# .SYNOPSIS Entry point for Powershell CLI application .PARAMETER Init Function to initialize application, executed when application is started. .PARAMETER Loop Code to execute during every application loop, executed when ShouldContinue returns True. .PARAMETER BeforeNext Code to execute at the end of each application loop. It should be used to update the return of ShouldContinue. .PARAMETER SingleRun As its name implies - use this flag to execute one loop of the application .PARAMETER NoCleanup Use this switch to disable removing the application event listeners when the application exits. Application event listeners can be removed manually with: 'application:' | Invoke-StopListen .EXAMPLE # Make a simple app # Initialize your app - $Init is only run once $Init = { 'Getting things ready...' | Write-Color -Green } # Define what your app should do every iteration - $Loop is executed until ShouldContinue returns False $Loop = { Clear-Host 'Doing something super important...' | Write-Color -Gray Start-Sleep 5 } # Start your app Invoke-RunApplication $Init $Loop .EXAMPLE # Make a simple app with state # Note: State is passed to Init, Loop, ShouldContinue, and BeforeNext New-ApplicationTemplate -Save .EXAMPLE # Applications trigger events throughout their lifecycle which can be listened to (most commonly within the Init scriptblock). { say 'Hello' } | on 'application:init' { say 'Wax on' } | on 'application:loop:before' { say 'Wax off' } | on 'application:loop:after' { say 'Goodbye' } | on 'application:exit' # The triggered event will include State as MessageData { $Id = $Event.MessageData.State.Id "`nApplication ID: $Id" | Write-Color -Green } | Invoke-ListenTo 'application:init' #> [CmdletBinding()] Param( [Parameter(Mandatory = $True, Position = 0)] [ScriptBlock] $Init, [Parameter(Mandatory = $True, Position = 1)] [ScriptBlock] $Loop, [Parameter(Position = 2)] [ApplicationState] $State = @{}, [String] $Id, [ScriptBlock] $ShouldContinue, [ScriptBlock] $BeforeNext, [Switch] $ClearState, [Switch] $SingleRun, [Switch] $NoCleanup ) if ($Id.Length -gt 0) { $TempRoot = if ($IsLinux) { '/tmp' } else { $Env:temp } $Path = Join-Path $TempRoot "state-$Id.xml" if ($ClearState -and (Test-Path $Path)) { Remove-Item $Path } if (Test-Path $Path) { "==> Resolved state with ID: $Id" | Write-Verbose try { [ApplicationState]$State = Get-State $Id $State.Id = $Id } catch { "==> Failed to get state with ID: $Id" | Write-Verbose $State = [ApplicationState]@{ Id = $Id } } } else { $State.Id = $Id } } if (-not $State) { $State = [ApplicationState]@{} } if (-not $ShouldContinue) { $ShouldContinue = { $State.Continue -eq $True } } if (-not $BeforeNext) { $BeforeNext = { "`n`nContinue?" | Write-Label -NewLine $State.Continue = ('yes', 'no' | Invoke-Menu) -eq 'yes' } } "Application ID: $($State.Id)" | Write-Verbose 'application:init' | Invoke-FireEvent & $Init $State if ($SingleRun) { 'application:loop:before' | Invoke-FireEvent -Data @{ State = $State } & $Loop $State 'application:loop:after' | Invoke-FireEvent -Data @{ State = $State } } else { while (& $ShouldContinue $State) { 'application:loop:before' | Invoke-FireEvent -Data @{ State = $State } & $Loop $State 'application:loop:after' | Invoke-FireEvent -Data @{ State = $State } & $BeforeNext $State } } 'application:exit' | Invoke-FireEvent -Data @{ State = $State } if (-not $NoCleanup) { 