Individually selecting multiple strings using Ruby and regular expressions

Question

I have a string of data which looks like this which is on one line.

<record xmlns:f="http://abc.com/">
<f:Table><f:Row><f:Cell>#1</f:Cell></f:Row><f:Row><f:Cell>Data 222</f:Cell></f:Row><f:Row>           <f:Cell>Version: v3</f:Cell></f:Row><f:Row><f:Cell>Serial Number: 000000000</f:Cell></f:Row> <f:Row><f:Cell>Signature: 123</f:Cell></f:Row><f:Row><f:Cell>Issuer:</f:Cell></f:Row><f:Row> <f:Cell>C=EE,</f:Cell></f:Row><f:Row><f:Cell>ST=ABC,</f:Cell></f:Row><f:Row><f:Cell>L=avavv,</f:Cell></f:Row><f:Row><f:Cell><f:HexDump><f:Line seq=""0x0000"" hex=""09 09 4f 3d 5a 65 72 6f 54 75 72 6e 61 72 6f 75"">..O=ABC</f:Line><f:Line seq=""0x0010"" hex=""6e 64 20 4f c3 9c 2c"">nd OÇ.,</f:Line></f:HexDump></f:Cell></f:Row><f:Row><f:Cell>OU=abc,</f:Cell></f:Row><f:Row><f:Cell>CN=trtrtrtr,</f:Cell></f:Row><f:Row><f:Cell>E=null,</f:Cell></f:Row><f:Row><f:Cell>Create: 03/03/2010 14:58</f:Cell></f:Row><f:Row><f:Cell>Expire: 04/02/2010 14:58</f:Cell></f:Row><f:Row><f:Cell>Subject:</f:Cell></f:Row><f:Row><f:Cell>C=EE,</f:Cell></f:Row><f:Row><f:Cell>ST=SS,</f:Cell></f:Row><f:Row><f:Cell>L=Tartu,</f:Cell></f:Row><f:Row><f:Cell><f:HexDump><f:Line seq=""0x0000"" hex=""09 09 4f 3d 5a 65 72 6f 54 75 72 6e 61 72 6f 75"">..O=ZeroTurnarou</f:Line><f:Line seq=""0x0010"" hex=""6e 64 20 4f c3 9c 2c"">nd OÇ.,</f:Line></f:HexDump></f:Cell></f:Row><f:Row><f:Cell>OU=KKK,</f:Cell></f:Row></f:Table>

My Ruby Regular expresion looks like this:

<f:HexDump>[\s\S]*,<\/f:Line><\/f:HexDump>

So I'm trying to remove everything (including the tags) between both of the <f:HexDump> and <f:/HexDump> tags but leaving the stuff in between.

The problem is my regex is selecting everything in between right up to the second <f:/HexDump> tag.

<f:HexDump><f:Line seq=""0x0000"" hex=""09 09 4f 3d 5a 65 72 6f 54 75 72 6e 61 72 6f 75"">..O=ABC</f:Line><f:Line seq=""0x0010"" hex=""6e 64 20 4f c3 9c 2c"">nd OÇ.,</f:Line></f:HexDump></f:Cell></f:Row><f:Row><f:Cell>OU=abc,</f:Cell></f:Row><f:Row><f:Cell>CN=trtrtrtr,</f:Cell></f:Row><f:Row><f:Cell>E=null,</f:Cell></f:Row><f:Row><f:Cell>Create: 03/03/2010 14:58</f:Cell></f:Row><f:Row><f:Cell>Expire: 04/02/2010 14:58</f:Cell></f:Row><f:Row><f:Cell>Subject:</f:Cell></f:Row><f:Row><f:Cell>C=EE,</f:Cell></f:Row><f:Row><f:Cell>ST=SS,</f:Cell></f:Row><f:Row><f:Cell>L=Tartu,</f:Cell></f:Row><f:Row><f:Cell><f:HexDump><f:Line seq=""0x0000"" hex=""09 09 4f 3d 5a 65 72 6f 54 75 72 6e 61 72 6f 75"">..O=ZeroTurnarou</f:Line><f:Line seq=""0x0010"" hex=""6e 64 20 4f c3 9c 2c"">nd OÇ.,</f:Line></f:HexDump>

Can this be done using Ruby regular expressions?

That's XML. You should parse XML as XML using an XML parser, not as text using a regular expression. Especially when you want to match nested things. — Ry-
– Ry- ♦, Commented Sep 13, 2012 at 0:53
Yeah I know, I tried nokogiri but I've not had any success with getting to elements I need to remove. Probably because its badly formed. — user1513388
– user1513388, Commented Sep 13, 2012 at 0:56
You mean the ""? Luckily, that can be fixed with a string replacement :) (If it's not that, then what errors does nokogiri give you?) — Ry-
– Ry- ♦, Commented Sep 13, 2012 at 0:58
I don't really get an error as such. If I use this code: doc = Nokogiri::XML(doc2) doc.remove_namespaces! node_values = doc.search('//HexDump/*') do |n| n.text end puts node_values I can't get it to return anything. I did a string replacement and removed all of the "". — user1513388
– user1513388, Commented Sep 13, 2012 at 1:12
If your XML is malformed you're almost certainly more likely to get problems parsing it with regex than a proper XML parser. Malformed content is the #1 reason to use a parser instead of regex. — Andrew Marshall
– Andrew Marshall, Commented Sep 13, 2012 at 1:30

Justin Ko · Accepted Answer · 2012-09-13 03:22:10Z

1

You can use the regex:

/<f:HexDump>.*?<\/f:HexDump>/

The key here is making the part between the HexDump tags non-greedy by using the ?.

Assuming your string is stored in str, you can get rid of all the HexDump tags doing:

str.gsub(/<f:HexDump>.*?<\/f:HexDump>/, '')

Note that you might want to enable multi-line mode for the regex (adding m to the end) if there can be return carriages between the tags.

answered Sep 13, 2012 at 3:22

Justin Ko

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