Comparison of regular expression engines

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This is a comparison of regular expression engines.

Contents

Libraries

List of regular expression libraries
NameOfficial website Programming language Software license Used by
Boost.Regex [Note 1] Boost C++ Libraries C++ Boost Notepad++ >= 6.0.0, EmEditor
Boost.Xpressive Boost C++ Libraries C++Boost 
DEELX RegExLab C++ Proprietary  
FREJ [Note 2] Fuzzy Regular Expressions for Java Java LGPL  
GLib/GRegex [Note 3] GLib reference manual C LGPL 
GNU regex Gnulib reference manual CLGPL GNU libc, GNU programs
GRETA Microsoft Research C++ Proprietary  
Gregex Grovf Inc. RTL, HLS Proprietary FPGA accelerated >100 Gbit/s regex engine for cybersecurity, financial, e-commerce industries.
Hyperscan Intel C, x86-specific assembly (SSSE3+ [1] )3-clause BSD Rspamd
ICU International Components for Unicode C, C++ [Note 4] ICU Foundation (Apple and Swift open-source versions)
Jakarta Regexp The Apache Jakarta Project Java Apache  
java.util.regex Java's User manual JavaGNU GPLv2 with Classpath exception jEdit
JRegex JRegex JavaBSD 
MATLAB Regular Expressions MATLAB Language Proprietary  
Oniguruma Kosako CBSD Atom, Take Command Console, Tera Term, TextMate, Sublime Text, SubEthaEdit, EmEditor, jq, Ruby
PattwoStevesoftJava (compatible with Java 1.0)LGPL 
PCRE pcre.org C, C++ [Note 5] BSD Apache HTTP Server, Nginx, BBEdit, Edbrowse, Julia, HHVM, Notepad++ < 6.0.0, PHP, Delphi, R, Exim, SWI-Prolog, Elixir, Erlang
Qt/QRegExp Digia Archived 2013-12-12 at the Wayback Machine C++ Qt GNU GPL v. 3.0,

Qt GNU LGPL v. 2.1, Qt Commercial

Kate, Kile
regex - Henry Spencer's regular expression libraries ArgList CBSD 
RE2 RE2 C++BSD Go, Google Sheets, Gmail, G Suite
Henry Spencer's Advanced Regular Expressions Tcl CBSD 
RGX RGX C++ based component library P6R  
RXP Titan IC RTL Proprietary hardware-accelerated search acceleration using RegEx available for ASIC, FPGA and cloud. Enables massively parallel content processing at ultra-high speeds.
SubReg Matt Bucknall CMIT 
TPerlRegEx TPerlRegEx VCL Component Object Pascal MPLv1.1  
TRE [Note 2] Ville Laurikari CBSD musl
TRegExpr TRegExpr, documentation,

(RegExp Studio)

Object PascalDual-license: freeware, or LGPL with static linking exception Total Commander
Wolfram Language (Mathematica) Wolfram Language Documentation Center Wolfram Language Proprietary Mathematica, the Wolfram Development Platform
XRegExp XRegExp JavaScript MIT  
  1. ↑ Formerly called Regex++.
  2. 1 2 One of fuzzy regular expression engines.
  3. ↑ Included since version 2.13.0.
  4. ↑ ICU4J, the Java version, does not support regular expressions.
  5. ↑ C++ bindings were developed by Google and became officially part of PCRE in 2006.

