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-rpc < "0.21.0"
  131. ocp-build >= "1.99.21"
  132. ocp-index >= "1.0.2"
  133. ocsigen-start >= "1.7.0"
  134. ocsigenserver >= "5.1.0"
  135. octez-bls12-381-signature
  136. octez-libs
  137. odoc >= "2.0.0" & < "2.1.0"
  138. opam-bin >= "0.9.5" & < "1.1.0"
  139. opam-build-revdeps
  140. opam-client >= "2.0.0~rc2"
  141. opam-compiler
  142. opam-core
  143. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  144. opam-lib
  145. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  146. opam-state >= "2.2.0~alpha"
  147. opam2web >= "1.3.0"
  148. opam_bin_lib
  149. operf-macro
  150. opium >= "0.13.1"
  151. opium_kernel
  152. oranger
  153. orun
  154. ostap
  155. ozulip
  156. pa_ppx_parsetree
  157. pa_ppx_regexp >= "0.02"
  158. pa_ppx_string
  159. patdiff >= "v0.12.0"
  160. pgocaml >= "2.3"
  161. pgx
  162. plato
  163. podge >= "0.3"
  164. ppx_css < "v0.17.0"
  165. ppx_cstubs
  166. ppx_expect >= "113.33.00" & < "v0.17.0"
  167. ppx_implicits >= "0.1.0"
  168. ppx_minidebug >= "1.0.0"
  169. ppx_orakuda >= "3.0.0"
  170. ppx_regexp >= "0.3.2"
  171. ppx_sqlexpr
  172. ppx_test >= "1.1.0"
  173. ppx_tyre
  174. ppxlib >= "0.21.0"
  175. prometheus >= "0.2"
  176. prometheus-app >= "0.2"
  177. pyml_bindgen >= "0.3.1"
  178. rdf >= "0.12.0"
  179. re_parser
  180. reason < "1.7.4"
  181. receive-mail
  182. redis >= "0.2.1"
  183. regenerate
  184. rfc1951 < "1.0.0"
  185. sarek >= "20210823"
  186. sarif >= "0.2.1"
  187. satyrographos >= "0.0.2.7"
  188. semantic_version
  189. sexp_pretty
  190. sill >= "1.3.1"
  191. simple-diff
  192. slug
  193. soupault
  194. spoc >= "20210823"
  195. sqlexpr >= "0.7.1" & < "0.9.0"
  196. swagger
  197. tar < "2.2.0"
  198. tar-format >= "0.2.0"
  199. tar-mirage < "2.2.0"
  200. tar-unix < "2.2.0"
  201. testrunner
  202. tezos-base < "7.4"
  203. tezos-clic < "8.0" | >= "13.0"
  204. tezos-protocol-compiler = "10.2" | = "13.0"
  205. tezos-stdlib-unix >= "7.4"
  206. tezt
  207. timere-parse
  208. touist >= "3.5.0"
  209. tyre >= "0.4"
  210. tyxml >= "4.0.0"
  211. tyxml-syntax
  212. uri < "4.0.0"
  213. uri-re
  214. user-agent-parser
  215. user-setup
  216. uuuu
  217. validate
  218. vendredi
  219. vhd-tool >= "0.12.0"
  220. webmachine
  221. xapi-idl
  222. xe
  223. xen-api-client >= "0.9.6"
  224. xtmpl >= "0.15.0"

Conflicts

None

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