Invoke-Equation.ps1
|
function Invoke-Equation { <# .Synopsis Invokes a PowerShell script for an equation .Description Writes a PowerShell script for an equation. To make sure that this is safe, you can only do the following things inside of a script. Use static methods from the [Math] class. Use constant numbers Use the following operators '=','+', '-','-lt', '*', '-gt','-lt', '-ge','-le', '-ne', '-eq', '%', '/' .Example Invoke-Equation -Step { # Square A $aSquared = $a * $a # Square B $bSquared = $b * $b # Get the square root of the values [Math]::Sqrt($aSquared + $bSquared) } #> param( # The list of steps. Each step's comments will become [ScriptBlock[]] $Step, # The name of the equation. If not directly set, the equation name will become the name of the parent function [string]$EquationName, # If set, waits this amount of time between each step [Timespan]$WaitBetweenStep ) process { #Region Filter out Bad Scripts $ok = $true foreach ($scriptBlock in $step) { $tokens = @([Management.Automation.PSParser]::Tokenize($step, [ref]$null)) for ($i =0 ;$i -lt $tokens.Count; $i++) { $Token = $tokens[$i] if ($token.Type -eq 'Command') { Write-Error "Cannot use commands in the filter" $ok = $false break } if ($token.Type -eq 'Keyword') { if ('if', 'else', 'elseif' -contains $token.Content) { } Write-Error "Cannot use keywords in the filter" $ok = $false break } if ($token.Type -eq 'String') { Write-Error "No Strings allowed" $ok = $false break } if ($token.Type -eq 'Type' -and ($token.Content -ne '[Math]' -and $token.Content -ne 'Math')) { Write-Error "Can only use the [Math] class in equations" $ok = $false break } if ($token.Type -eq 'Type') { # Make sure the next item is a static member refrence if ($i -eq ($tokens.Count - 1)) { Write-Error "May only use methods from [Math]" $ok = $false break } else { $i++ } } if ($token.Type -eq 'GroupStart' -and ('(','{' -notcontains $token.Content)) { Write-Error "Only Parenthesis are allowed in equations" $ok = $false break } if ($token.Type -eq 'GroupEnd' -and (')','}' -notcontains $token.Content)) { Write-Error "Only Parenthesis are allowed in equations" $ok = $false break } if ($token.Type -eq 'Variable' -or $Token.Type -eq 'Number' -or $token.Type -eq 'GroupEnd') { if (! $tokens[$i +1]) { break } $nextToken = $tokens[$i + 1] $validOperators = '=','+', '-','-lt', '*', '-gt','-lt', '-ge','-le', '-ne', '-eq', '%', '/' if (($nextToken.Type -ne 'Operator' -and $validOperators -notcontains $nextToken.Type) -and ( $nextToken.Type -ne 'Newline' ) -and ( $nextToken.Type -ne 'GroupEnd' )) { Write-Error "`$$($token.Content) must be followed by one of the following operators $validOperators" $ok = $false } else { $i = $i + 1 } } if ($token.Type -eq 'Operator') { $validOperators = '=','+', '-','-lt', '*', '-gt','-lt', '-ge','-le', '-ne', '-eq', '%', '/' if ($validOperators -notcontains $token.Content) { Write-Error "Unexpected Operator $($token.Content) ($($token.StartLine.ToString() +','+ $token.StartColumn)))" $ok = $false break } } } foreach ($token in $tokens) { if ($token.Type -eq 'Number') { if (! $foreach.MoveNext()) { break } $validOperators = '=','+', '-','-lt', '*', '-gt','-lt', '-ge','-le', '-ne', '-eq', '%', '/' if (($foreach.current.Type -ne 'Operator' -and $validOperators -notcontains $foreach.current.Content) -and ( $foreach.current.Type -ne 'Newline' ) -and ( $foreach.current.Type -ne 'GroupEnd' )) { Write-Error "`$$($token.Content) must be followed by one of the following operators $validOperators" $ok = $false } } if ($token.Type -eq 'GroupEnd') { if (! $foreach.MoveNext()) { break } $validOperators = '=','+', '-','-lt', '*', '-gt','-lt', '-ge','-le', '-ne', '-eq', '%', '/' if (($foreach.current.Type -ne 'Operator' -and $validOperators -notcontains $foreach.current.Content) -and ( $foreach.current.Type -ne 'Newline' ) -and ( $foreach.current.Type -ne 'GroupEnd' )) { Write-Error "`$$($token.Content) must be followed by one of the following operators $validOperators" $ok = $false } } } } if (-not $Ok) { return } #Endregion Filter out Bad Scripts #region Combine Scripts and get steps/explanations $text = $combinedScript = $step -join ([Environment]::NewLine) $tokens = [Management.Automation.PSParser]::Tokenize($combinedScript, [ref]$null) $work = & { $lastResult = @{Explanation=""} foreach ($token in $tokens) { if ($token.Type -eq "Newline") { continue } if ($token.Type -ne "Comment" -or $token.StartColumn -gt 1) { $isInContent = $true if (-not $lastToken) { $lastToken = $token } } else { if ($lastToken.Type -ne "Comment" -and $lastToken.StartColumn -eq 1) { $chunk = $text.Substring($lastToken.Start, $token.Start - 1 - $lastToken.Start) $lastResult.Script = [ScriptBlock]::Create($chunk) # mutliparagraph, split up the results if multiparagraph $paragraphs = @() $lastResult.Explanation = $lastResult.Explanation.trim() New-Object PSObject -Property $lastResult $null = $paragraphs $lastToken = $null $lastResult = @{Explanation="";} $isInContent = $false } } if (-not $isInContent) { $lines = $token.Content.Trim("<>#") $lines = $lines.Split([Environment]::NewLine, [StringSplitOptions]"RemoveEmptyEntries") foreach ($l in $lines) { switch ($l) { default { $lastResult.Explanation += ($l + [Environment]::NewLine) } } } } } if ($lastToken -and $lastResult) { $chunk = $text.Substring($lastToken.Start) $lastResult.Explanation = $lastResult.Explanation.trim() $lastResult.Script = [ScriptBlock]::Create($chunk) New-Object PSObject -Property $lastResult } elseif ($lastResult) { $lastResult.Explanation = $lastResult.Explanation.trim() New-Object PSObject -Property $lastResult } } #endregion Combine Scripts and get steps/explanations #region Determine Equation Name if (-not $psBoundParameters.ContainsKey('EquationName')) { $EquationName = Get-PSCallStack | Select-Object -Skip 1 -First 1 -ExpandProperty Command } #endregion Determine Equation Name #region Walk thru the equation $totalStepCount = @($work).Count foreach ($equationStep in $work) { Write-Progress "$EquationName " "$($equationStep.Explanation)" $stepNumber++ $stepResult = New-Object PSObject -Property @{ Number = $stepNumber Step = "$($equationStep.Explanation)" Script = $equationStep.Script Result = . $equationStep.Script } if ($stepResult.Result -eq $null) { $tokens =[MAnagement.Automation.PSParser]::Tokenize( $equationStep.Script, [ref]$null) for ($i =0; $i -lt $tokens.Count; $i++) { $t = $tokens[$i] if ($t.Type -eq 'NewLine') { continue } if ($t.Type -eq 'Variable') { $next = $tokens[$i+1] if ($next.Type -eq 'Operator' -and ('=', '+=', '-=', '/=', '*=', '%=' -contains $next.Content)) { $stepResult.Result = Invoke-Expression "`$$($t.Content)" } } } } $null =$stepResult.pstypenames.Clear() $null = $stepResult.pstypenames.add('MathStep') if ($showWork) { $stepResult } if ($stepNumber -eq $totalStepCount) { if ($showWork) { $result = New-Object PSOBject -Property @{ Number = $stepNumber + 1 Step = "Done" Script = "" Result = $stepResult.Result } $null = $result.pstypenames.Clear() $null = $result.pstypenames.add('MathResult') $result } else { $stepResult.Result } } if ($waitBetweenStep -and $waitBetweenStep.TotalMilliseconds) { Start-Sleep -Milliseconds $WaitBetweenStep.TotalMilliseconds } } #endregion } } |