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. liquidsoap-core >= "2.3.0"
  114. liquidsoap-lang >= "2.3.0"
  115. MlFront_Cli >= "2.1.4~prerel2"
  116. magic-trace
  117. mbr-format < "1.0.0"
  118. mdx
  119. mehari
  120. message-switch
  121. mirage >= "0.10.0" & < "2.4.0"
  122. mirage-bootvar-xen < "0.3.2"
  123. mirage-www < "1.0.0"
  124. mparser-re
  125. mustache < "2.0.0"
  126. naboris
  127. netsnmp
  128. ninja_utils
  129. obelisk >= "0.5.0"
  130. ocaml-lsp-server >= "1.7.0"
  131. ocamlformat >= "0.11.0"
  132. ocamlformat-mlx
  133. ocamlformat-rpc < "0.21.0"
  134. ocp-build >= "1.99.21"
  135. ocp-index >= "1.0.2"
  136. ocsigen-start >= "1.7.0"
  137. ocsigenserver >= "5.1.0"
  138. octez-bls12-381-signature
  139. octez-libs
  140. odoc >= "2.0.0" & < "2.1.0"
  141. opam-bin >= "0.9.5" & < "1.1.0"
  142. opam-build-revdeps
  143. opam-client >= "2.0.0~rc2"
  144. opam-compiler
  145. opam-core
  146. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  147. opam-lib
  148. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  149. opam-state >= "2.2.0~alpha"
  150. opam2web >= "1.3.0"
  151. opam_bin_lib
  152. operf-macro
  153. opium >= "0.13.1"
  154. opium_kernel
  155. oranger
  156. orun
  157. ostap
  158. ozulip
  159. pa_ppx_parsetree
  160. pa_ppx_regexp >= "0.03"
  161. pa_ppx_string
  162. patdiff >= "v0.12.0"
  163. pgocaml >= "2.3"
  164. pgx
  165. plato
  166. podge >= "0.3"
  167. ppx_css < "v0.17.0"
  168. ppx_cstubs
  169. ppx_expect >= "113.33.00" & < "v0.17.0"
  170. ppx_implicits >= "0.1.0"
  171. ppx_minidebug >= "1.0.0"
  172. ppx_orakuda >= "3.0.0"
  173. ppx_regexp >= "0.3.2"
  174. ppx_sqlexpr
  175. ppx_test >= "1.1.0"
  176. ppx_tyre
  177. ppxlib >= "0.21.0"
  178. prometheus >= "0.2"
  179. prometheus-app >= "0.2"
  180. pyml_bindgen >= "0.3.1"
  181. rdf >= "0.12.0"
  182. re_parser
  183. reason < "1.7.4"
  184. receive-mail
  185. redis >= "0.2.1"
  186. regenerate
  187. rfc1951 < "1.0.0"
  188. sarek >= "20210823"
  189. sarif >= "0.2.1"
  190. satyrographos >= "0.0.2.7"
  191. semantic_version
  192. sexp_pretty
  193. sill >= "1.3.1"
  194. simple-diff
  195. slug
  196. soupault
  197. spoc >= "20210823"
  198. sqlexpr >= "0.7.1" & < "0.9.0"
  199. swagger
  200. tar < "2.2.0"
  201. tar-format >= "0.2.0"
  202. tar-mirage < "2.2.0"
  203. tar-unix < "2.2.0"
  204. testo
  205. testo-lwt
  206. testo-util
  207. testrunner
  208. tezos-base < "7.4"
  209. tezos-clic < "8.0" | >= "13.0"
  210. tezos-protocol-compiler = "10.2" | = "13.0"
  211. tezos-stdlib-unix >= "7.4"
  212. tezt
  213. timere-parse
  214. touist >= "3.5.0"
  215. tyre >= "0.4"
  216. tyxml >= "4.0.0"
  217. tyxml-syntax
  218. uri < "4.0.0"
  219. uri-re
  220. user-agent-parser
  221. user-setup
  222. uuuu
  223. validate
  224. vendredi
  225. vhd-tool >= "0.12.0"
  226. webmachine
  227. xapi-idl
  228. xe
  229. xen-api-client >= "0.9.6"
  230. 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