I have a serialized object that looks like this (not including inverted commas):
'key1:value1,key2:value2,key3:value3'
It could also look like this:
'key1:value1,key3:value3'
OR
'key1:value1'
OR
'' (it could be empty)
At this point i have this token-izing logic break up this string (which is a tad bit verbose). Is there a single regular expression that can help me extract values for a given key (or return null) given any of the above strings?
Keyword matching is straight-forward if you know exact boundaries. In this case, you have single apostrophes as string boundaries and a comma as a separator. So, this is the regex to match a value for a given key (based on your input example):
(?<=key1\:).+?(?=,|'|$) --> finds 3 "value1" matches
(?<=key2\:).+?(?=,|'|$) --> finds 1 "value2" match
(?<=key3\:).+?(?=,|'|$) --> finds 2 "value3" matches
(?<=key4\:).+?(?=,|'|$) --> no match
I guess all you need is to find key/value pairs:
The simplest regex you can use is:
([^:,]+):([^:,]+)
Demo.
This will match a key in $1 and a value in $2. Simple enough.
Now you could introduce variations if you want to:
(\w+):(.+?)(?=,|$)
Demo.
This one ensures the key only contains alphanumeric characters and underscores, and makes sure the value either ends with a comma or at the end of the string. Hopefully you get the point.
Regular expression engines vary a lot by language, and since you didn't tag your question with one, I'm giving you a simple Ruby solution. The following will split your string on either a colon or a comma:
'key1:value1,key2:value2,key3:value3'.split /:|,/
#=> ["key1", "value1", "key2", "value2", "key3", "value3"]
value? If text strings, for example, any straightforward solution depending on:and,need to be not-so-straightforward after all. – Jongware