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 (18)

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
  2. alcotest-async >= "1.3.0"
  3. alcotest-lwt >= "1.3.0"
  4. alcotest-mirage >= "1.3.0"
  5. atd >= "2.2.1"
  6. atdcpp
  7. atdd
  8. atdgen >= "2.3.3"
  9. atdgen-runtime = "2.2.1"
  10. atdj >= "2.2.1"
  11. atdpy >= "2.4.1"
  12. atds < "2.3.3"
  13. atdts
  14. aws-config
  15. awsm-codegen
  16. BetterErrors
  17. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. benchpress
  25. bio_io >= "0.5.1"
  26. biocaml
  27. bistro < "0.6.0"
  28. bonsai >= "v0.15.0"
  29. calculon
  30. calculon-web
  31. caldav
  32. calendar >= "3.0.0"
  33. camlp5 >= "8.00.05"
  34. camlp5-buildscripts
  35. camyll
  36. caqti >= "1.7.0"
  37. catala
  38. chamo
  39. cinaps >= "v0.10.0"
  40. cohttp
  41. coin
  42. colibri2
  43. commons
  44. core_bench
  45. core_extended
  46. cosovo
  47. cowabloga >= "0.4.0"
  48. cucumber
  49. cuid
  50. current
  51. current_web >= "0.4"
  52. daypack-lib
  53. debian-formats
  54. decompress < "1.0.0"
  55. dkml-install-installer >= "0.4.0"
  56. dns < "4.0.0"
  57. doi2bib >= "0.5.1"
  58. dose3
  59. dune-release >= "0.2.0"
  60. duppy >= "0.9.4"
  61. elpi
  62. expect >= "0.1.0"
  63. expect_test_helpers_core
  64. expect_test_helpers_kernel
  65. ez_file
  66. ez_search
  67. fat-filesystem
  68. git >= "1.9.0" & < "2.0.0"
  69. git-split < "1.0.0"
  70. gpiod
  71. graphql_parser >= "0.11.0"
  72. hardcaml_verify
  73. hardcaml_waveterm
  74. hardcaml_xilinx_components
  75. hlarp >= "0.0.3"
  76. horned_worm
  77. humane-re
  78. icalendar
  79. index
  80. index-bench
  81. irmin-bench >= "2.4.0"
  82. jingoo >= "1.2.21"
  83. js_of_ocaml >= "3.10.0"
  84. js_of_ocaml-compiler >= "3.10.0"
  85. js_of_ocaml-lwt >= "3.10.0"
  86. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  87. js_of_ocaml-ppx >= "3.10.0"
  88. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  89. js_of_ocaml-toplevel >= "3.10.0"
  90. js_of_ocaml-tyxml >= "3.10.0"
  91. jwt
  92. jwto
  93. kappa-library
  94. kubecaml
  95. labrys
  96. lastfm >= "0.3.4"
  97. ldap >= "2.5.1"
  98. learn-ocaml
  99. lipsum
  100. liquidsoap >= "2.3.1"
  101. liquidsoap-core >= "2.3.0"
  102. liquidsoap-lang >= "2.3.0"
  103. MlFront_Cli >= "2.1.4~prerel2"
  104. magic-trace
  105. mdx
  106. mehari
  107. mirage-bootvar-xen < "0.3.2"
  108. mparser-re
  109. naboris
  110. netsnmp
  111. ninja_utils
  112. obelisk >= "0.5.0"
  113. ocaml-lsp-server >= "1.7.0"
  114. ocamlformat >= "0.11.0"
  115. ocamlformat-mlx
  116. ocamlformat-rpc < "0.21.0"
  117. ocamlmig
  118. ocp-build
  119. ocp-index
  120. ocsigen-start
  121. ocsigenserver >= "5.1.0"
  122. octez-bls12-381-signature
  123. octez-libs
  124. odoc >= "2.0.0" & < "2.1.0"
  125. opam-bin >= "0.9.5" & < "1.1.0"
  126. opam-client
  127. opam-compiler
  128. opam-core
  129. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  130. opam-lib
  131. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  132. opam-state >= "2.2.0~alpha"
  133. opam_bin_lib
  134. opium
  135. opium_kernel
  136. oranger
  137. orun
  138. ostap
  139. ozulip
  140. pa_ppx_parsetree
  141. pa_ppx_regexp >= "0.04"
  142. pa_ppx_string
  143. patdiff
  144. pgocaml >= "2.3"
  145. pgx
  146. plato
  147. podge >= "0.3"
  148. ppx_css < "v0.17.0"
  149. ppx_cstubs
  150. ppx_expect < "v0.17.0"
  151. ppx_expect_nobase
  152. ppx_minidebug >= "1.0.0"
  153. ppx_regexp >= "0.3.2"
  154. ppx_test
  155. ppx_tyre
  156. ppxlib >= "0.21.0"
  157. prometheus >= "0.2"
  158. prometheus-app
  159. pyml_bindgen >= "0.3.1"
  160. rdf >= "0.12.0"
  161. re_parser
  162. redis
  163. regenerate
  164. rfc1951 < "1.0.0"
  165. sarek
  166. sarif >= "0.2.1"
  167. satyrographos >= "0.0.2.7"
  168. semantic_version
  169. sexp_pretty
  170. simple-diff
  171. slug
  172. soupault
  173. spoc
  174. swagger
  175. tar < "2.2.0"
  176. tar-mirage < "2.2.1"
  177. tar-unix < "2.2.0"
  178. testo
  179. testo-lwt
  180. testo-util
  181. tezos-clic >= "16.0"
  182. tezos-stdlib-unix
  183. tezt
  184. timere-parse
  185. touist >= "3.5.0"
  186. tyre >= "0.4"
  187. tyxml >= "4.2.0"
  188. tyxml-syntax
  189. uri < "4.0.0"
  190. uri-re
  191. user-agent-parser
  192. user-setup
  193. uuuu
  194. validate
  195. vendredi
  196. wasm_of_ocaml-compiler
  197. webmachine
  198. xtmpl >= "0.18.0"

Conflicts

None

OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct