Public/ConvertFrom-Unicode.ps1
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<# .SYNOPSIS Convert any Unicode data (string) to its ASCII equivalent. .DESCRIPTION ConvertFrom-Unicode checks the input char by char and tries the conversion to an ASCII equivalent char if possible. The length of the input and output can differ, as chars can be discarded if they fall e.g. under the unicode private range. .PARAMETER InputObject Data to be converted to ASCII .PARAMETER DACH Specifies if a conversion by the standard of Germany/Switzerland/Austria is desired. This changes the behavior from e.g. ä->a to ä->ae. .PARAMETER RemoveNonAlphabeticChars Removes any character from the converted output not being an alphabetic char. .EXAMPLE ConvertFrom-Unicode -InputObject "Testä__" Testa__ .EXAMPLE ConvertFrom-Unicode -InputObject "Testä__" -RemoveNonAlphabeticChars Testa .EXAMPLE ConvertFrom-Unicode -InputObject "Testä__" -DACH -RemoveNonAlphabeticChars Testae .NOTES Use with care. No guarantees of functionality are made. If you want to specify custom behavior, just alter the files underneath /lib. #> function ConvertFrom-Unicode { [CmdletBinding()] [OutputType([String])] param( [Parameter(Mandatory, ValueFromPipeline)] [Char[]] $InputObject, [Switch] $DACH, [Switch] $RemoveNonAlphabeticChars ) Begin { #Lib Directory. [String] $rootDirectory = ( $MyInvocation.MyCommand.Module.Path -replace $MyInvocation.MyCommand.Module.RootModule ) [String] $dataDirectory = Join-Path -Path $rootDirectory -ChildPath "lib" #Used for caching sections. $sectionCache = @{ } ##Basic ASCII $asciiEnd = 127 #Ignore values over 0xeffff $extremeValues = 983039 #Ignore https://en.wikipedia.org/wiki/Private_Use_Areas <# 0x0E000 - 0x0F8FF 57344 - 63743 #> $privateRange = @(57344, 63743) #Ignore https://docs.microsoft.com/en-us/windows/desktop/intl/surrogates-and-supplementary-characters $supplementaryRange = @(55296, 57343) #DACH conversions [hashtable] $lowerConversion = @{ [char] 'ä' = "ae" [char] 'ü' = "ue" [char] 'ö' = "oe" [char] 'ß' = "ss" } [hashtable] $upperConversion = @{ [char] 'Ä' = "Ae" [char] 'Ü' = "Ue" [char] 'Ö' = "Oe" } } Process { #End Result. [String] $returnValue = [String]::Empty #Loop through all chars inside string. foreach ( $char in $InputObject ) { $ordinalValue = [Int][Char]$char if ( $ordinalValue -gt $extremeValues ) { Write-Error -Message ("{0} - ordinalValue is out of Range" -f $ordinalValue) continue } if ( $ordinalValue -ge $privateRange[0] -and $ordinalValue -le $privateRange[1] ) { Write-Error -Message ("{0} - ordinalValue is in private use Range" -f $ordinalValue) continue } if ( $ordinalValue -ge $supplementaryRange[0] -and $ordinalValue -le $supplementaryRange[1] ) { Write-Error -Message ("{0} - ordinalValue is supplementary character and will be skipped" -f $ordinalValue) continue } #ASCII can stay ASCII. if ( $ordinalValue -le $asciiEnd ) { $returnValue += $char continue } #-- DACH if ($DACH.IsPresent) { if ($lowerConversion.ContainsKey($char)) { $returnValue += $lowerConversion.Item($char) continue } if ($upperConversion.ContainsKey($char)) { $returnValue += $lowerConversion.Item($char) continue } } #-- #Pad If needed $hexValue = ([Convert]::ToString($ordinalValue, 16)).PadLeft(5, "0") $decodeSection = $hexValue.Substring(0, 3) $decodeCharKey = [Convert]::ToInt32($hexValue.Substring(3, 2), 16) if ( -not $sectionCache.ContainsKey($decodeSection) ) { [hashtable] $keyTable = Import-PowerShellDataFile -Path ("{0}\x{1}.ignore" -f $dataDirectory, $decodeSection) $sectionCache.Add($decodeSection, $keyTable.data) } $conversionList = $sectionCache.Item($decodeSection) $returnValue += $conversionList[$decodeCharKey] } if ( $RemoveNonAlphabeticChars.IsPresent ) { $alphString = [String]::Empty foreach ( $char in $returnValue[0..($returnValue.Length - 1)] ) { $charValue = [byte][char]$char ##space if ( ( $charValue -ge 65 -and $charValue -le 90 ) -or ( $charValue -ge 97 -and $charValue -le 122 ) ) { #ascii char all fine } else { $char = "" } ##valid $alphString += $char } $returnValue = $alphString } return $returnValue } } |