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. dns < "4.0.0"
  62. dog < "0.2.1"
  63. doi2bib >= "0.5.1"
  64. dose
  65. dose3
  66. dune-release >= "0.2.0"
  67. duppy >= "0.9.4"
  68. elpi
  69. expect_test_helpers_core
  70. expect_test_helpers_kernel
  71. ez_file
  72. ez_search
  73. fat-filesystem != "0.12.0"
  74. frag
  75. gensqlite
  76. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  77. gpiod
  78. graphql_parser >= "0.11.0"
  79. hardcaml_verify
  80. hardcaml_waveterm
  81. hardcaml_xilinx_components
  82. hlarp >= "0.0.3"
  83. horned_worm
  84. http_router
  85. humane-re
  86. icalendar
  87. imaplet-lwt >= "0.1.9"
  88. index
  89. index-bench
  90. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  91. irmin-bench >= "2.4.0"
  92. iso-filesystem
  93. jingoo >= "1.2.21"
  94. js_of_ocaml >= "3.10.0"
  95. js_of_ocaml-compiler >= "3.10.0"
  96. js_of_ocaml-lwt >= "3.10.0"
  97. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  98. js_of_ocaml-ppx >= "3.10.0"
  99. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  100. js_of_ocaml-toplevel >= "3.10.0"
  101. js_of_ocaml-tyxml >= "3.10.0"
  102. jwt
  103. jwto
  104. kappa-library
  105. kubecaml
  106. labrys
  107. lastfm >= "0.3.4"
  108. learn-ocaml >= "0.13.0"
  109. libres3 >= "0.3"
  110. lipsum
  111. magic-trace
  112. mbr-format < "1.0.0"
  113. mdx
  114. mehari
  115. message-switch
  116. mirage >= "0.10.0" & < "2.4.0"
  117. mirage-bootvar-xen < "0.3.2"
  118. mirage-www < "1.0.0"
  119. mparser-re
  120. mustache < "2.0.0"
  121. naboris
  122. netsnmp
  123. ninja_utils
  124. obelisk >= "0.5.0"
  125. ocaml-lsp-server >= "1.7.0"
  126. ocamlformat >= "0.11.0"
  127. ocamlformat-rpc < "0.21.0"
  128. ocp-build >= "1.99.21"
  129. ocp-index >= "1.0.2"
  130. ocsigen-start >= "1.7.0"
  131. ocsigenserver >= "5.1.0"
  132. octez-bls12-381-signature
  133. octez-libs
  134. odoc >= "2.0.0" & < "2.1.0"
  135. opam-bin >= "0.9.5" & < "1.1.0"
  136. opam-build-revdeps
  137. opam-client >= "2.0.0~rc2"
  138. opam-compiler
  139. opam-core
  140. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  141. opam-lib
  142. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  143. opam-state >= "2.2.0~alpha"
  144. opam2web >= "1.3.0"
  145. opam_bin_lib
  146. operf-macro
  147. opium >= "0.13.1"
  148. opium_kernel
  149. oranger
  150. orun
  151. ostap
  152. ozulip
  153. pa_ppx_parsetree
  154. pa_ppx_regexp >= "0.02"
  155. pa_ppx_string
  156. patdiff >= "v0.12.0"
  157. pgocaml >= "2.3"
  158. pgx
  159. plato
  160. podge >= "0.3"
  161. ppx_css
  162. ppx_cstubs
  163. ppx_expect >= "113.33.00"
  164. ppx_implicits >= "0.1.0"
  165. ppx_minidebug >= "1.0.0"
  166. ppx_orakuda >= "3.0.0"
  167. ppx_regexp >= "0.3.2"
  168. ppx_sqlexpr
  169. ppx_test >= "1.1.0"
  170. ppx_tyre
  171. ppxlib >= "0.21.0"
  172. prometheus >= "0.2"
  173. prometheus-app >= "0.2"
  174. pyml_bindgen >= "0.3.1"
  175. rdf >= "0.12.0"
  176. re_parser
  177. reason < "1.7.4"
  178. receive-mail
  179. redis >= "0.2.1"
  180. regenerate
  181. rfc1951 < "1.0.0"
  182. sarek >= "20210823"
  183. sarif >= "0.2.1"
  184. satyrographos >= "0.0.2.7"
  185. semantic_version
  186. sexp_pretty
  187. sill >= "1.3.1"
  188. simple-diff
  189. slug
  190. soupault
  191. spoc >= "20210823"
  192. sqlexpr >= "0.7.1" & < "0.9.0"
  193. swagger
  194. tar < "2.2.0"
  195. tar-format >= "0.2.0"
  196. tar-mirage < "2.2.0"
  197. tar-unix < "2.2.0"
  198. testrunner
  199. tezos-base < "7.4"
  200. tezos-clic < "8.0" | >= "13.0"
  201. tezos-protocol-compiler = "10.2" | = "13.0"
  202. tezos-stdlib-unix >= "7.4"
  203. tezt
  204. timere-parse
  205. touist >= "3.5.0"
  206. tyre >= "0.4"
  207. tyxml >= "4.0.0"
  208. tyxml-syntax
  209. uri < "4.0.0"
  210. uri-re
  211. user-agent-parser
  212. user-setup
  213. uuuu
  214. validate
  215. vendredi
  216. vhd-tool >= "0.12.0"
  217. webmachine
  218. xapi-idl
  219. xe
  220. xen-api-client >= "0.9.6"
  221. xtmpl >= "0.15.0"

Conflicts

None