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. catala
  44. catala-format >= "1.2.0"
  45. chamo
  46. ciao_lwt
  47. cinaps
  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. docfd >= "13.0.0"
  67. doi2bib
  68. dose3
  69. dune-glob >= "3.21.0"
  70. dune-release >= "0.2.0"
  71. dunolint >= "0.0.20251006"
  72. dunolint-lib
  73. dunolint-lib-base
  74. duppy >= "0.9.5"
  75. elpi
  76. expect >= "0.1.0"
  77. expect_test_helpers_core
  78. expect_test_helpers_kernel
  79. ez_file
  80. ez_search
  81. fat-filesystem
  82. git-split < "1.0.0"
  83. gpiod
  84. graphql_parser >= "0.11.0"
  85. hardcaml_verify
  86. hardcaml_waveterm
  87. hardcaml_xilinx_components
  88. hlarp >= "0.0.3"
  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. lastfm >= "0.3.4"
  111. ldap >= "2.5.1"
  112. learn-ocaml
  113. ledes
  114. lipsum
  115. liquidsoap >= "2.3.3"
  116. liquidsoap-core >= "2.3.0"
  117. liquidsoap-lang >= "2.3.0"
  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. mnet-cli >= "0.0.3"
  126. mparser-re
  127. naboris
  128. netsnmp
  129. ninja_utils
  130. nx-text
  131. obelisk >= "0.5.0"
  132. ocaml-lsp-server >= "1.9.0"
  133. ocamlformat
  134. ocamlformat-mlx
  135. ocamlformat-rpc < "0.21.0"
  136. ocamlmig
  137. ocgtk
  138. ocp-build
  139. ocp-index
  140. ocsigen-start
  141. ocsigenserver >= "5.1.0"
  142. opam-bin >= "0.9.5" & < "1.1.0"
  143. opam-client
  144. opam-compiler
  145. opam-core
  146. opam-format >= "2.0.8" & != "2.1.0~beta4"
  147. opam-lib
  148. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  149. opam-state >= "2.2.0"
  150. opam_bin_lib
  151. opium
  152. opium_kernel
  153. oranger
  154. orun
  155. ostap
  156. ozulip
  157. pa_ppx_parsetree
  158. pa_ppx_regexp >= "0.04"
  159. pa_ppx_string
  160. parseff
  161. patdiff
  162. pgocaml >= "2.3"
  163. pgx
  164. plato
  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. statocaml_profile
  204. stem
  205. swagger
  206. talon < "1.0.0~alpha3"
  207. testcontainers
  208. testo
  209. testo-lwt
  210. testo-util
  211. tezt
  212. timere-parse
  213. touist >= "3.5.0"
  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. webmachine
  226. wire
  227. xtmpl >= "0.18.0"

Conflicts

None