Languages

List of languages and frameworks including regular expression support
LanguageOfficial website Software license Remarks
ActionScript 3 ActionScript Technology Center Free
APL (APLX, Dyalog, GNU) APL Wiki Licensed by the respective implementation⎕SS (PCRE), ⎕R/⎕S (PCRE), ⎕SS (PCRE2), respectively
C++11 (C++) C++ standards website Licensed by the respective implementationSince ISO14822:2011(e), similar to ECMAScript on default (Grammar Description)
D D Boost Software License [Note 1]
Elixir elixir-lang.org Apache 2.0 Standard library includes PCRE-based Regex module. The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and some parts of the library go beyond what PCRE offers. Currently PCRE version 8.40 (release date 2017-01-11) is used.
Erlang erlang.org Apache 2.0 Standard library includes PCRE-based re module. The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and some parts of the library go beyond what PCRE offers. Currently PCRE version 8.40 (release date 2017-01-11) is used.
Free Pascal (Object Pascal) freepascal.org LGPL with static linking exceptionFree Pascal 2.6+ ships with TRegExpr from Sorokin and two other regular expression libraries; See wiki.lazarus.freepascal.org/Regexpr.
Go go.dev BSD-style
Haskell Haskell.org BSD3 Omitted in the language report, and in GHC's Hierarchical Libraries
Java Java GNU General Public License REs are written as strings in source code: all backslashes must be doubled, harming readability.
JavaScript (ECMAScript) ECMA-262 BSD3 Limited but REs are first-class citizens of the language with a specific /.../mod syntax.
Julia JuliaLang.org MIT License REs are part of the language core library using PCRE built-in and an optional wrapper for (C code) ICU is available.
Lua Lua.org MIT License Uses simplified, limited dialect; can be bound to more powerful library, like PCRE or an alternative parser like LPeg.
Mathematica Wolfram Proprietary
.NET MSDN MIT License [Note 2] [Note 3]
Nim nim-lang.org MIT License Standard library includes PCRE-based re and nre modules, as well as various alternatives (ex. strutils, pegs (Parsing Expression Grammar matching), strscans, parseutils, etc.).
OCaml Caml LGPL As of 2010, the standard module is generally regarded as deprecated; [2] often recommended libraries are pcre (with full support for PCRE) and re (which is not as complete but claims better performance and provides frontends to popular syntaxes: PCRE, Perl, Posix, Emacs, shell globbing).
Perl Perl.com Artistic License, or GNU General Public License Full, central part of the language
PHP PHP.net PHP License Has two implementations, with PCRE being the more efficient in speed, functions
POSIX C (C) POSIX.1 web publication Licensed by the respective implementationSupports POSIX BRE and ERE syntax
Python python.org Python Software Foundation License Python has two major implementations, the built in re and the regex library.
Ruby ruby-doc.org GNU Library General Public License Ruby 1.8, Ruby 1.9, and Ruby 2.0 and later versions use different engines; Ruby 1.9 integrates Oniguruma, Ruby 2.0 and later integrate Onigmo, a fork from Oniguruma.
Rust docs.rs MIT License The primary regex crate does not allow look-around expressions. There is an Oniguruma binding called onig that does.
SAP ABAP SAP.com Proprietary
Tcl tcl.tk Tcl/Tk License
(BSD-style)		Tcl library doubles as a regular expression library.
Wolfram Language Wolfram Research Proprietary: usable for free on a limited scale on the Wolfram Development platform
XML Schema W3C Licensed by the respective implementation
XPath 3/XQuery W3C Licensed by the respective implementation
  1. ↑ "STD.regex - D Programming Language - Digital Mars".
  2. ↑ "Dotnet/Corefx". GitHub . 16 February 2022.
  3. ↑ "Dotnet/Corefx". GitHub . 16 February 2022.

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

Language feature comparison (part 1)
"+" quantifierNegated character classesNon-greedy quantifiers
[Note 1] 		Shy groups
[Note 2] 		RecursionLook-aheadLook-behindBackreferences
[Note 3] 		>9 indexable captures
Boost.Regex YesYesYesYesYes [Note 4] YesYesYesYes
Boost.Xpressive YesYesYesYesYes [Note 5] YesYesYesYes
CL-PPCRE YesYesYesYesNoYesYesYesYes
EmEditor YesYesYesYesNoYesYesYesNo
FREJ No [Note 6] NoSome [Note 6] YesNoNoNoYesYes
GLib/GRegexYesYesYesYesYesYesYesYesYes
GNU grep YesYesYesYesNoYesYesYes—
Haskell YesYesYesYesNoYesYesYesYes
RXP YesYesYesYesNoNoNoYesYes
ICU RegexYesYesYesYesNoYesYesYesYes
Java YesYesYesYesNoYesYesYesYes
JavaScript (ECMAScript)YesYesYesYesNoYesYes [Note 7] YesYes
JGsoft YesYesYesYesYes [3] YesYesYesYes
Lua YesYesSome [Note 8] NoNoNoNoYesNo
.NET YesYesYesYesNoYesYesYesYes
OCaml YesYesNoNoNoNoNoYesNo
PCRE YesYesYesYesYesYesYesYesYes
Perl YesYesYesYesYesYesYesYesYes
PHP YesYesYesYesYesYesYesYesYes
Python YesYesYesYesYes [Note 9] YesYesYesYes
Qt/QRegExpYesYesYesYesNoYesNoYesYes
RE2 YesYesYesYesNoNoNoNoYes
Ruby, Onigmo YesYesYesYesYesYesYesYesYes
TRE YesYesYesYesNoNoNoYesNo
Vim YesYesYesYesNoYesYesYesNo
RGXYesYesYesYesNoYesYesYesYes
Tcl YesYesYesYesNoYesYesYesYes
TRegExprYes ?Yes ? ? ? ? ? ?
XML Schema YesYesNo—NoNoNoNo—
XPath 3/XQuery YesYesYesYesNoNoNoYesYes
XRegExp YesYesYesYesNoYesYes [Note 7] YesYes
  1. ↑ 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.
  2. ↑ 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.
  3. ↑ 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".
  4. ↑ "Perl Regular Expression Syntax - 1.47.0".
  5. ↑ "User's Guide - 1.47.0".
  6. 1 2 FREJ have no repetitive quantifiers, but have "optional" element which behaves similar to simple "?" quantifier.
  7. 1 2 As of ES2018
  8. ↑ 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.
  9. ↑ Supported by the optional regex library only.