'application:' | Invoke-StopListen } $State.Id } function New-ApplicationTemplate { <# .SYNOPSIS Return boilerplate string of a "scrapp" ("script" + "app") .EXAMPLE New-ApplicationTemplate | Out-File 'my-app.ps1' #> [CmdletBinding()] Param() $Snippet = if (-not $IsLinux) { "{ Invoke-Speak 'Goodbye' `$Id = `$Event.MessageData.State.Id `"``nApplication ID: `$Id``n`" | Write-Color -Magenta } | Invoke-ListenTo 'application:exit' | Out-Null" } else { '' } " #Requires -Modules Prelude [CmdletBinding()] Param( [String] `$Id = 'app', [Switch] `$Clear ) $Empty `$InitialState = @{ Data = 0 } $Empty `$Init = { Clear-Host `$State = `$Args[0] `$Id = `$State.Id 'Application Information:' | Write-Color `"ID = {{#green `$Id}}`" | Write-Label -Color Gray -Indent 2 -NewLine 'Name = {{#green My-App}}' | Write-Label -Color Gray -Indent 2 -NewLine $Snippet '' | Write-Color Start-Sleep 2 } $Empty `$Loop = { Clear-Host `$State = `$Args[0] `$Count = `$State.Data `"Current count is {{#green `$Count}}`" | Write-Color -Cyan `$State.Data++ Save-State `$State.Id `$State | Out-Null Start-Sleep 1 } $Empty Invoke-RunApplication `$Init `$Loop `$InitialState -Id `$Id -ClearState:`$Clear " | Remove-Indent } function New-Template { <# .SYNOPSIS Create render function that interpolates passed object values .PARAMETER Data Pass template data to New-Template when using New-Template within pipe chain (see examples) .EXAMPLE $Function:render = New-Template '<div>Hello {{ name }}!</div>' render @{ name = 'World' } # '<div>Hello World!</div>' Use mustache template syntax! Just like Handlebars.js! .EXAMPLE $Function:render = 'hello {{ name }}' | New-Template @{ name = 'world' } | render # 'hello world' New-Template supports idiomatic powershell pipeline syntax .EXAMPLE $title = New-Template -Template '<h1>{{ text }}</h1>' -DefaultValues @{ text = 'Default' } & $title # '<h1>Default</h1>' & $title @{ text = 'Hello World' } # '<h1>Hello World</h1>' Provide default values for your templates! .EXAMPLE $Function:Div = '<div>{{ v }}</div>' | New-Template $Function:Span = '<span>{{ v }}</span>' | New-Template Div @{ v = Span @{ v = 'Hello World' } } | Write-Output # "<div><span>Hello World</span></div>" Templates can even be nested! .EXAMPLE '{{#green Hello}} {{ name }}' | tpl -Data @{ name = 'World' } | Write-Color Use -Data parameter cause template to return formatted string instead of template function .EXAMPLE 'The answer is {{= $Value + 2 }}' | tpl -Data @{ Value = 40 } # "The answer is 42" Execute PowerShell code within your templates using the {{= ... }} syntax .EXAMPLE 'The fox says {{= $Env:SomeRandomValue }}!!!' | New-Template -NoData Even access environment variables. Use -NoData when no data needs to be passed. .EXAMPLE '{{- This is a comment }}Super important stuff' | tpl -NoData Add comments to templates using {{- ... }} syntax #> [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSAvoidUsingInvokeExpression', '')] [CmdletBinding()] [Alias('tpl')] [OutputType([String])] Param( [Parameter(ParameterSetName = 'string', Mandatory = $True, Position = 0, ValueFromPipeline = $True)] [String] $Template, [Parameter(ParameterSetName = 'file')] [String] $File, [Alias('Data')] [Hashtable] $Binding = @{}, [Switch] $NoData, [Hashtable] $DefaultValues = @{}, [Switch] $PassThru ) Begin { $Pattern = '(?<expression>{{(?<indicator>(=|-|#))?\s+(?<variable>.*?)\s*}})' $Renderer = { Param( [ScriptBlock] $Script, [Hashtable] $Binding = @{} ) $Binding.GetEnumerator() | ForEach-Object { New-Variable -Name $_.Key -Value $_.Value } try { $Script.Invoke() } catch { throw $_ } } $Evaluator = { Param($Match) $Groups = $Match.Groups $Value = $Groups[1].Value $Indicator = $Groups | Where-Object { $_.Name -eq 'indicator' } | Get-Property 'Value' $Variable = $Groups | Where-Object { $_.Name -eq 'variable' } | Get-Property 'Value' switch ($Indicator) { '#' { $Value } '-' { '' } '=' { $Block = [ScriptBlock]::Create('$($(' + $Variable + ') | Write-Output)') $Binding = $DefaultValues, $Binding | Invoke-ObjectMerge try { $Powershell = [Powershell]::Create() $Powershell.AddScript($Renderer).AddParameter('Binding', $Binding).AddParameter('Script', $Block).Invoke() } finally { if ($Powershell) { $Powershell.Dispose() } } } Default { "`${${Variable}}" } } } } Process { if ($File) { $Path = Resolve-Path $File $Template = Get-Content $Path -Raw } $TemplateScriptBlock = [ScriptBlock]::Create('$("' + [Regex]::Replace($Template, $Pattern, $Evaluator) + '" | Write-Output)') if (($Binding.Count -gt 0) -or $NoData) { if ($PassThru) { return $Template exit } $Binding = $DefaultValues, $Binding | Invoke-ObjectMerge try { $Powershell = [Powershell]::Create() $Powershell.AddScript($Renderer).AddParameter('Binding', $Binding).AddParameter('Script', $TemplateScriptBlock).Invoke() } finally { if ($Powershell) { $Powershell.Dispose() } } } else { { Param( [Parameter(Position = 0, ValueFromPipeline = $True)] [Alias('Data')] [Hashtable] $Binding = @{}, [Switch] $PassThru ) if ($PassThru) { return $Template exit } $Binding = $DefaultValues, $Binding | Invoke-ObjectMerge try { $Powershell = [Powershell]::Create() $Powershell.AddScript($Renderer).AddParameter('Binding', $Binding).AddParameter('Script', $TemplateScriptBlock).Invoke() } finally { if ($Powershell) { $Powershell.Dispose() } } }.GetNewClosure() } } } function Remove-Indent { <# .SYNOPSIS Remove indentation of multi-line (or single line) strings ==> Good for removing spaces added to template strings because of alignment with code. #> [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', 'Size')] [CmdletBinding()] Param( [Parameter(Mandatory = $True, ValueFromPipeline = $True)] [AllowEmptyString()] [String] $From, [Int] $Size = 4 ) Process { $Lines = $From -split '\n' $Delimiter = if ($Lines.Count -eq 1) { '' } else { "`n" } $Callback = { $Args[0], $Args[1] -join $Delimiter } $Lines | Where-Object { $_.Length -ge $Size } | ForEach-Object { $_.SubString($Size) } | Invoke-Reduce -Callback $Callback -InitialValue '' } } function Save-State { <# .SYNOPSIS Save state object as CliXml in temp directory .EXAMPLE Set-State -Id 'my-app -State @{ Data = 42 } .EXAMPLE Set-State 'my-app' @{ Data = 42 } .EXAMPLE @{ Data = 42 } | Set-State 'my-app' #> [CmdletBinding(SupportsShouldProcess = $True)] Param( [Parameter(Mandatory = $True, Position = 0)] [String] $Id, [Parameter(Mandatory = $True, Position = 1, ValueFromPipeline = $True)] [PSObject] $State, [String] $Path ) if (-not $Path) { $TempRoot = if ($IsLinux) { '/tmp' } else { $Env:temp } $Path = Join-Path $TempRoot "state-$Id.xml" } if ($PSCmdlet.ShouldProcess($Path)) { $State.Id = $Id $State | Export-Clixml -Path $Path "==> Saved state to $Path" | Write-Verbose } else { "==> Would have saved state to $Path" | Write-Verbose } $Path } |