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-1.11.0.tbz
sha256=01fc244780c0f6be72ae796b1fb750f367de18624fd75d07ee79782ed6df8d4f
sha512=3e3712cc1266ec1f27620f3508ea2ebba338f4083b07d8a69dccee1facfdc1971a6c39f9deea664d2a62fd7f2cfd2eae816ca4c274acfadaee992a3befc4b757

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: 23 Aug 2023

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 >= "4.03"

Dev Dependencies (1)

  1. ounit with-test

  1. alcotest
  2. alcotest-async
  3. alcotest-lwt
  4. alcotest-mirage
  5. atd >= "2.2.1"
  6. atd-jsonlike
  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. bancos
  19. bap-byteweight-frontend
  20. bap-callgraph-collator
  21. bap-fsi-benchmark
  22. bap-ida
  23. bap-objdump
  24. bap-print >= "2.2.0"
  25. bap-radare2
  26. benchpress
  27. bibfmt
  28. bio_io >= "0.5.1"
  29. biocaml
  30. bistro < "0.6.0"
  31. bonsai >= "v0.15.0"
  32. brot
  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. ciao_lwt
  45. cinaps >= "v0.10.0"
  46. cohttp
  47. coin < "0.1.5"
  48. colibri2
  49. commons
  50. conan = "0.0.5"
  51. core_bench
  52. core_extended
  53. cosovo
  54. cowabloga >= "0.4.0"
  55. cucumber
  56. cuid
  57. current
  58. current_web
  59. daypack-lib
  60. debian-formats
  61. decompress < "1.0.0"
  62. dns < "4.4.1"
  63. doi2bib
  64. dose3
  65. dune-glob >= "3.21.0"
  66. dune-release >= "0.2.0"
  67. dunolint >= "0.0.20251006"
  68. dunolint-lib
  69. dunolint-lib-base
  70. duppy >= "0.9.5"
  71. elpi
  72. expect_test_helpers_core
  73. expect_test_helpers_kernel
  74. ez_file
  75. ez_search
  76. fat-filesystem
  77. git-split < "1.0.0"
  78. gpiod
  79. graphql_parser >= "0.11.0"
  80. hardcaml_verify
  81. hardcaml_waveterm
  82. hardcaml_xilinx_components
  83. hlarp >= "0.0.3"
  84. horned_worm
  85. humane-re
  86. icalendar
  87. index
  88. index-bench
  89. irmin-bench
  90. jingoo >= "1.2.21"
  91. js_of_ocaml >= "3.10.0"
  92. js_of_ocaml-compiler >= "3.10.0"
  93. js_of_ocaml-lwt >= "3.10.0"
  94. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  95. js_of_ocaml-ppx >= "3.10.0"
  96. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  97. js_of_ocaml-toplevel >= "3.10.0"
  98. js_of_ocaml-tyxml >= "3.10.0"
  99. jsonschema
  100. jsonschema-core
  101. jsonschema-validation
  102. jwt
  103. jwto
  104. kappa-agents >= "4.1.3"
  105. kappa-binaries >= "4.1.3"
  106. kappa-library
  107. kubecaml
  108. labrys
  109. lastfm >= "0.3.4"
  110. ldap >= "2.5.1"
  111. learn-ocaml
  112. ledes
  113. lipsum
  114. liquidsoap >= "2.3.3"
  115. liquidsoap-core >= "2.3.0"
  116. liquidsoap-lang >= "2.3.0"
  117. lwt_lint
  118. lwt_ppx_to_let_syntax
  119. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  120. MlFront_Core >= "2.4.2.30"
  121. MlFront_ZipFile
  122. magic-trace
  123. mdx
  124. mehari
  125. mparser-re
  126. naboris
  127. netsnmp
  128. ninja_utils
  129. nx-text
  130. obelisk >= "0.5.0"
  131. ocaml-lsp-server >= "1.9.0"
  132. ocamlformat >= "0.11.0"
  133. ocamlformat-mlx
  134. ocamlformat-rpc < "0.21.0"
  135. ocamlmig
  136. ocgtk
  137. ocp-build
  138. ocp-index
  139. ocsigen-start
  140. ocsigenserver >= "5.1.0"
  141. opam-bin >= "0.9.5" & < "1.1.0"
  142. opam-client
  143. opam-compiler
  144. opam-core
  145. opam-format >= "2.0.8" & != "2.1.0~beta4"
  146. opam-lib
  147. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  148. opam-state >= "2.2.0"
  149. opam_bin_lib
  150. opium
  151. opium_kernel
  152. oranger
  153. orun
  154. ostap
  155. ozulip
  156. pa_ppx_parsetree
  157. pa_ppx_regexp < "0.04"
  158. pa_ppx_string
  159. parseff
  160. patdiff
  161. pgocaml >= "2.3"
  162. pgx
  163. plato
  164. podge >= "0.3"
  165. ppx_css < "v0.17.0"
  166. ppx_cstubs
  167. ppx_expect < "v0.17.0"
  168. ppx_expect_nobase < "v0.17.3.0"
  169. ppx_mikmatch
  170. ppx_minidebug >= "1.6.0"
  171. ppx_regexp >= "0.3.2"
  172. ppx_test
  173. ppx_tyre
  174. ppxlib >= "0.21.1"
  175. prometheus >= "0.2"
  176. prometheus-app
  177. pyml_bindgen >= "0.3.1"
  178. raga
  179. rdf >= "0.12.0"
  180. re_parser
  181. redis
  182. regenerate
  183. regrade
  184. rfc1951 < "1.0.0"
  185. safemoney >= "0.3.0"
  186. saga
  187. sarek
  188. sarif >= "0.2.1"
  189. satyrographos >= "0.0.2.7"
  190. semantic_version
  191. sexp_pretty
  192. shakuhachi
  193. simple-diff
  194. slug
  195. smtml >= "0.21.0"
  196. snf_mcp
  197. soupault
  198. spectrum >= "0.7.0"
  199. spectrum_capabilities
  200. spectrum_palette_ppx
  201. spectrum_tools
  202. spoc
  203. swagger
  204. talon < "1.0.0~alpha3"
  205. testcontainers
  206. testo
  207. testo-lwt
  208. testo-util
  209. tezt
  210. timere-parse
  211. touist >= "3.5.0"
  212. tyre >= "0.4"
  213. tyxml >= "4.2.0"
  214. tyxml-syntax
  215. uri < "4.0.0"
  216. uri-re
  217. user-agent-parser
  218. user-setup
  219. uuuu < "0.4.0"
  220. validate
  221. vendredi
  222. wasm_of_ocaml-compiler
  223. webmachine
  224. wire
  225. xtmpl >= "0.18.0"

Conflicts

None