Question

I have a custom transport format that packages data up in the following format

[a:000,”name”,”field”,”field”,”field”]

I’m trying to split the individual lines out to get the first character after the left bracket and all the CSV values.
a, 000, “name”, “field”, “field” etc…

I cobbled together

[^?,:\[\]]

This splits all the individual characters out not the colon/comma delimited fields.
I understand this won’t accommodate commas within quotes.So it’s clearly rubbish!

Embedded commas isn’t really a huge issue as we’re in control of the data at both ends so I could just escape them.

Thanks for any insight!

Answer 1

Instead of trying to split on multiple characters and ignore some of them, try to match whatever you want to match. Since you didn’t specify the implementation language I am posting this for Perl but you could apply it to any flavor which supports lookbehind and lookaheads.

while ($subject =~ m/(\w+(?=:)|(?<=:)\d+|(?<=,")[^"]*?(?="))/g) {
    # matched text = $&
}

Explanation:

# (\w+(?=:)|(?<=:)\d+|(?<=,")[^"]*?(?="))
# 
# Match the regular expression below and capture its match into backreference number 1 «(\w+(?=:)|(?<=:)\d+|(?<=,")[^"]*?(?="))»
# Match either the regular expression below (attempting the next alternative only if this one fails) «\w+(?=:)»
# Match a single character that is a “word character” (letters, digits, and underscores) «\w+»
# Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
# Assert that the regex below can be matched, starting at this position (positive lookahead) «(?=:)»
# Match the character “:” literally «:»
# Or match regular expression number 2 below (attempting the next alternative only if this one fails) «(?<=:)\d+»
# Assert that the regex below can be matched, with the match ending at this position (positive lookbehind) «(?<=:)»
# Match the character “:” literally «:»
# Match a single digit 0..9 «\d+»
# Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
# Or match regular expression number 3 below (the entire group fails if this one fails to match) «(?<=,")[^"]*?(?=")»
# Assert that the regex below can be matched, with the match ending at this position (positive lookbehind) «(?<=,")»
# Match the characters “,"” literally «,"»
# Match any character that is NOT a “"” «[^"]*?»
# Between zero and unlimited times, as few times as possible, expanding as needed (lazy) «*?»
# Assert that the regex below can be matched, starting at this position (positive lookahead) «(?=")»
# Match the character “"” literally «"»

See it working.