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 (22)

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-1.11.0.tbz
sha256=01fc244780c0f6be72ae796b1fb750f367de18624fd75d07ee79782ed6df8d4f
sha512=3e3712cc1266ec1f27620f3508ea2ebba338f4083b07d8a69dccee1facfdc1971a6c39f9deea664d2a62fd7f2cfd2eae816ca4c274acfadaee992a3befc4b757

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: 23 Aug 2023

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 >= "4.03"

Dev Dependencies (1)

  1. ounit 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. caisar
  32. calculon >= "0.2"
  33. calculon-web
  34. caldav
  35. calendar >= "3.0.0"
  36. camlp5 >= "8.00.05"
  37. camlp5-buildscripts
  38. camyll
  39. caqti >= "1.7.0"
  40. catala
  41. ccss >= "1.6"
  42. chamo >= "4.0"
  43. cinaps >= "v0.10.0"
  44. cohttp
  45. coin
  46. colibri2
  47. commons
  48. conan >= "0.0.5"
  49. core_bench >= "v0.9.0"
  50. core_extended >= "v0.10.0"
  51. cosovo
  52. cow < "1.2.2"
  53. cowabloga >= "0.4.0"
  54. cucumber
  55. cuid
  56. current
  57. current_web >= "0.4"
  58. daypack-lib
  59. debian-formats
  60. decompress >= "0.8" & < "1.0.0"
  61. dkml-install-installer >= "0.4.0"
  62. dns < "4.0.0"
  63. dog < "0.2.1"
  64. doi2bib >= "0.5.1"
  65. dose
  66. dose3
  67. dune-release >= "0.2.0"
  68. duppy >= "0.9.4"
  69. elpi
  70. expect_test_helpers_core
  71. expect_test_helpers_kernel
  72. ez_file
  73. ez_search
  74. fat-filesystem != "0.12.0"
  75. frag
  76. gensqlite
  77. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  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. learn-ocaml >= "0.13.0"
  110. libres3 >= "0.3"
  111. lipsum
  112. magic-trace
  113. mbr-format < "1.0.0"
  114. mdx
  115. mehari
  116. message-switch
  117. mirage >= "0.10.0" & < "2.4.0"
  118. mirage-bootvar-xen < "0.3.2"
  119. mirage-www < "1.0.0"
  120. mparser-re
  121. mustache < "2.0.0"
  122. naboris
  123. netsnmp
  124. ninja_utils
  125. obelisk >= "0.5.0"
  126. ocaml-lsp-server >= "1.7.0"
  127. ocamlformat >= "0.11.0"
  128. ocamlformat-rpc < "0.21.0"
  129. ocp-build >= "1.99.21"
  130. ocp-index >= "1.0.2"
  131. ocsigen-start >= "1.7.0"
  132. ocsigenserver >= "5.1.0"
  133. octez-bls12-381-signature
  134. octez-libs
  135. odoc >= "2.0.0" & < "2.1.0"
  136. opam-bin >= "0.9.5" & < "1.1.0"
  137. opam-build-revdeps
  138. opam-client >= "2.0.0~rc2"
  139. opam-compiler
  140. opam-core
  141. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  142. opam-lib
  143. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  144. opam-state >= "2.2.0~alpha"
  145. opam2web >= "1.3.0"
  146. opam_bin_lib
  147. operf-macro
  148. opium >= "0.13.1"
  149. opium_kernel
  150. oranger
  151. orun
  152. ostap
  153. ozulip
  154. pa_ppx_parsetree
  155. pa_ppx_regexp >= "0.02"
  156. pa_ppx_string
  157. patdiff >= "v0.12.0"
  158. pgocaml >= "2.3"
  159. pgx
  160. plato
  161. podge >= "0.3"
  162. ppx_css < "v0.17.0"
  163. ppx_cstubs
  164. ppx_expect >= "113.33.00" & < "v0.17.0"
  165. ppx_implicits >= "0.1.0"
  166. ppx_minidebug >= "1.0.0"
  167. ppx_orakuda >= "3.0.0"
  168. ppx_regexp >= "0.3.2"
  169. ppx_sqlexpr
  170. ppx_test >= "1.1.0"
  171. ppx_tyre
  172. ppxlib >= "0.21.0"
  173. prometheus >= "0.2"
  174. prometheus-app >= "0.2"
  175. pyml_bindgen >= "0.3.1"
  176. rdf >= "0.12.0"
  177. re_parser
  178. reason < "1.7.4"
  179. receive-mail
  180. redis >= "0.2.1"
  181. regenerate
  182. rfc1951 < "1.0.0"
  183. sarek >= "20210823"
  184. sarif >= "0.2.1"
  185. satyrographos >= "0.0.2.7"
  186. semantic_version
  187. sexp_pretty
  188. sill >= "1.3.1"
  189. simple-diff
  190. slug
  191. soupault
  192. spoc >= "20210823"
  193. sqlexpr >= "0.7.1" & < "0.9.0"
  194. swagger
  195. tar < "2.2.0"
  196. tar-format >= "0.2.0"
  197. tar-mirage < "2.2.0"
  198. tar-unix < "2.2.0"
  199. testrunner
  200. tezos-base < "7.4"
  201. tezos-clic < "8.0" | >= "13.0"
  202. tezos-protocol-compiler = "10.2" | = "13.0"
  203. tezos-stdlib-unix >= "7.4"
  204. tezt
  205. timere-parse
  206. touist >= "3.5.0"
  207. tyre >= "0.4"
  208. tyxml >= "4.0.0"
  209. tyxml-syntax
  210. uri < "4.0.0"
  211. uri-re
  212. user-agent-parser
  213. user-setup
  214. uuuu
  215. validate
  216. vendredi
  217. vhd-tool >= "0.12.0"
  218. webmachine
  219. xapi-idl
  220. xe
  221. xen-api-client >= "0.9.6"
  222. xtmpl >= "0.15.0"

Conflicts

None

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