Part 2

Language feature comparison (part 2)
Directives
[Note 1] 		ConditionalsAtomic groups
[Note 2] 		Named capture
[Note 3] 		CommentsEmbedded code Unicode property support [4] Balancing groups
[Note 4] 		Variable-length look-behinds
[Note 5]
Boost.Regex YesYesYesYesYesNoSome [Note 6] NoNo
Boost.Xpressive YesNoYesYesYesNoNoNoNo
CL-PPCRE YesYesYesYesYesYesSome [Note 6] NoNo
EmEditor YesYes ? ?YesNo ?NoNo
FREJ NoNoYesYesYesNo ?NoNo
GLib/GRegexYesYesYesYesYesNoSome [Note 6] NoNo
GNU grep YesYes ?YesYesNoNoNoNo
Haskell  ? ? ? ? ?NoNoNoNo
RXP YesYesNoYesYesNoNoNoNo
ICU RegexYesNoYesYes [Note 7] YesNoYesNoNo
Java YesNoYesYes [Note 8] YesNoSome [Note 6] NoNo
JavaScript (ECMAScript)NoNoNoYesNoNoSome [Note 6] [Note 9] [5] NoYes
JGsoft YesYesYesYesYesNoSome [Note 6] NoYes
Lua NoNoNoNoNoNoNoNoNo
.NET YesYesYesYesYesNoSome [Note 6] YesYes
OCaml NoNoNoNoNoNoNoNoNo
PCRE YesYesYesYesYesYesYesNoNo
Perl YesYesYesYesYesYesYesNoNo [Note 10]
PHP YesYesYesYesYesNoNoNoNo
Python YesYesYes [Note 11] YesYesNoYes [Note 12] NoYes [Note 13]
Qt/QRegExpNoNoNoNoNoNoNoNoNo
RE2 YesNo ?YesNoNoSome [Note 6] NoNo
Ruby, Onigmo YesYesYesYesYesNoSome [Note 6] NoNo
Tcl YesNoYesNoYesNoYesNoNo
TRE YesNoNoNoYesNo ?NoNo
Vim YesNoYesNoNoNoNoNoYes
RGXYesYesYesYesYesNoYesNoNo
XML Schema NoNoNoNoNoNoYesNoNo
XPath 3/XQuery NoNoNoNoNoNoYesNoNo
XRegExp Leading onlyNoNoYesYesNoYesNoYes
  1. ↑ Also known as flags modifiers, modes modifiers or option letters. Example pattern: "(?i:test)".
  2. ↑ Also called independent sub-expressions.
  3. ↑ Similar to back references, but with names instead of indices.
  4. ↑ Special feature allowing to match balanced constructs without recursion.
  5. ↑ Refers to the possibility of including quantifiers in look-behinds, thus making their length unpredictable.
  6. 1 2 3 4 5 6 7 8 9 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.
  7. ↑ Available as of ICU55.
  8. ↑ Available as of JDK7.
  9. ↑ The support and range of properties is dependent on implementation.
  10. ↑ Experimental support added in v5.29.9.
  11. ↑ Supported by Python v3.11 and later, and the optional regex library only.
  12. ↑ May only be available in the regex library when used with Python versions after 3.3.
  13. ↑ Supported by the optional regex library only.

API features

API feature comparison
Native UTF-16 support [Note 1] Native UTF-8 support [Note 1] Multi-line matchingPartial match [Note 2]
Boost.Regex NoNoYesYes
GLib/GRegexYesYesYesYes
RXP YesYesNoYes
ICU RegexYesNoYes ?
Java Yes [Note 3] Yes [Note 3] YesYes
.NET No [Note 4] YesYes ?
PCRE Yes [Note 5] YesYesYes
Qt/QRegExpYesNoNoYes [Note 6]
Qt/QRegularExpressionYesYesYesYes
Tcl YesYes [Note 7] Yes ?
TRE YesYesYes ?
RGXNoNoYes ?
wxWidgets::wxRegEx [Note 8] YesYesYes ?
XRegExp YesYesYesNo
  1. 1 2 Means the format can be used internally without explicit conversion.
  2. ↑ Partial match of the whole regular expression. For example the pattern ".*END$" will match any string partially, but only strings ending with END fully..
  3. 1 2 Supports Unicode 15.0 standard from 2023..
  4. ↑ 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..
  5. ↑ Since version 8.30.
  6. ↑ Partial matching is performed implicitly, requiring a separate call to matchedLength() if an exact match fails.
  7. ↑ Tcl includes facilities to convert to and from UTF-8.
  8. ↑ wxRegEx uses any system supplied POSIX library or if not available and for Unicode mode uses Henry Spencer's library.

See also

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References

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