Regex pattern for enclosed by string?

Question

I have follwing script and the script outputs a array like below.

[
    [0] "# bash LAN\n\n```\nnmap -sn 192.168.3.*\n```\n",
    [1] "# node.js npm\n\n`sudo apt update && sudo apt install nodejs npm -y`\n",
    [2] "# something title\n\nsomething content\n",
    [3] "# bash log\n\n```\ntail -f",
    [4] "# or",
    [5] "# tail -f -n 50\n```\n\n\n"
]

Encoding.default_external = 'UTF-8'

require 'pry'
require "awesome_print"

# p \
ap \
arrayobj = <<-'EOS'.scan(/^#(?!#).*(?:\R(?!#(?!#)).*)*/) # .scan(/^#.*$\n(.*)/m)


# bash LAN

\```
nmap -sn 192.168.3.*
\```

# node.js npm

`sudo apt update && sudo apt install nodejs npm -y`

# something title

something content

# bash log

\```
tail -f
# or
# tail -f -n 50
\```


EOS

I'd like to split the EOS-enclosed text by #(single hash) but if the single hash is enclosed by Markdown code tag, ignore that single hash.

So, in that case, what I wanted is following output. How do you get the output?

[
    [0] "# bash LAN\n\n```\nnmap -sn 192.168.3.*\n```\n",
    [1] "# node.js npm\n\n`sudo apt update && sudo apt install nodejs npm -y`\n",
    [2] "# something title\n\nsomething content\n",
    [3] "# bash log\n\n```\ntail -f\n# or\n# tail -f -n 50\n```\n\n\n",
]

Perhaps this is helpful? https://stackoverflow.com/a/23589221/5961578 — moveson, Jan 17 '19 at 06:23
Probably best to do it line by line and turn a flag on/off when encountering a ``` tag — Kimmo Lehto, Jan 17 '19 at 07:19

score 0 · Accepted Answer · answered Jan 17 '19 at 08:23

You may use

.scan(/^#(?!#)(?:(?!```)[^#]|```.*?```)*/m).flatten

See the Ruby demo and a Rubular demo.

Details

^ - start of a line
#(?!#) - a # not followed with another #
(?:(?!```)[^#]|```.*?```)* - 0 or more repetitions of
- (?!```)[^#] - any char other than # that does not start a ``` char sequence
- | - or
- ``` - three backticks
- .*? - any 0+ chars, as few as possible
- ``` - three backticks

The m modifier makes . match any char including line break chars.

score 0 · Answer 2 · answered Jan 17 '19 at 15:20

What I would do in this case is maybe not completely standard, but here you are:

Split the string on triple quotes:
```
.split('```')
```
Take the pieces in pairs. First piece is normal markdown, second is code snippet.
```
.each_slice(2)
```
Add markers before # in the first piece, not in the second. Notice that the MD piece is nil in the last slice.
```
.map { |txt, code = nil| [txt.gsub('#', "\x00#"), code].compact }
```
Join back
```
.flatten.join('```')
```
Split by marker
```
.split("\x00")
```

The byte '0' is not expected to be in your text, if you have it, just use another marker, like a long random string without any # that you generate when starting the process.

Regex pattern for enclosed by string?

2 Answers2