package re

  1. Overview
  2. Docs
RE is a regular expression library for OCaml

Install

Dune Dependency

github.com Readme Changelog LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception License Edit opam file Versions (23)

Authors

  1. J
    Jerome Vouillon
  2. T
    Thomas Gazagnaire
  3. A
    Anil Madhavapeddy
  4. R
    Rudi Grinberg
  5. Gabriel Radanne

Maintainers

  1. R
    rudi.grinberg@gmail.com

Sources

re-1.12.0.tbz
sha256=a01f2bf22f72c2f4ababd8d3e7635e35c1bf6bc5a41ad6d5a007454ddabad1d4
sha512=f0726826e1e677f7ecdf447d46d814a11d3844ec6e5c0527be8c73c7afdb08aacfca47ea764eda325bcd7064aff07c1d3441c935ee5a0fc99ede8707f81a451d

Description

Pure OCaml regular expressions with:

  • Perl-style regular expressions (module Re.Perl)
  • Posix extended regular expressions (module Re.Posix)
  • Emacs-style regular expressions (module Re.Emacs)
  • Shell-style file globbing (module Re.Glob)
  • Compatibility layer for OCaml's built-in Str module (module Re.Str)

Published: 03 Sep 2024

README

Description

Re is a regular expression library for OCaml.

Contact

This library has been written by Jerome Vouillon (Jerome.Vouillon@pps.univ-paris-diderot.fr). It can be downloaded from https://github.com/ocaml/ocaml-re

Bug reports, suggestions and contributions are welcome.

Features

The following styles of regular expressions are supported:

  • Perl-style regular expressions (module Re.Perl);

  • Posix extended regular expressions (module Re.Posix);

  • Emacs-style regular expressions (module Re.Emacs);

  • Shell-style file globbing (module Re.Glob).

It is also possible to build regular expressions by combining simpler regular expressions (module Re).

The most notable missing features are back-references and look-ahead/look-behind assertions.

There is also a subset of the PCRE interface available in the Re.Pcre module. This makes it easier to port code from that library to Re with minimal changes.

Performances

The matches are performed by lazily building a DFA (deterministic finite automaton) from the regular expression. As a consequence, matching takes linear time in the length of the matched string.

The compilation of patterns is slower than with libraries using back-tracking, such as PCRE. But, once a large enough part of the DFA is built, matching is extremely fast.

Of course, for some combinations of regular expression and string, the part of the DFA that needs to be build is so large that this point is never reached, and matching will be slow. This is not expected to happen often in practice, and actually a lot of expressions that behaves badly with a backtracking implementation are very efficient with this implementation.

The library is at the moment entirely written in OCaml. As a consequence, regular expression matching is much slower when the library is compiled to bytecode than when it is compiled to native code.

Here are some timing results (Pentium III 500Mhz):

  • Scanning a 1Mb string containing only as, except for the last character which is a b, searching for the pattern aa?b (repeated 100 times):

    • RE: 2.6s

    • PCRE: 68s

  • Regular expression example from http://www.bagley.org/~doug/shootout/ [1]

    • RE: 0.43s

    • PCRE: 3.68s

    [1] this page is no longer up but is available via the Internet Archive http://web.archive.org/web/20010429190941/http://www.bagley.org/~doug/shootout/bench/regexmatch/

  • The large regular expression (about 2000 characters long) that Unison uses with my preference file to decide whether a file should be ignored or not. This expression is matched against a filename about 20000 times.

    • RE: 0.31s

    • PCRE: 3.7s However, RE is only faster than PCRE when there are more than about 300 filenames.

Dependencies (3)

  1. seq
  2. dune >= "2.0"
  3. ocaml >= "4.12"

Dev Dependencies (1)

