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

Conflicts

None