【powershell】正規表現でマッチした文字をハイライト表示する（ ANSI エスケープシークエンスの利用）

powershell では以前に書いた Write-Host とループによる方法 のほかにエスケープシークエンスでも標準出力の色を変更できるようです。

環境

Name                           Value
----                           -----
PSVersion                      5.1.18362.752
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.18362.752
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

コード

Microsoft.PowerShell_profile.ps1

function New-AnsiColorObject {
    $decimalColor = @{
        Black       = "0"
        Red         = "1"
        Green       = "2"
        Yellow      = "11"
        Blue        = "4"
        Magenta     = "5"
        Cyan        = "6"
        White       = "15"
        Gray        = "7"
        DarkRed     = "124"
        DarkGreen   = "22"
        DarkYellow  = "100"
        DarkBlue    = "17"
        DarkMagenta = "124"
        DarkCyan    = "31"
        DarkGray    = "8"
    }
    $fgTable = @{}
    $bgTable = @{}
    $decimalColor.GetEnumerator() | ForEach-Object {
        $fgTable[$_.Name] = "$([char]27)[38;5;{0}m" -f $_.Value
        $bgTable[$_.Name] = "$([char]27)[48;5;{0}m" -f $_.Value
    }
    return [PSCustomObject]@{
        FG = $fgTable
        BG = $bgTable
        RESET = "$([char]27)[0m"
    }
}
$Global:ANSI_ESC_SEQ = New-AnsiColorObject

function Write-StringHighLight {
    param (
        [string]$pattern = ".",
        [switch]$case,
        [ValidateSet("White", "Black", "Blue", "DarkBlue", "Green", "DarkGreen", "Cyan", "DarkCyan", "Red", "DarkRed", "Magenta", "DarkMagenta", "Yellow", "DarkYellow", "Gray", "DarkGray")][string]$color = "Yellow",
        [switch]$continuous
    )

    $option = ($case)? "None" : "IgnoreCase"
    foreach ($line in $input) {
        [regex]::Replace(
            $line,
            "($pattern)",
            ($Global:ANSI_ESC_SEQ.BG[$color] + $Global:ANSI_ESC_SEQ.FG.Black + '$1' + $Global:ANSI_ESC_SEQ.RESET),
            $option) | Write-Host -NoNewline:$continuous
    }
}
Set-Alias hilight Write-StringHighLight

かなりスッキリ書き直せました。powershell 7 以降であれば [char]27 の代わりに `e が使えるようです（公式ドキュメント）。