StringBase.class.ps1 - string-parsing base class example

StringBase.class.ps1

class StringBase {
    hidden static [string] $_pattern = '(?!)'
    hidden [string] $_value

    # define single ctor with input string as its only parameter
    StringBase([string]$value) {
        $this._value = $value
        if (-not $this.TryParse()) {
            throw [ArgumentException]::new("Failed to parse input string '$value'", 'value')
        }
    }

    # define parsing routine
    hidden [bool]
    TryParse() {
        # use runtime type to discover (non-hidden) properties on derived types
        $targetProperties = $this.GetType().GetProperties() |Where-Object { -not $_.GetCustomAttributes([System.Management.Automation.HiddenAttribute]) } |ForEach-Object Name
        # construct pattern from static property on derived type
        $pattern = [regex]::new($this::_pattern)
        if (($match = $pattern.Match($this._value)).Success) {
            # success, let's map group captures to class properties
            $match.Groups |Where-Object { $_.Name -in $targetProperties -and $_.Success } |ForEach-Object {
                $this.$($_.Name) = $_.Value
            }
        }
        # indicate whether parsing succeeded
        return $match.Success
    }
}


<#
  Example usage:
    [ContactCard]'michael32 <[email protected]>'
#>
class ContactCard : StringBase {
  hidden static [string] $_pattern = '^(?<Name>.*?)\s*<(?<Email>.*)>$'
  [string]$Name
  [string]$Email

  ContactCard($value) : base($value) {}
}


<#
  Example usage:
    [LogMessage]"[$(Get-Date -f o)] INFO Hello there!"
#>
class LogMessage : StringBase {
    hidden static [string] $_pattern = '^\[(?<When>.*?)\] (?<Severity>INFO|WARN|CRIT) (?<Message>.*)$'
    [DateTime]$When
    [string]$Severity
    [string]$Message

    LogMessage($value) : base($value) {}
}