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. awso
  20. BetterErrors
  21. bancos
  22. bap-byteweight-frontend
  23. bap-callgraph-collator
  24. bap-fsi-benchmark
  25. bap-ida
  26. bap-objdump
  27. bap-print
  28. bap-radare2
  29. bibfmt
  30. bio_io >= "0.5.1"
  31. biocaml
  32. bonsai >= "v0.15.0"
  33. brot
  34. caisar >= "4.0"
  35. calculon
  36. calculon-web
  37. caldav
  38. calendar >= "3.0.0"
  39. camlp5 >= "8.02.01"
  40. camlp5-buildscripts
  41. camyll
  42. caqti >= "1.7.0"
  43. cascade
  44. catala
  45. catala-format >= "1.2.0"
  46. chamo
  47. ciao_lwt
  48. cinaps
  49. cohttp
  50. coin < "0.1.5"
  51. colibri2
  52. commons
  53. conan >= "0.0.6"
  54. core_bench
  55. core_extended
  56. cosovo
  57. cowabloga >= "0.4.0"
  58. crs
  59. cucumber
  60. cuid
  61. current
  62. current_web
  63. daypack-lib
  64. debian-formats
  65. decompress < "1.0.0"
  66. dns < "4.4.1"
  67. docfd >= "13.0.0"
  68. doi2bib
  69. dose3
  70. dune-glob >= "3.21.0"
  71. dune-release >= "0.2.0"
  72. dunolint >= "0.0.20251006"
  73. dunolint-lib
  74. dunolint-lib-base
  75. duppy >= "0.9.5"
  76. elpi
  77. expect >= "0.1.0"
  78. expect_test_helpers_core
  79. expect_test_helpers_kernel
  80. ez_file
  81. ez_search
  82. fat-filesystem
  83. git-split < "1.0.0"
  84. gpiod
  85. graphql_parser >= "0.11.0"
  86. hardcaml_verify
  87. hardcaml_waveterm
  88. hardcaml_xilinx_components
  89. hlarp >= "0.0.3"
  90. humane-re
  91. icalendar
  92. index
  93. index-bench
  94. irmin-bench
  95. jingoo >= "1.2.21"
  96. js_of_ocaml >= "3.10.0"
  97. js_of_ocaml-compiler >= "3.10.0"
  98. js_of_ocaml-lwt >= "3.10.0"
  99. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  100. js_of_ocaml-ppx >= "3.10.0"
  101. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  102. js_of_ocaml-toplevel >= "3.10.0"
  103. js_of_ocaml-tyxml >= "3.10.0"
  104. jsonschema
  105. jsonschema-core
  106. jsonschema-validation
  107. jwt
  108. jwto
  109. kappa-library
  110. kubecaml
  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_ppx_to_let_syntax
  120. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  121. MlFront_Core >= "2.4.2.30"
  122. MlFront_ZipFile
  123. magic-trace
  124. mdx
  125. mehari
  126. mnet-cli >= "0.0.3"
  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
  135. ocamlformat-mlx
  136. ocamlformat-rpc < "0.21.0"
  137. ocamlmig
  138. ocgtk < "0.1~preview2"
  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. playwright
  167. podge >= "0.3"
  168. ppx_css < "v0.17.0"
  169. ppx_cstubs
  170. ppx_expect < "v0.17.0"
  171. ppx_expect_nobase = "v0.17.2.2"
  172. ppx_mikmatch
  173. ppx_minidebug >= "1.6.0"
  174. ppx_regexp >= "0.3.2"
  175. ppx_test
  176. ppx_tyre
  177. ppxlib >= "0.21.1"
  178. prometheus >= "0.2"
  179. prometheus-app
  180. pyml_bindgen >= "0.3.1"
  181. raga
  182. rdf
  183. re_parser
  184. redis
  185. regrade
  186. rfc1951 < "1.0.0"
  187. safemoney >= "0.3.0"
  188. saga
  189. sarek
  190. sarif >= "0.2.1"
  191. satyrographos
  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. stem
  207. swagger
  208. talon < "1.0.0~alpha3"
  209. testcontainers
  210. testo
  211. testo-lwt
  212. testo-util
  213. tezt
  214. timere-parse
  215. touist >= "3.5.0"
  216. tyre >= "0.4"
  217. tyxml >= "4.2.0"
  218. tyxml-syntax
  219. uri < "4.0.0"
  220. uri-re
  221. user-agent-parser
  222. user-setup
  223. uuuu < "0.4.0"
  224. validate
  225. vendredi
  226. wasm_of_ocaml-compiler
  227. wax-lib
  228. webmachine
  229. wire
  230. xtmpl >= "0.18.0"

Conflicts

None