Created
March 24, 2016 14:19
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Powershell Concept for Reverse Polish Notation
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#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, /, *' |
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