Comparison of regular expression engines

Libraries

List of regular expression libraries

	Official website	Programming language	Software license
Boost.Regex Template:Ref label	Boost C++ Libraries	C++	Boost Software License
Boost.Xpressive	Boost C++ Libraries	C++	Boost Software License
CL-PPCRE	Edi Weitz	Common Lisp	BSD
DEELX	RegExLab	C++	"free for personal use and commercial use"
GLib/GRegex Template:Ref label	Marco Barisione	C	LGPL
GRETA	Microsoft Research	C++	?
ICU	International Components for Unicode	C/C++/Java	ICU license
Jakarta/Regexp	The Apache Jakarta Project	Java	Apache License
JRegex	JRegex	Java	BSD
Oniguruma	Kosako	C	BSD
Pattwo	Stevesoft	Java (compatible with Java 1.0)	LGPL
PCRE	Philip Hazel	C/C++Template:Ref label	BSD
Qt/QRegExp	Qt Software	C++	Qt GNU GPL v. 3.0 / Qt GNU LGPL v. 2.1 / Qt Commercial
regex - Henry Spencer's regular expression libraries	ArgList	C	BSD
TRE	Ville Laurikari	C	BSD
TPerlRegEx	TPerlRegEx VCL Component	Object Pascal	MPLv1.1
TRegExpr	RegExp Studio	Object Pascal	Freeware

Template:Note label formerly called Regex++

Template:Note label included since version 2.13.0

Template:Note label C++ bindings were developed by Google and became officially part of PCRE in 2006

Languages

List of languages coming with regular expression support

Language	Official website	Software license	Remarks
.NET	MSDN	Proprietary
D	D	Proprietary
Haskell	Haskell.org	BSD3
Java	Java	GNU General Public License	REs are written as strings (all backslashes must be doubled, hurting readability).
JavaScript/ECMAScript		?	Limited but REs are first-class citizens of the language with a specific /.../mod syntax.
Lua	Lua.org	MIT License	Uses a simplified, limited dialect. Can be bound to a more powerful library, like PCRE or an alternative parser like LPeg.
Perl	Perl.com	Artistic License or the GNU General Public License	Full, central part of the language.
PHP	PHP.net	?	Has two implementations, PCRE being the most efficient (speed, functionalities).
Python	python.org	Python Software Foundation License
Ruby	ruby-doc.org	GNU Library General Public License
SAP ABAP	SAP.com	?
Tcl 8.4	tcl.tk	Tcl/Tk License (Permissive, similar to BSD)

Language features

NOTE: An application using a library for regular expression support does not necessarily offer the full set of features of the library, e.g. GNU Grep which uses PCRE does not offer lookahead support, though PCRE does.

Part 1

Language feature comparison (part 1)

	"+" quantifier	Negated character classes	Non-greedy quantifiersTemplate:Refun	Shy groupsTemplate:Refun	Lookahead	Lookbehind	BackreferencesTemplate:Refun	>9 indexable captures
Boost.Regex	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Boost.Xpressive	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
CL-PPCRE	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
EmEditor	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No
GLib/GRegex	?	?	?	?	?	?	?	?
GNU Grep	Yes	Yes	Yes	Yes	Yes	Yes	Yes	?
Haskell	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Java	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
ICU Regex	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
JGsoft	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
.NET	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
OmniOutliner 3.6.2	Yes	Yes	Yes	No	No	No	?	?
PCRE	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Perl	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
PHP	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Python	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Qt/QRegExp	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes
Ruby	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes
TRE	Yes	Yes	Yes	Yes	No	No	Yes	No
Vim Template:Latest preview release/Vim	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No

• ^  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
• ^  Shy groups, also called non-capturing groups cannot be referred to with backreferences; non-capturing groups are used to speed up matching where the groups content needs not be accessed later.
• ^  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"

Part 2

Language feature comparison (part 2)

	Directives Template:Refun	Conditionals	Atomic groups Template:Refun	Named capture Template:Refun	Comments	Embedded code	Partial matching	Fuzzy matching	Unicode property support [1]
Boost.Regex	Yes	Yes	Yes	Yes	Yes	No	Yes	No	Yes Template:Refun
Boost.Xpressive	Yes	No	Yes	Yes	Yes	No	Yes	No	No
CL-PPCRE	Yes	Yes	Yes	Yes	Yes	Yes	?	No	No
EmEditor	Yes	Yes	?	?	Yes	No	Yes	No	?
GLib/GRegex	?	?	?	?	?	No	Yes	No	Yes Template:Refun
GNU Grep	Yes	Yes	?	Yes	Yes	No	?	No	No
Haskell	?	?	?	?	?	No	?	No	No
Java	Yes	Yes	Yes	Yes	No	No	?	No	Yes
ICU Regex	Yes	Yes	Yes	No	Yes	No	No	No	Yes
JGsoft	Yes	Yes	Yes	Yes	Yes	No	Yes	?	Yes
.NET	Yes	Yes	Yes	Yes	Yes	No	?	No	Yes
OmniOutliner 3.6.2	?	?	?	?	No	No	?	No	?
PCRE	Yes	Yes	Yes	Yes Template:Refun	Yes	Yes	Yes	No	Yes Template:Refun
Perl	Yes	Yes	Yes	Yes Template:Refun	Yes	Yes	No	No	Yes
PHP	Yes	Yes	Yes	Yes	Yes	No	No	No	No
Python	Yes	Yes	No	Yes	Yes	No	No	No	No
Qt/QRegExp	No	No	No	No	No	No	Yes	No	Yes
RubyTemplate:Refun	Yes	No	No	No	Yes	Yes	No	No	No
TRE	Yes	No	No	No	Yes	No	No	Yes	?
Vim Template:Latest preview release/Vim	Yes	?	Yes	?	?	No	Yes	No	?

• ^  Also known as Flags modifiers or Option letters. Example pattern: "(?i:test)"
• ^  Also called Independent sub-expressions
• ^  Similar to back references but with names instead of indices
• ^  Available as of PCRE 7.0 (as of PCRE 4.0 with Python-like syntax (?P<name>...))
• ^  Available as of perl 5.9.5
• ^  Requires optional Unicode support enabled.
• ^  As of Ruby 1.8. The current development version, Ruby 1.9, has additional features.

API features

API feature comparison

	Native UTF-16 support Template:Refun	Native UTF-8 support Template:Refun	Non-linear input support	Dot-matches-newline option	Anchor-matches-newline option
Boost.Regex	No	No	Yes	Yes	Yes
Boost.Xpressive	?	?	?	?	?
GLib/GRegex	No	Yes Template:Refun	No	Yes	Yes
ICU Regex	Yes	No	No	Yes	?
Java	Yes	?	?	Yes	Yes
.NET	Yes	No	Yes	Yes	?
PCRE	No	Yes Template:Refun	No	Yes	Yes
Qt/QRegExp	Yes	No	No	No	No
TRE	No	?	Yes	Yes	Yes

• ^  Native support means that conversion between UTF-16 <-> UTF-8 isn't required, the Unicode properties are supported, and the encoding type is always available (platform dependent wchar_t doesn't count).

See also

• List of regular expression software

External links

• Regular Expression Flavor Comparison — Detailed comparison of the most popular regular expression flavors
• Regexp Syntax Summary