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. atd-jsonlike
  9. atdcpp
  10. atdd
  11. atdgen >= "2.3.3"
  12. atdgen-runtime = "2.2.1"
  13. atdj >= "2.2.1"
  14. atdpy >= "2.4.1"
  15. atds < "2.3.3"
  16. atdts
  17. aws-config
  18. awsm-codegen
  19. BetterErrors
  20. bancos
  21. bap-byteweight-frontend
  22. bap-callgraph-collator
  23. bap-fsi-benchmark
  24. bap-ida
  25. bap-objdump
  26. bap-print >= "2.2.0"
  27. bap-radare2
  28. benchpress
  29. bibfmt
  30. bio_io >= "0.5.1"
  31. biocaml
  32. bistro < "0.6.0"
  33. bonsai >= "v0.15.0"
  34. brot
  35. caisar >= "4.0"
  36. calculon
  37. calculon-web
  38. caldav
  39. calendar >= "3.0.0"
  40. camlp5 >= "8.02.01"
  41. camlp5-buildscripts
  42. camyll
  43. caqti >= "1.7.0"
  44. catala
  45. chamo
  46. ciao_lwt
  47. cinaps >= "v0.10.0"
  48. cohttp
  49. coin < "0.1.5"
  50. colibri2
  51. commons
  52. conan >= "0.0.6"
  53. core_bench
  54. core_extended
  55. cosovo
  56. cowabloga >= "0.4.0"
  57. crs
  58. cucumber
  59. cuid
  60. current
  61. current_web
  62. daypack-lib
  63. debian-formats
  64. decompress < "1.0.0"
  65. dns < "4.4.1"
  66. doi2bib
  67. dose3
  68. dune-glob >= "3.21.0"
  69. dune-release >= "0.2.0"
  70. dunolint >= "0.0.20251006"
  71. dunolint-lib
  72. dunolint-lib-base
  73. duppy >= "0.9.5"
  74. elpi
  75. expect >= "0.1.0"
  76. expect_test_helpers_core
  77. expect_test_helpers_kernel
  78. ez_file
  79. ez_search
  80. fat-filesystem
  81. git-split < "1.0.0"
  82. gpiod
  83. graphql_parser >= "0.11.0"
  84. hardcaml_verify
  85. hardcaml_waveterm
  86. hardcaml_xilinx_components
  87. hlarp >= "0.0.3"
  88. horned_worm
  89. humane-re
  90. icalendar
  91. index
  92. index-bench
  93. irmin-bench
  94. jingoo >= "1.2.21"
  95. js_of_ocaml >= "3.10.0"
  96. js_of_ocaml-compiler >= "3.10.0"
  97. js_of_ocaml-lwt >= "3.10.0"
  98. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  99. js_of_ocaml-ppx >= "3.10.0"
  100. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  101. js_of_ocaml-toplevel >= "3.10.0"
  102. js_of_ocaml-tyxml >= "3.10.0"
  103. jsonschema
  104. jsonschema-core
  105. jsonschema-validation
  106. jwt
  107. jwto
  108. kappa-library
  109. kubecaml
  110. labrys
  111. lastfm >= "0.3.4"
  112. ldap >= "2.5.1"
  113. learn-ocaml
  114. ledes
  115. lipsum
  116. liquidsoap >= "2.3.3"
  117. liquidsoap-core >= "2.3.0"
  118. liquidsoap-lang >= "2.3.0"
  119. lwt_lint
  120. lwt_ppx_to_let_syntax
  121. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  122. MlFront_Core >= "2.4.2.30"
  123. MlFront_ZipFile
  124. magic-trace
  125. mdx
  126. mehari
  127. mparser-re
  128. naboris
  129. netsnmp
  130. ninja_utils
  131. nx-text
  132. obelisk >= "0.5.0"
  133. ocaml-lsp-server >= "1.9.0"
  134. ocamlformat >= "0.11.0"
  135. ocamlformat-mlx
  136. ocamlformat-rpc < "0.21.0"
  137. ocamlmig
  138. ocgtk
  139. ocp-build
  140. ocp-index
  141. ocsigen-start
  142. ocsigenserver >= "5.1.0"
  143. opam-bin >= "0.9.5" & < "1.1.0"
  144. opam-client
  145. opam-compiler
  146. opam-core
  147. opam-format >= "2.0.8" & != "2.1.0~beta4"
  148. opam-lib
  149. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  150. opam-state >= "2.2.0"
  151. opam_bin_lib
  152. opium
  153. opium_kernel
  154. oranger
  155. orun
  156. ostap
  157. ozulip
  158. pa_ppx_parsetree
  159. pa_ppx_regexp >= "0.04"
  160. pa_ppx_string
  161. parseff
  162. patdiff
  163. pgocaml >= "2.3"
  164. pgx
  165. plato
  166. podge >= "0.3"
  167. ppx_css < "v0.17.0"
  168. ppx_cstubs
  169. ppx_expect < "v0.17.0"
  170. ppx_expect_nobase < "v0.17.3.0"
  171. ppx_mikmatch
  172. ppx_minidebug >= "1.6.0"
  173. ppx_regexp >= "0.3.2"
  174. ppx_test
  175. ppx_tyre
  176. ppxlib >= "0.21.1"
  177. prometheus >= "0.2"
  178. prometheus-app
  179. pyml_bindgen >= "0.3.1"
  180. raga
  181. rdf >= "0.12.0"
  182. re_parser
  183. redis
  184. regenerate
  185. regrade
  186. rfc1951 < "1.0.0"
  187. safemoney >= "0.3.0"
  188. saga
  189. sarek
  190. sarif >= "0.2.1"
  191. satyrographos >= "0.0.2.7"
  192. semantic_version
  193. sexp_pretty
  194. shakuhachi
  195. simple-diff
  196. slug
  197. smtml >= "0.21.0"
  198. snf_mcp
  199. soupault
  200. spectrum >= "0.7.0"
  201. spectrum_capabilities
  202. spectrum_palette_ppx
  203. spectrum_tools
  204. spoc
  205. statocaml_profile
  206. swagger
  207. talon < "1.0.0~alpha3"
  208. testcontainers
  209. testo
  210. testo-lwt
  211. testo-util
  212. tezt
  213. timere-parse
  214. touist >= "3.5.0"
  215. tyre >= "0.4"
  216. tyxml >= "4.2.0"
  217. tyxml-syntax
  218. uri < "4.0.0"
  219. uri-re
  220. user-agent-parser
  221. user-setup
  222. uuuu < "0.4.0"
  223. validate
  224. vendredi
  225. wasm_of_ocaml-compiler
  226. webmachine
  227. xtmpl >= "0.18.0"

Conflicts

None