package re

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

Install

Dune Dependency

github.com Readme Changelog LGPL-2.0-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-1.10.4.tbz
sha256=83eb3e4300aa9b1dc7820749010f4362ea83524742130524d78c20ce99ca747c
sha512=92b05cf92c389fa8c753f2acca837b15dd05a4a2e8e2bec7a269d2e14c35b1a786d394258376648f80b4b99250ba1900cfe68230b8385aeac153149d9ce56099

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: 27 Apr 2022

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 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" & < "8.02.01"
  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. learn-ocaml >= "0.13.0"
  108. libres3 >= "0.3"
  109. lipsum
  110. magic-trace
  111. mbr-format < "1.0.0"
  112. mdx
  113. mehari
  114. message-switch
  115. mirage >= "0.10.0" & < "2.4.0"
  116. mirage-bootvar-xen < "0.3.2"
  117. mirage-www < "1.0.0"
  118. mparser-re
  119. mustache < "2.0.0"
  120. naboris
  121. netsnmp
  122. ninja_utils
  123. obelisk >= "0.5.0"
  124. ocaml-lsp-server >= "1.7.0"
  125. ocamlformat >= "0.11.0"
  126. ocamlformat-rpc < "0.21.0"
  127. ocp-build >= "1.99.21"
  128. ocp-index >= "1.0.2"
  129. ocsigen-start >= "1.7.0"
  130. octez-bls12-381-signature
  131. octez-libs
  132. odoc >= "2.0.0" & < "2.1.0"
  133. opam-bin >= "0.9.5" & < "1.1.0"
  134. opam-build-revdeps
  135. opam-client >= "2.0.0~rc2"
  136. opam-compiler
  137. opam-core
  138. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  139. opam-lib
  140. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  141. opam-state >= "2.2.0~alpha"
  142. opam2web >= "1.3.0"
  143. opam_bin_lib
  144. operf-macro
  145. opium >= "0.13.1"
  146. opium_kernel
  147. oranger
  148. orun
  149. ostap
  150. ozulip
  151. pa_ppx_regexp < "0.02"
  152. pa_ppx_string
  153. patdiff >= "v0.12.0"
  154. pgocaml >= "2.3"
  155. pgx
  156. plato
  157. podge >= "0.3"
  158. ppx_css
  159. ppx_cstubs
  160. ppx_expect >= "113.33.00"
  161. ppx_implicits >= "0.1.0"
  162. ppx_minidebug >= "1.0.0"
  163. ppx_orakuda >= "3.0.0"
  164. ppx_regexp >= "0.3.2"
  165. ppx_sqlexpr
  166. ppx_test >= "1.1.0"
  167. ppx_tyre
  168. ppxlib >= "0.21.0"
  169. prometheus >= "0.2"
  170. prometheus-app >= "0.2"
  171. pyml_bindgen >= "0.3.1"
  172. rdf >= "0.12.0" & < "1.0.0"
  173. re_parser
  174. reason < "1.7.4"
  175. receive-mail
  176. redis >= "0.2.1"
  177. regenerate
  178. rfc1951 < "1.0.0"
  179. sarek >= "20210823"
  180. sarif >= "0.2.1"
  181. satyrographos >= "0.0.2.7"
  182. semantic_version
  183. sexp_pretty
  184. sill >= "1.3.1"
  185. simple-diff
  186. slug
  187. soupault
  188. spoc >= "20210823"
  189. sqlexpr >= "0.7.1" & < "0.9.0"
  190. swagger
  191. tar < "2.2.0"
  192. tar-format >= "0.2.0"
  193. tar-mirage < "2.2.0"
  194. tar-unix < "2.2.0"
  195. testrunner
  196. tezos-base < "7.4"
  197. tezos-clic < "8.0" | >= "13.0"
  198. tezos-protocol-compiler = "10.2" | = "13.0"
  199. tezos-stdlib-unix >= "7.4"
  200. tezt
  201. timere-parse
  202. touist >= "3.5.0"
  203. tyre >= "0.4"
  204. tyxml >= "4.0.0"
  205. tyxml-syntax
  206. uri < "4.0.0"
  207. uri-re
  208. user-agent-parser
  209. user-setup
  210. uuuu
  211. validate
  212. vendredi
  213. vhd-tool >= "0.12.0"
  214. webmachine
  215. xapi-idl
  216. xe
  217. xen-api-client >= "0.9.6"
  218. xtmpl >= "0.15.0"

Conflicts

None