functions/filter/New-PSFFilter.ps1

function New-PSFFilter
{
<#
    .SYNOPSIS
        Creates a new filter object.
     
    .DESCRIPTION
        Creates a new filter object based off the specified expression.
        Optionally, an associated condition set can be specified, either as object or by name and module.
        Conditions Set contain the implementation of the condition logic, that will be used when evaluating the filter expression.
     
        These filter objects can then be used to execute validation either statically or against input objects.
        Combined with filter conditions and condition sets, filters allow defining a custom filter syntax that is easy to write humanly readable filter expressions for without exposing direct code execution.
        This makes filter expressions suitable for data regions and makes conditions easily reusable.
     
    .PARAMETER Expression
        The expression to build a filter object for.
        Can only consist of:
        - Names of conditions: Words (may contain letters, numbers and underscore, but no dash)
        - Parenthesis
        - Logical operators (-or, -and, -not, -xor)
     
    .PARAMETER ConditionSet
        A condition set object to attach to the filter.
     
    .PARAMETER SetModule
        The name of the module from which to select the condition set to attach to the filter.
     
    .PARAMETER SetName
        The name of the condition set to attach to the filter.
     
    .EXAMPLE
        PS C:\> New-PSFFilter -Expression 'OSWindows -or EnvAzurePipelines'
     
        Creates a filter object around the "OSWindows -or EnvAzurePipelines" expression.
     
    .EXAMPLE
        PS C:\> New-PSFFilter -Expression 'OSWindows -or EnvAzurePipelines' -SetModule PSFramework -SetName Environment
     
        Creates a filter object around the "OSWindows -or EnvAzurePipelines" expression.
        It then attaches the latest version of the Environment ConditionSet from within the PSFramework module.
#>

    [OutputType([PSFramework.Filter.Expression])]
    [CmdletBinding(DefaultParameterSetName = 'default')]
    param (
        [Parameter(Mandatory = $true)]
        [string]
        $Expression,
        
        [Parameter(Mandatory = $true, ParameterSetName = 'Object')]
        [PSFramework.Filter.ConditionSet]
        $ConditionSet,
        
        [Parameter(Mandatory = $true, ParameterSetName = 'Name')]
        [PsfArgumentCompleter('PSFramework.Filter.SetModule')]
        [string]
        $SetModule,
        
        [Parameter(Mandatory = $true, ParameterSetName = 'Name')]
        [PsfArgumentCompleter('PSFramework.Filter.SetName')]
        [string]
        $SetName
    )
    
    process {
        $conditionSetObject = $null
        if ($ConditionSet -or $SetName) {
            $conditionSetObject = Resolve-PsfFilterConditionSet -ConditionSet $ConditionSet -SetModule $SetModule -SetName $SetName -Cmdlet $PSCmdlet
        }
        
        try { New-Object PSFramework.Filter.Expression($Expression, $conditionSetObject) }
        catch { $PSCmdlet.ThrowTerminatingError($_) }
    }
}