src/IsConstAst.ps1
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<#
function ShowAst($Ast) { function Mapper($Ast) { $Ast.GetType().Name | Out-Host $Ast | Out-Host return $false } $Ast.Find($function:Mapper, $true) } function ShowAstOfExpr($Expr) { $Ast = [System.Management.Automation.Language.Parser]::ParseInput($Expr, [ref]$null, [ref]$null) ShowAst $Ast } #> param( [Parameter(Mandatory = $true)] $Ast ) $script:ConstCommands = @('Write-Host', 'echo', 'Write-Output', 'Write-Debug', 'Write-Information') $script:ConstVariables = @('?', '^', '$', 'args', 'Error', 'false', 'IsCoreCLR', 'IsLinux', 'IsMacOS', 'IsWindows', 'null', 'true') $script:EffectVariables = @('ConfirmPreference', 'DebugPreference', 'EnabledExperimentalFeatures', 'ErrorActionPreference', 'ErrorView', 'ExecutionContext', 'FormatEnumerationLimit', 'HOME', 'Host', 'InformationPreference', 'input', 'MaximumHistoryCount', 'MyInvocation', 'NestedPromptLevel', 'OutputEncoding', 'PID', 'PROFILE', 'ProgressPreference', 'PSBoundParameters', 'PSCommandPath', 'PSCulture', 'PSDefaultParameterValues', 'PSEdition', 'PSEmailServer', 'PSGetAPI', 'PSHOME', 'PSNativeCommandArgumentPassing', 'PSNativeCommandUseErrorActionPreference', 'PSScriptRoot', 'PSSessionApplicationName', 'PSSessionConfigurationName', 'PSSessionOption', 'PSStyle', 'PSUICulture', 'PSVersionTable', 'PWD', 'ShellId', 'StackTrace', 'VerbosePreference', 'WarningPreference', 'WhatIfPreference', 'WhatIfPreference') function IsNotConstAstNode($Ast) { if($Ast -is [System.Management.Automation.Language.CommandAst]) { if($script:ConstCommands -notcontains $Ast.CommandElements[0].Value) { return $true } } elseif ($Ast -is [System.Management.Automation.Language.VariableExpressionAst]) { if($script:ConstVariables -notcontains $Ast.VariablePath.UserPath) { return $true } } elseif ($Ast -is [System.Management.Automation.Language.FunctionDefinitionAst]) { $script:ConstCommands += $Ast.Name $script:ConstVariables += "function:$($Ast.Name)" } elseif ($Ast -is [System.Management.Automation.Language.AssignmentStatementAst]) { if($script:EffectVariables -notcontains $Ast.Left.VariablePath) { $script:ConstVariables += $Ast.Left.VariablePath.UserPath } } elseif ($Ast -is [System.Management.Automation.Language.NamedBlockAst]) { $ConstCommandsBackup = $script:ConstCommands $ConstVariablesBackup = $script:ConstVariables foreach ($Statement in $Ast.Statements) { if($null -ne $Statement.Find($function:IsNotConstAstNode, $true)) { return $true } } $script:ConstCommands = $ConstCommandsBackup $script:ConstVariables = $ConstVariablesBackup } return $false } $result=$null -eq $Ast.Find($function:IsNotConstAstNode, $true) Remove-Variable -Name @('ConstCommands', 'ConstVariables', 'EffectVariables') -Scope Script return $result |