I tried writing three regular expressions in a the most common JVM languages.
- Find first match
- Find all matches
- Replace first match
My experience in these languages range from use it many times a week (Groovy) to this is the first thing I’ve written in it (Clojure).
I’m going to be using these in a presentation. So if you see anything in here that is a bad idiom in the language, do let me know!
Kotlin
The WordPress syntax highlighter doesn’t have Kotlin as a choice
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | val text = "Mary had a little lamb"val regex = Regex("\\b\\w{3,4} ")print(regex.find(text)?.value)-----------------------------------------val text = "Mary had a little lamb"val regex = "\\b\\w{3,4} ".toRegex()regex.findAll(text) .map { it.groupValues[0] } .forEach { print(it) }-----------------------------------------val text = "Mary had a little lamb."val wordBoundary = "\\b"val threeOrFourChars = "\\w{3,4}"val space = " "val regex = Regex(wordBoundary + threeOrFourChars + space) println(regex.replaceFirst(text, "_")) |
Scala
Thanks to dhinojosa for the code review and feedback that smart quotes don’t require backslashes inside!
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | val text = "Mary had a little lamb"val regex = """\b\w{3,4} """.rval optional = regex findFirstIn text println(optional.getOrElse("No Match"))-----------------------------------------val text = "Mary had a little lamb."val regex = """\b\w{3,4} """.rval it = regex findAllIn text it foreach print-----------------------------------------val text = "Mary had a little lamb."val wordBoundary = """\b"""val threeOrFourChars = """\w{3,4}"""val space = " "val regex = new Regex(wordBoundary + threeOrFourChars + space) println(regex replaceFirstIn(text, "_")) |
Closure
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | (println( re-find #”\b\w{3,4} ", "Mary had a little lamb"))-----------------------------------------(println( re-seq #”\b\w{3,4} ", "Mary had a little lamb"))-----------------------------------------(ns clojure.examples.example (:gen-class))(defn Replacer [] (def text "Mary had a little lamb.") (def wordBoundary "\\b") (def threeOrFourChars "\\w{3,4}") (def space " ") (def regex (str wordBoundary threeOrFourChars space)) (def pat (re-pattern regex)) (println(clojure.string/replace-first text pat "_")))(Replacer) |
Groovy
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | def text = 'Mary had a little lamb'def regex = /\b\w{3,4} /def matcher = text =~ regexprint matcher[0]-----------------------------------------def text = 'Mary had a little lamb'def regex = /\b\w{3,4} /def matcher = text =~ regexprint matcher.findAll().join(' ')-----------------------------------------def text = 'Mary had a little lamb'def regex = /\b\w{3,4} /def matcher = text =~ regexprint matcher.findAll().join(' ') |
