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. awso
  18. BetterErrors
  19. bancos
  20. bap-byteweight-frontend
  21. bap-callgraph-collator
  22. bap-fsi-benchmark
  23. bap-ida
  24. bap-objdump
  25. bap-print
  26. bap-radare2
  27. bibfmt
  28. bio_io >= "0.5.1"
  29. biocaml
  30. bonsai >= "v0.15.0"
  31. brot
  32. caisar < "4.0"
  33. calculon
  34. calculon-web
  35. caldav
  36. calendar >= "3.0.0"
  37. camlp5 >= "8.02.01"
  38. camlp5-buildscripts
  39. camyll
  40. caqti >= "1.7.0"
  41. cascade
  42. catala
  43. catala-format >= "1.2.0"
  44. chamo
  45. ciao_lwt
  46. cinaps
  47. cohttp
  48. coin < "0.1.5"
  49. colibri2
  50. commons
  51. conan = "0.0.5"
  52. core_bench
  53. core_extended
  54. cosovo
  55. cowabloga >= "0.4.0"
  56. cucumber
  57. cuid
  58. current
  59. current_web
  60. daypack-lib
  61. debian-formats
  62. decompress < "1.0.0"
  63. dns < "4.4.1"
  64. docfd >= "13.0.0"
  65. doi2bib
  66. dose3
  67. dune-glob >= "3.21.0"
  68. dune-release >= "0.2.0"
  69. dunolint >= "0.0.20251006"
  70. dunolint-lib
  71. dunolint-lib-base
  72. duppy >= "0.9.5"
  73. elpi
  74. expect_test_helpers_core
  75. expect_test_helpers_kernel
  76. ez_file
  77. ez_search
  78. fat-filesystem
  79. git-split < "1.0.0"
  80. gpiod
  81. graphql_parser >= "0.11.0"
  82. hardcaml_verify
  83. hardcaml_waveterm
  84. hardcaml_xilinx_components
  85. hlarp >= "0.0.3"
  86. humane-re
  87. icalendar
  88. index
  89. index-bench
  90. irmin-bench
  91. jingoo >= "1.2.21"
  92. js_of_ocaml >= "3.10.0"
  93. js_of_ocaml-compiler >= "3.10.0"
  94. js_of_ocaml-lwt >= "3.10.0"
  95. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  96. js_of_ocaml-ppx >= "3.10.0"
  97. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  98. js_of_ocaml-toplevel >= "3.10.0"
  99. js_of_ocaml-tyxml >= "3.10.0"
  100. jsonschema
  101. jsonschema-core
  102. jsonschema-validation
  103. jwt
  104. jwto
  105. kappa-agents >= "4.1.3"
  106. kappa-binaries >= "4.1.3"
  107. kappa-library
  108. kubecaml
  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_ppx_to_let_syntax
  118. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  119. MlFront_Core >= "2.4.2.30"
  120. MlFront_ZipFile
  121. magic-trace
  122. mdx
  123. mehari
  124. mnet-cli >= "0.0.3"
  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
  133. ocamlformat-mlx
  134. ocamlformat-rpc < "0.21.0"
  135. ocamlmig
  136. ocgtk < "0.1~preview2"
  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. playwright
  165. podge >= "0.3"
  166. ppx_css < "v0.17.0"
  167. ppx_cstubs
  168. ppx_expect < "v0.17.0"
  169. ppx_expect_nobase = "v0.17.2.2"
  170. ppx_mikmatch
  171. ppx_minidebug >= "1.6.0"
  172. ppx_regexp >= "0.3.2"
  173. ppx_test
  174. ppx_tyre
  175. ppxlib >= "0.21.1"
  176. prometheus >= "0.2"
  177. prometheus-app
  178. pyml_bindgen >= "0.3.1"
  179. raga
  180. rdf
  181. re_parser
  182. redis
  183. regrade
  184. rfc1951 < "1.0.0"
  185. safemoney >= "0.3.0"
  186. saga
  187. sarek
  188. sarif >= "0.2.1"
  189. satyrographos
  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. stem
  204. swagger
  205. talon < "1.0.0~alpha3"
  206. testcontainers
  207. testo
  208. testo-lwt
  209. testo-util
  210. tezt
  211. timere-parse
  212. touist >= "3.5.0"
  213. tw
  214. tyre >= "0.4"
  215. tyxml >= "4.2.0"
  216. tyxml-syntax
  217. uri < "4.0.0"
  218. uri-re
  219. user-agent-parser
  220. user-setup
  221. uuuu < "0.4.0"
  222. validate
  223. vendredi
  224. wasm_of_ocaml-compiler
  225. wax-lib
  226. webmachine
  227. wire
  228. xtmpl >= "0.18.0"

Conflicts

None