Issue: Unnecessary runtime regex compilation in version normalization code #560
Description
In the JetBrains Runtime codebase(not in openJdk), there is a section that repeatedly compiles regular expressions at runtime when normalizing version strings.
This causes unnecessary performance overhead.
Current code example:
String res = Arrays.stream(matcher.group().split("\\."))
.filter(s -> s.matches("\\d+"))
.map(s -> s.replaceFirst("^0*", ""))
.map(s -> s.isEmpty() ? "0" : s)
.collect(Collectors.joining("."));
return !res.isEmpty() ? res : "0";
Suggested improvement
Use precompiled regex patterns for the two expressions that are repeatedly used:
private static final Pattern DIGITS_ONLY = Pattern.compile("\\d+");
private static final Pattern LEADING_ZEROS = Pattern.compile("^0*");
Updated code:
String res = Arrays.stream(matcher.group().split("\\."))
.filter(s -> DIGITS_ONLY.matcher(s).matches())
.map(s -> LEADING_ZEROS.matcher(s).replaceFirst(""))
.map(s -> s.isEmpty() ? "0" : s)
.collect(Collectors.joining("."));
return !res.isEmpty() ? res : "0";