package re

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

Install 

dune-project
 Dependency

github.com Readme Changelog LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception License Edit opam file Versions (20)

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. Build status

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
  2. alcotest-async
  3. alcotest-lwt
  4. alcotest-mirage
  5. alice
  6. ansifmt >= "1.0.0~pre2"
  7. atd >= "2.2.1"
  8. atdcpp
  9. atdd
  10. atdgen >= "2.3.3"
  11. atdgen-runtime = "2.2.1"
  12. atdj >= "2.2.1"
  13. atdpy >= "2.4.1"
  14. atds < "2.3.3"
  15. atdts
  16. aws-config
  17. awsm-codegen
  18. BetterErrors
  19. bancos
  20. bap-byteweight-frontend
  21. bap-callgraph-collator
  22. bap-fsi-benchmark
  23. bap-ida
  24. bap-objdump
  25. bap-print >= "2.2.0"
  26. bap-radare2
  27. benchpress
  28. bibfmt
  29. bio_io >= "0.5.1"
  30. biocaml
  31. bistro < "0.6.0"
  32. bonsai >= "v0.15.0"
  33. caisar >= "4.0"
  34. calculon
  35. calculon-web
  36. caldav
  37. calendar >= "3.0.0"
  38. camlp5 >= "8.02.01"
  39. camlp5-buildscripts
  40. camyll
  41. caqti >= "1.7.0"
  42. catala
  43. chamo
  44. cinaps >= "v0.10.0"
  45. cohttp
  46. coin < "0.1.5"
  47. colibri2
  48. commons
  49. conan >= "0.0.6"
  50. core_bench
  51. core_extended
  52. cosovo
  53. cowabloga >= "0.4.0"
  54. crs
  55. cucumber
  56. cuid
  57. current
  58. current_web
  59. daypack-lib
  60. debian-formats
  61. decompress < "1.0.0"
  62. dkml-install-installer >= "0.4.0"
  63. dns < "4.4.1"
  64. doi2bib
  65. dose3
  66. dune-glob >= "3.21.0"
  67. dune-release >= "0.2.0"
  68. dunolint >= "0.0.20251006"
  69. dunolint-lib
  70. dunolint-lib-base
  71. duppy >= "0.9.4"
  72. elpi
  73. expect >= "0.1.0"
  74. expect_test_helpers_core
  75. expect_test_helpers_kernel
  76. ez_file
  77. ez_search
  78. fat-filesystem
  79. git-split < "1.0.0"
  80. gpiod
  81. graphql_parser >= "0.11.0"
  82. hardcaml_verify
  83. hardcaml_waveterm
  84. hardcaml_xilinx_components
  85. hlarp >= "0.0.3"
  86. horned_worm
  87. humane-re
  88. icalendar
  89. index
  90. index-bench
  91. irmin-bench
  92. jingoo >= "1.2.21"
  93. js_of_ocaml >= "3.10.0"
  94. js_of_ocaml-compiler >= "3.10.0"
  95. js_of_ocaml-lwt >= "3.10.0"
  96. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  97. js_of_ocaml-ppx >= "3.10.0"
  98. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  99. js_of_ocaml-toplevel >= "3.10.0"
  100. js_of_ocaml-tyxml >= "3.10.0"
  101. jsonschema
  102. jwt
  103. jwto
  104. kappa-library
  105. kubecaml
  106. labrys
  107. lastfm >= "0.3.4"
  108. ldap >= "2.5.1"
  109. learn-ocaml
  110. ledes
  111. lipsum
  112. liquidsoap >= "2.3.3"
  113. liquidsoap-core >= "2.3.0"
  114. liquidsoap-lang >= "2.3.0"
  115. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  116. MlFront_Core >= "2.4.2.30"
  117. MlFront_ZipFile
  118. magic-trace
  119. mdx
  120. mehari
  121. mparser-re
  122. naboris
  123. netsnmp
  124. ninja_utils
  125. nx-text
  126. obelisk >= "0.5.0"
  127. ocaml-lsp-server >= "1.9.0"
  128. ocamlformat >= "0.11.0"
  129. ocamlformat-mlx
  130. ocamlformat-rpc < "0.21.0"
  131. ocamlmig
  132. ocp-build
  133. ocp-index
  134. ocsigen-start
  135. ocsigenserver >= "5.1.0"
  136. octez-bls12-381-signature
  137. octez-libs
  138. opam-bin >= "0.9.5" & < "1.1.0"
  139. opam-client
  140. opam-compiler
  141. opam-core
  142. opam-format >= "2.0.8" & != "2.1.0~beta4"
  143. opam-lib
  144. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  145. opam-state >= "2.2.0"
  146. opam_bin_lib
  147. opium
  148. opium_kernel
  149. oranger
  150. orun
  151. ostap
  152. ozulip
  153. pa_ppx_parsetree
  154. pa_ppx_regexp >= "0.04"
  155. pa_ppx_string
  156. patdiff
  157. pgocaml >= "2.3"
  158. pgx
  159. plato
  160. podge >= "0.3"
  161. ppx_css < "v0.17.0"
  162. ppx_cstubs
  163. ppx_expect < "v0.17.0"
  164. ppx_expect_nobase < "v0.17.3.0"
  165. ppx_minidebug >= "1.6.0"
  166. ppx_regexp >= "0.3.2"
  167. ppx_test
  168. ppx_tyre
  169. ppxlib >= "0.21.1"
  170. prometheus >= "0.2"
  171. prometheus-app
  172. pyml_bindgen >= "0.3.1"
  173. raga
  174. rdf >= "0.12.0"
  175. re_parser
  176. redis
  177. regenerate
  178. regrade
  179. rfc1951 < "1.0.0"
  180. safemoney >= "0.3.0"
  181. saga
  182. sarek
  183. sarif >= "0.2.1"
  184. satyrographos >= "0.0.2.7"
  185. semantic_version
  186. sexp_pretty
  187. shakuhachi
  188. simple-diff
  189. slug
  190. snf_mcp
  191. soupault
  192. spoc
  193. statocaml_profile
  194. swagger
  195. talon
  196. testo
  197. testo-lwt
  198. testo-util
  199. tezos-clic >= "16.0"
  200. tezos-stdlib-unix
  201. tezt
  202. timere-parse
  203. touist >= "3.5.0"
  204. tyre >= "0.4"
  205. tyxml >= "4.2.0"
  206. tyxml-syntax
  207. uri < "4.0.0"
  208. uri-re
  209. user-agent-parser
  210. user-setup
  211. uuuu < "0.4.0"
  212. validate
  213. vendredi
  214. wasm_of_ocaml-compiler
  215. webmachine
  216. xtmpl >= "0.18.0"

Conflicts

None