How to combine multiple .net regex into one?

Question

var keyList = new[] { "AccountKey", "PrivateKey", "APIKey", "DefectiveKeyGracefulExpiration" };
var multiplePatternMatching = string.Format("({0})", string.Join("|", keyList));
var keyRegex = string.Format(@"(?s)<([\s<]?{0}[\s<]*)>.*?</\1>", multiplePatternMatching);

And I have another regex:

var passwordRegex = @"(?si)<([^\s<]*password[^\s<]*)>.*?</\1>";

How to combine keyRegex and passwordRegex into one regex? I known that I need to use | but I don't know how.

I'm trying to use | like this:

var keyOrPasswordRegex = string.Format( @"(?s)<([\s<]?{0}[\s<]*)>.*?</\1>|(?si)<([^\s<]*password[^\s<]*)>.*?</\2>", multiplePatternMatching);

but it's doesnt work

Input:

<job xmlns:i="..." xmlns="...">
<password>asdfasdf</password>
<adminPassword>asd</adminPassword>
<AccountKey>asd</AccountKey>
<AccountKeyZ>asd</AccountKeyZ>
...</job>

Actual result:

<job xmlns:i="..." xmlns="...">
 <></>
 <></>
<AccountKey></AccountKey>
<AccountKeyZ>asd</AccountKeyZ>
...</job>

Expected result:

<job xmlns:i="..." xmlns="...">
<password></password>
<adminPassword></adminPassword>
<AccountKey></AccountKey>
<AccountKeyZ>asd</AccountKeyZ>
...</job>

Already answered here: http://stackoverflow.com/questions/869809/combine-regexp — Pedro G. Dias, Mar 21 '16 at 18:51
I think you have a problem with a backreference here, you need to be careful not to break the order of capturing groups. Use `var multiplePatternMatching = string.Format("(?:{0})", string.Join("|", keyList)); var keyRegex = string.Format(@"(?s)<([^\s<]*{0}[^\s<]*)>.*?\1>", multiplePatternMatching);` — Wiktor Stribiżew, Mar 21 '16 at 19:08
@WiktorStribiżew thanks, and how to combine `keyRegex` with `passwordRegex` ? — Anatoly, Mar 21 '16 at 19:11
@WiktorStribiżew No, because `password` it's completely different regex — Anatoly, Mar 21 '16 at 19:20
Without examples, it is not possible to help you more. `<([\s<]?{0}[\s<]*)>.*?\1>` makes no sense. — Wiktor Stribiżew, Mar 21 '16 at 19:31
I am putting my children to bed, I will have a look in half an hour. — Wiktor Stribiżew, Mar 21 '16 at 19:46
Thanks, the problem is that my `passwordRegex` is with `i` and `^`, `keyRegex` without. And `passwordRegex` have `*password` and `keyRegex` have `?{0}` — Anatoly, Mar 21 '16 at 19:48
Ok, I see that key regex means a regex for tags that include `key` word and their content must be reset. Try `Regex.Replace(input, @"(?si)<([^\s<]*password[^\s<]*|(?:AccountKey|PrivateKey|APIKey|DefectiveKeyGracefulExpiration))>.*?\1>", "<$1>$1>")`. **See [this demo](http://ideone.com/ks55aM).** — Wiktor Stribiżew, Mar 21 '16 at 22:00
@WiktorStribiżew Thank you very much! You save my live! It works! Set your answer not in the comment if you want — Anatoly, Mar 22 '16 at 08:50

score 2 · Accepted Answer · answered Mar 22 '16 at 09:11

You need an alternation like this:

var keyList = new[] { "AccountKey", "PrivateKey", "APIKey", "DefectiveKeyGracefulExpiration" };
var multiplePatternMatching = string.Format("({0})", string.Join("|", keyList));
var rx = string.Format(@"(?si)<([^\s<]*password[^\s<]*|{0})>.*?</\1>", multiplePatternMatching);
Console.WriteLine(Regex.Replace(s, rx, "<$1></$1>"));

See the IDEONE demo and a regex demo. Explanation:

< - a literal <
([^\s<]*password[^\s<]*|{0}) - (Group 1) 0+ characters other than whitespace and < followed with a word password and followed with 0+ characters other than whitespace and < or an alternation group of AccountKey, PrivateKey, APIKey or DefectiveKeyGracefulExpiration (those listed in the multiplePatternMatching variable)
> - a literal >
.*?</\1> - any 0+ symbols, as few as possible, up to the first </ followed with the contents of the first capture group and >.

How to combine multiple .net regex into one?

1 Answers1