Regex non capturing group

Question

Regex Experts. I need some help to capture the IP address and its status from the below HTML string.

$html = "<div><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Active Zone : BW Zone 1[1], &nbsp;&nbsp;VIP = 192.168.254.10</div>

<div><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a href=https://192.168.254.10/checkGlobalReplicationTier>https://192.168.254.10/checkGlobalReplicationTier</a>
&nbsp;&nbsp;[ACTIVE]</div>
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a href=https://192.168.254.10/checkReplication>https://192.168.254.10/checkReplication</a></div>
<div><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a href=https://192.168.254.11/checkGlobalReplicationTier>https://192.168.254.11/checkGlobalReplicationTier</a>
&nbsp;&nbsp;[STANDBY]</div>
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a href=https://192.168.254.11/checkReplication>https://192.168.254.11/checkReplication</a></div>
<div><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Local Zones:</div>
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; LC Zone 3[3], &nbsp;&nbsp;VIP = 192.168.254.13
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a href=https://192.168.254.13/checkReplication>https://192.168.254.13/checkReplication</a>
&nbsp;&nbsp;[ACTIVE]</div>"

[regex]::matches($html, '((\d{1,3}\.){3}\d{1,3})((?s).*?)((?<=\[)[A-z]*(?=\]))').value

The above regex is able to get the IP and Status.. but i want to omit everything in-between the IP and Status. How do i do this with non capturing regex.

192.168.254.10  Active
192.168.254.11  Standby
192.168.254.13  Active

Do you mean non capturing as in capture groups or non matching in the regex match? if you meant non capturing groups then all you have to do is add `?:` to the third capturing group in your expression. It would become: `((\d{1,3}\.){3}\d{1,3})(?:(?s).*?)((?<=\[)[A-z]*(?=\]))` — anotherGatsby, Apr 13 '22 at 09:11

iRon · Answer 1 · 2022-04-14T11:40:58.467

It is generally a bad idea to attempt to parse HTML with regular expressions.
Instead use a dedicated HTML parser as the HtmlDocument class (and the Uri class for uri's).

Example

function ParseHtml($String) {
    $Unicode = [System.Text.Encoding]::Unicode.GetBytes($String)
    $Html = New-Object -Com 'HTMLFile'
    if ($Html.PSObject.Methods.Name -Contains 'IHTMLDocument2_Write') {
        $Html.IHTMLDocument2_Write($Unicode)
    } 
    else {
        $Html.write($Unicode)
    }
    $Html.Close()
    $Html
}

$Document = ParseHtml $Html
$Document.getElementsByTagName('div') |ForEach-Object {
    if ($_.lastChild.nodeValue -match '\[(?<Status>ACTIVE|STANDBY)\]') {
        [pscustomobject]@{
            Ip     = ([Uri]$($_.getElementsByTagName('a')).href).Host
            Status = $Matches.Status
        }
    }
}

Ip             Status
--             ------
192.168.254.10 ACTIVE
192.168.254.11 STANDBY
192.168.254.13 ACTIVE

score 0 · Accepted Answer · answered Apr 13 '22 at 13:41

Generally, consider iRon's helpful answer for robust HTML parsing with a dedicated parser.

How do i do this with non capturing regex.

You can't, because in order to exclude parts of the matching span of text you'd need look-around assertions (such as the negative look-behind assertions in your attempt, e.g. (?<=\[)), but these in turn prevent you from consuming the unwanted parts of the span.

Instead, use two capture groups and access them as follows:

[regex]::Matches(
  $html, 
  '(?s)((?:\d{1,3}\.){3}\d{1,3}).+?\[([A-Z]+)\]'
 ) | ForEach-Object { 
   [pscustomobject] @{ 
     Ip = $_.Groups[1].Value
     Status = $_.Groups[2].Value
   } 
 }

This results in the following display output:

Ip             Status
--             ------
192.168.254.10 ACTIVE
192.168.254.11 STANDBY
192.168.254.13 ACTIVE

Regex non capturing group

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