Libraries

Languages

Language features

NOTE: An application using a library for regular expression support does not necessarily support the full set of features of the library, e.g., GNU grep uses PCRE, but supports no lookahead, though PCRE does.

Part 1

Part 2

API features

See also

• Regular expression § Implementations and running times
• Comparison of parser generators

External links

• Regular Expression Flavor Comparison – Detailed comparison of the most popular regular expression flavors
• Regexp Syntax Summary
• Online Regular Expression Testing – with support for Java, JavaScript, .Net, PHP, Python and Ruby
• Implementing Regular Expressions – series of articles by Russ Cox, author of RE2
• Regular Expression Engines

References

1. Formerly called Regex++. ↩

2. One of fuzzy regular expression engines. /wiki/Regular_expression#Fuzzy_regular_expressions ↩

3. Included since version 2.13.0. ↩

4. "Getting Started – Hyperscan 5.4.0 documentation". https://intel.github.io/hyperscan/dev-reference/getting_started.html#requirements ↩

5. ICU4J, the Java version, does not support regular expressions. ↩

6. C++ bindings were developed by Google and became officially part of PCRE in 2006. ↩

7. One of fuzzy regular expression engines. /wiki/Regular_expression#Fuzzy_regular_expressions ↩

8. "STD.regex - D Programming Language - Digital Mars". http://www.digitalmars.com/d/2.0/phobos/std_regex.html ↩

9. "Dotnet/Corefx". GitHub. 16 February 2022. https://github.com/dotnet/corefx/blob/7116584186f8f3a886616aaf8cb5d4a982c60e27/src/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.cs#L2 ↩

10. "Dotnet/Corefx". GitHub. 16 February 2022. https://github.com/dotnet/corefx#license ↩

11. "Regex - Regular Expressions in OCaml". https://stackoverflow.com/questions/3221067#comment3323649_3221067 ↩

12. Non-greedy quantifiers match as few characters as possible, instead of the default as many. Note that many older, pre-POSIX engines were non-greedy and didn't have greedy quantifiers at all. /wiki/POSIX ↩

13. Shy groups, also called non-capturing groups cannot be referred to with backreferences; non-capturing groups are used to speed up matching where the group's content does not need to be accessed later. ↩

14. Backreferences enable referring to previously matched groups in later parts of the regex and/or replacement string (where applicable). For instance, ([ab]+)\1 matches "abab" but not "abaab". ↩

15. "Perl Regular Expression Syntax - 1.47.0". http://www.boost.org/doc/libs/1_47_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html#boost_regex.syntax.perl_syntax.recursive_expressions ↩

16. "User's Guide - 1.47.0". http://www.boost.org/doc/libs/1_47_0/doc/html/xpressive/user_s_guide.html#boost_xpressive.user_s_guide.grammars_and_nested_matches.embedding_a_regex_by_reference ↩

17. FREJ have no repetitive quantifiers, but have "optional" element which behaves similar to simple "?" quantifier. ↩

18. FREJ have no repetitive quantifiers, but have "optional" element which behaves similar to simple "?" quantifier. ↩

19. As of ES2018 ↩

20. "Recursive Regex—Tutorial". https://www.rexegg.com/regex-recursion.php#engines ↩

21. Lua's only non-greedy quantifier is -, which is a non-greedy version of *. It does not have non-greedy versions of + or ?; in the former case, the non-greedy effect can be achieved by repeating the token followed by -, but in the latter case, there is no equivalent. ↩

22. Supported by the optional regex library only. https://pypi.org/project/regex/#recursive-patterns-hg-issue-27 ↩

23. As of ES2018 ↩

24. Also known as flags modifiers, modes modifiers or option letters. Example pattern: "(?i:test)". ↩

25. Also called independent sub-expressions. ↩

26. Similar to back references, but with names instead of indices. ↩

27. "UTS #18: Unicode Regular Expressions". https://www.unicode.org/reports/tr18/ ↩

28. Special feature allowing to match balanced constructs without recursion. ↩

29. Refers to the possibility of including quantifiers in look-behinds, thus making their length unpredictable. ↩

30. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

31. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

32. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

33. Available as of ICU55. ↩

34. Available as of JDK7. ↩

35. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

36. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

37. The support and range of properties is dependent on implementation. ↩

38. "ECMA-262, 9th edition, June 2018 ECMAScript® 2018 Language Specification". www.ecma-international.org. Retrieved 4 August 2020. https://www.ecma-international.org/ecma-262/9.0/#sec-runtime-semantics-unicodematchproperty-p ↩

39. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

40. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

41. Experimental support added in v5.29.9. ↩

42. Supported by Python v3.11 and later, and the optional regex library only. https://pypi.python.org/pypi/regex ↩

43. May only be available in the regex library when used with Python versions after 3.3. ↩

44. Supported by the optional regex library only. https://pypi.python.org/pypi/regex ↩

45. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

46. Unicode property support may be incomplete (products are continuously updated!). All will be incomplete when a new Unicode revision is released until they are updated to comply. ↩

47. Means the format can be used internally without explicit conversion. ↩

48. Means the format can be used internally without explicit conversion. ↩

49. Partial match of the whole regular expression. For example the pattern ".*END$" will match any string partially, but only strings ending with END fully.[1]. http://www.boost.org/doc/libs/1_34_1/libs/regex/doc/partial_matches.html ↩

50. Supports Unicode 15.0 standard from 2023.[2]. https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Character.html ↩

51. Supports Unicode 15.0 standard from 2023.[2]. https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Character.html ↩

52. Implementation uses original UCS-2 support/features, so it only recognizes 64K chars total (vs UTF-16's 1,112,064 characters). A Microsoft developer-representative answered a bug report on this as "will not fix" in 2010.[3]. /wiki/UCS-2 ↩

53. Since version 8.30. ↩

54. Partial matching is performed implicitly, requiring a separate call to matchedLength() if an exact match fails. ↩

55. Tcl includes facilities to convert to and from UTF-8. ↩

56. wxRegEx uses any system supplied POSIX library or if not available and for Unicode mode uses Henry Spencer's library. /wiki/POSIX ↩