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. ocp-build
  137. ocp-index
  138. ocsigen-start
  139. ocsigenserver >= "5.1.0"
  140. opam-bin >= "0.9.5" & < "1.1.0"
  141. opam-client
  142. opam-compiler
  143. opam-core
  144. opam-format >= "2.0.8" & != "2.1.0~beta4"
  145. opam-lib
  146. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  147. opam-state >= "2.2.0"
  148. opam_bin_lib
  149. opium
  150. opium_kernel
  151. oranger
  152. orun
  153. ostap
  154. ozulip
  155. pa_ppx_parsetree
  156. pa_ppx_regexp < "0.04"
  157. pa_ppx_string
  158. parseff
  159. patdiff
  160. pgocaml >= "2.3"
  161. pgx
  162. plato
  163. podge >= "0.3"
  164. ppx_css < "v0.17.0"
  165. ppx_cstubs
  166. ppx_expect < "v0.17.0"
  167. ppx_expect_nobase < "v0.17.3.0"
  168. ppx_mikmatch
  169. ppx_minidebug >= "1.6.0"
  170. ppx_regexp >= "0.3.2"
  171. ppx_test
  172. ppx_tyre
  173. ppxlib >= "0.21.1"
  174. prometheus >= "0.2"
  175. prometheus-app
  176. pyml_bindgen >= "0.3.1"
  177. raga
  178. rdf >= "0.12.0"
  179. re_parser
  180. redis
  181. regenerate
  182. regrade
  183. rfc1951 < "1.0.0"
  184. safemoney >= "0.3.0"
  185. saga
  186. sarek
  187. sarif >= "0.2.1"
  188. satyrographos >= "0.0.2.7"
  189. semantic_version
  190. sexp_pretty
  191. shakuhachi
  192. simple-diff
  193. slug
  194. smtml >= "0.21.0"
  195. snf_mcp
  196. soupault
  197. spectrum >= "0.7.0"
  198. spectrum_capabilities
  199. spectrum_palette_ppx
  200. spectrum_tools
  201. spoc
  202. swagger
  203. talon < "1.0.0~alpha3"
  204. testcontainers
  205. testo
  206. testo-lwt
  207. testo-util
  208. tezt
  209. timere-parse
  210. touist >= "3.5.0"
  211. tyre >= "0.4"
  212. tyxml >= "4.2.0"
  213. tyxml-syntax
  214. uri < "4.0.0"
  215. uri-re
  216. user-agent-parser
  217. user-setup
  218. uuuu < "0.4.0"
  219. validate
  220. vendredi
  221. wasm_of_ocaml-compiler
  222. webmachine
  223. xtmpl >= "0.18.0"

Conflicts

None