regex - 如何在我的替换语句中检索 powershell 中对象的值？

Question

尝试使用对象映射将月份名称替换为月份编号。用例是我正在尝试重命名包含月份名称的文件。

$monthNameToNumberMap = @{
  January = '01'
  February = '02'
  March = '03'
  April = '04'
  May = '05'
  June = '06'
  July = '07'
  August = '08'
  September = '09'
  October = '10'
  November = '11'
  December = '12'
}

Write-Host "Desired : 02 20 => ";
"February 20" -Replace '([A-z]{3,9}) (\d{2})', "$monthNameToNumberMap[`$1] `$2"

Write-Host "Desired : 05 03 => ";
"May 03" -Replace '([A-z]{3,9}) (\d{2})', "$monthNameToNumberMap[`$1] `$2"

# receiving : @{January=01; February=02; March=03; April=04; May=05; June=06; July=07; August=08; September=09; October=10; November=11; December=12}[February] 20

我无法使用正则表达式匹配组访问对象映射的值。

Answer 1

您正在尝试评估字符串替换模式内的反向引用值，这是不可能的。您需要定义一个回调并将其传递给 [regex]::Replace 方法:

$regex = [regex]'\b([A-Za-z]{3,}) (\d{2})\b'
$callback = {  param($m) $monthNameToNumberMap[$m.Groups[1].Value] + " " + $m.Groups[2].Value }
$regex.Replace("February 20", $callback)

请注意[A-z] matches more than just letters ，因此，建议使用[a-zA-Z]。

我还添加了单词边界以避免匹配诸如 AAAAAAAAAA 2222222222222222 之类的字符串。