CODEWITHSUNDEEP
iosobjective-cregexswiftstring
adev
adev

Reputation: 2092

Regex to get all substrings before and after given set of words

I am trying to learn Regex and I have scenario where I thought I can use the same. I have a set of strings in the below format(as shown in the table) from which I need to extract each substring around joining operator "and", "or", "not". For eg:- "some column name1 = some value1" as one such substring from first string.

After that I need to extract left hand side string and right hand side string of operators "like", "=", "<", ">". In the above example it would give "some column name1" as one substring and "some value1" as another substring along with operator as "=".

  • some column name1 = some value1 and some column name2 < another value2 or some column name 3 > value3 not column name 4 = value4 and name5 = value5
  • columnA = 324324
  • columnB like a text
  • value text

Since I am new to Regex, this is what I have tried till now but it doesn't seem to give me all the values around these operators. Once this works, I am thinking I can apply similar regex with operators as "like", "=", "<", ">" on the resulting substrings to get final output. 

(.*?)\b(and|or|not)

When I try the above regex on the first example, this part "name5 = value5" is missing after matching.

(.+?)(and|or|not)(.+)

When I try this one, it matches the first substring but rest of them are matched as a single substring instead of splitting those again.

Please note that I was able to use split operation and give "and|or|not" as separator to get array of substrings however I am trying to see if I can directly get these matched substrings from the given string just for learning regex(This answer says it is possible to do using Regex). I have explored stackoverflow for similar questions but none of the solutions worked in my case. The language in my case is Objective C/Swift.

Upvotes: 1

Views: 1257

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626738

You may add an end of string anchor $ as an alternative to the delimiters.

(.*?)(?:\b(and|or|not)\b|$)
                        ^^

See the regex demo.

If your string contains line breaks, you must make . match them by adding (?s), a DOTALL modifier, at the pattern start.

Upvotes: 1

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