Powershell Concept for Reverse Polish Notation

Solve-RPN.ps1

#Powershell concept for Revese Polish Notation
#Based on ealier JS and Java variants: http://codepen.io/xainey/pen/ojbZdj

function Solve-RPN
{
    [CmdletBinding()]
    [OutputType([System.Double])]
    param
    (        
        [parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string] $expression,

        [parameter(Mandatory = $false)]
        [string] $delimeter = ' '
    )

    $biOps = "+-*/^"

    $pieces = $expression.ToLower() -split $delimeter

    $s = new-object  System.Collections.Stack  

	foreach ($e in $pieces)
	{
		if (isNumeric -str $e)
		{
			$s.Push([double] $e)
			continue
		}

		if ($s.Count -eq 0)
		{
			throw "Error"
		}

		if ( $biOps.Contains($e) )
		{
			$s.Push((biOperation -e $e -b $s.pop() -a $s.pop()))
			continue
		}

		$s.Push((singleOperation -e $e -a $s.pop()));
	}

	return $s.pop()
}


function singleOperation
{
    [CmdletBinding()]
    [OutputType([System.Double])]
    param
    (
        [ValidateSet("sqrt", "exp", "sin", "cos", "tan", "asin", "acos", "atan")]
        [string] $e,
        
        [parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [double] $a
    )

    if ($e.Equals("sqrt")){return [math]::Sqrt($a)}
    if ($e.Equals("exp") ){return [math]::Exp($a) }
    if ($e.Equals("sin") ){return [math]::Sin($a) }
    if ($e.Equals("cos") ){return [math]::Cos($a) }
    if ($e.Equals("tan") ){return [math]::Tan($a) }
    if ($e.Equals("asin")){return [math]::Asin($a)}
    if ($e.Equals("acos")){return [math]::Acos($a)}
    if ($e.Equals("atan")){return [math]::Atan($a)}
	
	return 0;
}

function biOperation
{
    [CmdletBinding()]
    [OutputType([System.Double])]
    param
    (
        [ValidateSet("+", "-", "*", "/", "^")]
        [string] $e,
        
        [parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [double] $a,
        
        [parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [double] $b
    )

	if ($e.equals("+")){return $a + $b}
	if ($e.equals("-")){return $a - $b}
	if ($e.equals("*")){return $a * $b}
	if ($e.equals("/")){return $a / $b}
	if ($e.equals("^")){return [math]::Pow($a, $b)}

	return 0;
}


function isNumeric
{
    [CmdletBinding()]
    [OutputType([System.Boolean])]
    param
    (        
        [parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string] $str
    )

	try
	{
		[double] $str
	}
	catch
	{
		return $false
	}
	
    return $true
}


Solve-RPN -expression "2 5 *"
Solve-RPN -delimeter ', ' -expression '1.52, 1, 1.52, /, -, 0.5, *, 3.14285, 90, /, -1.66, *, SIN, 4.29125, *, *, ATAN, 180.0, 3.14285, /, *'