  1. ounit2 with-test

  1. alcotest < "0.4.3" | >= "1.0.0"
  2. alcotest-async >= "1.3.0"
  3. alcotest-lwt >= "1.3.0"
  4. alcotest-mirage >= "1.3.0"
  5. atd >= "2.2.1"
  6. atdd
  7. atdgen >= "2.3.3"
  8. atdgen-runtime = "2.2.1"
  9. atdj >= "2.2.1" & < "20151001.01"
  10. atdpy >= "2.4.1"
  11. atds < "2.3.3"
  12. atdts
  13. aws-config
  14. awsm-codegen
  15. BetterErrors
  16. bap < "1.0.0"
  17. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump < "1.4.0" | >= "1.6.0"
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. bap-server
  25. benchpress
  26. bio_io >= "0.5.1"
  27. biocaml = "0.4.0" | >= "0.8.0"
  28. bistro = "0.5.0"
  29. bonsai >= "v0.15.0"
  30. bulletml
  31. calculon >= "0.2"
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. camlp5 >= "8.00.05"
  36. camlp5-buildscripts
  37. camyll
  38. caqti >= "1.7.0"
  39. catala
  40. ccss >= "1.6"
  41. chamo >= "4.0"
  42. cinaps >= "v0.10.0"
  43. cohttp
  44. coin
  45. colibri2
  46. commons
  47. core_bench >= "v0.9.0"
  48. core_extended >= "v0.10.0"
  49. cosovo
  50. cow < "1.2.2"
  51. cowabloga >= "0.4.0"
  52. cucumber
  53. cuid
  54. current
  55. current_web >= "0.4"
  56. daypack-lib
  57. debian-formats
  58. decompress >= "0.8" & < "1.0.0"
  59. dkml-install-installer >= "0.4.0"
  60. dns < "4.0.0"
  61. dog < "0.2.1"
  62. doi2bib >= "0.5.1"
  63. dose
  64. dose3
  65. dune-release >= "0.2.0"
  66. duppy >= "0.9.4"
  67. elpi
  68. expect_test_helpers_core
  69. expect_test_helpers_kernel
  70. ez_file
  71. ez_search
  72. fat-filesystem != "0.12.0"
  73. frag
  74. gensqlite
  75. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  76. git-split < "1.0.0"
  77. git_split
  78. gpiod
  79. graphql_parser >= "0.11.0"
  80. hardcaml_verify
  81. hardcaml_waveterm
  82. hardcaml_xilinx_components
  83. hlarp >= "0.0.3"
  84. horned_worm
  85. http_router
  86. humane-re
  87. icalendar
  88. imaplet-lwt >= "0.1.9"
  89. index
  90. index-bench
  91. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  92. irmin-bench >= "2.4.0"
  93. iso-filesystem
  94. jingoo >= "1.2.21"
  95. js_of_ocaml >= "3.10.0"
  96. js_of_ocaml-compiler >= "3.10.0"
  97. js_of_ocaml-lwt >= "3.10.0"
  98. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  99. js_of_ocaml-ppx >= "3.10.0"
  100. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  101. js_of_ocaml-toplevel >= "3.10.0"
  102. js_of_ocaml-tyxml >= "3.10.0"
  103. jwt
  104. jwto
  105. kappa-library
  106. kubecaml
  107. labrys
  108. lastfm >= "0.3.4"
  109. ldap >= "2.5.1"
  110. learn-ocaml >= "0.13.0"
  111. libres3 >= "0.3"
  112. lipsum
  113. MlFront_Cli >= "2.1.4~prerel2"
  114. magic-trace
  115. mbr-format < "1.0.0"
  116. mdx
  117. mehari
  118. message-switch
  119. mirage >= "0.10.0" & < "2.4.0"
  120. mirage-bootvar-xen < "0.3.2"
  121. mirage-www < "1.0.0"
  122. mparser-re
  123. mustache < "2.0.0"
  124. naboris
  125. netsnmp
  126. ninja_utils
  127. obelisk >= "0.5.0"
  128. ocaml-lsp-server >= "1.7.0"
  129. ocamlformat >= "0.11.0"
  130. ocamlformat-mlx
  131. ocamlformat-rpc < "0.21.0"
  132. ocp-build >= "1.99.21"
  133. ocp-index >= "1.0.2"
  134. ocsigen-start >= "1.7.0"
  135. ocsigenserver >= "5.1.0"
  136. octez-bls12-381-signature
  137. octez-libs
  138. odoc >= "2.0.0" & < "2.1.0"
  139. opam-bin >= "0.9.5" & < "1.1.0"
  140. opam-build-revdeps
  141. opam-client >= "2.0.0~rc2"
  142. opam-compiler
  143. opam-core
  144. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  145. opam-lib
  146. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  147. opam-state >= "2.2.0~alpha"
  148. opam2web >= "1.3.0"
  149. opam_bin_lib
  150. operf-macro
  151. opium >= "0.13.1"
  152. opium_kernel
  153. oranger
  154. orun
  155. ostap
  156. ozulip
  157. pa_ppx_parsetree
  158. pa_ppx_regexp >= "0.02"
  159. pa_ppx_string
  160. patdiff >= "v0.12.0"
  161. pgocaml >= "2.3"
  162. pgx
  163. plato
  164. podge >= "0.3"
  165. ppx_css < "v0.17.0"
  166. ppx_cstubs
  167. ppx_expect >= "113.33.00" & < "v0.17.0"
  168. ppx_implicits >= "0.1.0"
  169. ppx_minidebug >= "1.0.0"
  170. ppx_orakuda >= "3.0.0"
  171. ppx_regexp >= "0.3.2"
  172. ppx_sqlexpr
  173. ppx_test >= "1.1.0"
  174. ppx_tyre
  175. ppxlib >= "0.21.0"
  176. prometheus >= "0.2"
  177. prometheus-app >= "0.2"
  178. pyml_bindgen >= "0.3.1"
  179. rdf >= "0.12.0"
  180. re_parser
  181. reason < "1.7.4"
  182. receive-mail
  183. redis >= "0.2.1"
  184. regenerate
  185. rfc1951 < "1.0.0"
  186. sarek >= "20210823"
  187. sarif >= "0.2.1"
  188. satyrographos >= "0.0.2.7"
  189. semantic_version
  190. sexp_pretty
  191. sill >= "1.3.1"
  192. simple-diff
  193. slug
  194. soupault
  195. spoc >= "20210823"
  196. sqlexpr >= "0.7.1" & < "0.9.0"
  197. swagger
  198. tar < "2.2.0"
  199. tar-format >= "0.2.0"
  200. tar-mirage < "2.2.0"
  201. tar-unix < "2.2.0"
  202. testo
  203. testo-lwt
  204. testo-util
  205. testrunner
  206. tezos-base < "7.4"
  207. tezos-clic < "8.0" | >= "13.0"
  208. tezos-protocol-compiler = "10.2" | = "13.0"
  209. tezos-stdlib-unix >= "7.4"
  210. tezt
  211. timere-parse
  212. touist >= "3.5.0"
  213. tyre >= "0.4"
  214. tyxml >= "4.0.0"
  215. tyxml-syntax
  216. uri < "4.0.0"
  217. uri-re
  218. user-agent-parser
  219. user-setup
  220. uuuu
  221. validate
  222. vendredi
  223. vhd-tool >= "0.12.0"
  224. webmachine
  225. xapi-idl
  226. xe
  227. xen-api-client >= "0.9.6"
  228. xtmpl >= "0.15.0"

Conflicts

None

OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct