Source/Public/ConvertTo-Expression.ps1
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.SYNOPSIS Serializes an object to a PowerShell expression. .DESCRIPTION The ConvertTo-Expression cmdlet converts (serializes) an object to a PowerShell expression. The object can be stored in a variable, (.psd1) file or any other common storage for later use or to be ported to another system. expressions might be restored to an object using the native Invoke-Expression cmdlet: $Object = Invoke-Expression ($Object | ConvertTo-Expression) Or using the [PSNode Object Parser][1] (*under construction*). > [!Note] > Some object types can not be constructed from a a simple serialized expression .INPUTS Any. Each objects provided through the pipeline will converted to an expression. To concatenate all piped objects in a single expression, use the unary comma operator, e.g.: `,$Object | ConvertTo-Expression` .OUTPUTS String[]. `ConvertTo-Expression` returns a PowerShell [String] expression for each input object. .PARAMETER InputObject Specifies the objects to convert to a PowerShell expression. Enter a variable that contains the objects, or type a command or expression that gets the objects. You can also pipe one or more objects to `ConvertTo-Expression.` .PARAMETER LanguageMode Defines which object types are allowed for the serialization, see: [About language modes][2] If a specific type isn't allowed in the given language mode, it will be substituted by: * **`$Null`** in case of a null value * **`$False`** in case of a boolean false * **`$True`** in case of a boolean true * **A number** in case of a primitive value * **A string** in case of a string or any other **leaf** node * `@(...)` for an array (**list** node) * `@{...}` for any dictionary, PSCustomObject or Component (aka **map** node) See the [PSNode Object Parser][1] for a detailed definition on node types. .PARAMETER ExpandDepth Defines up till what level the collections will be expanded in the output. * A `-ExpandDepth 0` will create a single line expression. * A `-ExpandDepth -1` will compress the single line by removing command spaces. > [!Note] > White spaces (as newline characters and spaces) will not be removed from the content > of a (here) string. .PARAMETER Explicit By default, restricted language types initializers are suppressed. When the `Explicit` switch is set, *all* values will be prefixed with an initializer (as e.g. `[Long]` and `[Array]`) > [!Note] > The `-Explicit` switch can not be used in **restricted** language mode .PARAMETER FullTypeName In case a value is prefixed with an initializer, the full type name of the initializer is used. > [!Note] > The `-FullTypename` switch can not be used in **restricted** language mode and will only be > meaningful if the initializer is used (see also the [-Explicit] switch). .PARAMETER HighFidelity If the `-HighFidelity` switch is supplied, all nested object properties will be serialized. By default the fidelity of an object expression will end if: 1) the (embedded) object is a leaf node (see: [PSNode Object Parser][1]) 2) the (embedded) object expression is able to round trip. An object is able to roundtrip if the resulted expression of the object itself or one of its properties (prefixed with the type initializer) can be used to rebuild the object. The advantage of the default fidelity is that the resulted expression round trips (aka the object might be rebuild from the expression), the disadvantage is that information hold by less significant properties is lost (as e.g. timezone information in a `DateTime]` object). The advantage of the high fidelity switch is that all the information of the underlying properties is shown, yet any constrained or full object type will likely fail to rebuild due to constructor limitations such as readonly property. > [!Note] > Objects properties of type `[Reflection.MemberInfo]` are always excluded. .PARAMETER ExpandSingleton (List or map) collections nodes that contain a single item will not be expanded unless this `-ExpandSingleton` is supplied. .PARAMETER IndentSize Specifies indent used for the nested properties. .PARAMETER MaxDepth Specifies how many levels of contained objects are included in the PowerShell representation. The default value is define by the PowerShell object node parser (`[PSNode]::DefaultMaxDepth`). .LINK [1]: https://github.com/iRon7/ObjectGraphTools/blob/main/Docs/ObjectParser.md "PowerShell Object Parser" [2]: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_language_modes "About language modes" #> function ConvertTo-Expression { [CmdletBinding()][OutputType([String])] param( [Parameter(Mandatory = $true, ValueFromPipeLine = $True)] $InputObject, [ValidateScript({ $_ -ne 'NoLanguage' })] [PSLanguageMode]$LanguageMode = 'Restricted', [Alias('Expand')][Int]$ExpandDepth = [Int]::MaxValue, [Switch]$Explicit, [Switch]$FullTypeName, [Switch]$HighFidelity, [Switch]$ExpandSingleton, [String]$Indent = ' ', [Alias('Depth')][int]$MaxDepth = [PSNode]::DefaultMaxDepth ) begin { function StopError($Exception, $Id = 'IncorrectArgument', $Group = [Management.Automation.ErrorCategory]::SyntaxError, $Object){ if ($Exception -is [System.Management.Automation.ErrorRecord]) { $Exception = $Exception.Exception } elseif ($Exception -isnot [Exception]) { $Exception = [ArgumentException]$Exception } $PSCmdlet.ThrowTerminatingError([System.Management.Automation.ErrorRecord]::new($Exception, $Id, $Group, $Object)) } if ($this.LanguageMode -eq 'NoLanguage') { Throw 'The language mode "NoLanguage" is not supported.' } if (-not ('ConstrainedLanguage', 'FullLanguage' -eq $LanguageMode)) { if ($Explicit) { StopError 'The Explicit switch requires Constrained - or FullLanguage mode.' } if ($FullTypeName) { StopError 'The FullTypeName switch requires Constrained - or FullLanguage mode.' } } } process { $Node = [PSNode]::ParseInput($InputObject, $MaxDepth) [PSSerialize]::new( $Node, $LanguageMode, $ExpandDepth, $Explicit, $FullTypeName, $HighFidelity, $ExpandSingleton, $Indent ) } } |