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)

Added to opam-repository:

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. hegel >= "0.24.1"
  90. hlarp >= "0.0.3"
  91. humane-re
  92. icalendar
  93. index
  94. index-bench
  95. irmin-bench
  96. jingoo >= "1.2.21"
  97. js_of_ocaml >= "3.10.0"
  98. js_of_ocaml-compiler >= "3.10.0"
  99. js_of_ocaml-lwt >= "3.10.0"
  100. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  101. js_of_ocaml-ppx >= "3.10.0"
  102. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  103. js_of_ocaml-toplevel >= "3.10.0"
  104. js_of_ocaml-tyxml >= "3.10.0"
  105. jsonschema
  106. jsonschema-core
  107. jsonschema-validation
  108. jwt
  109. jwto
  110. kappa-library
  111. kubecaml
  112. lastfm >= "0.3.4"
  113. ldap >= "2.5.1"
  114. learn-ocaml
  115. ledes
  116. lipsum
  117. liquidsoap >= "2.3.3"
  118. liquidsoap-core >= "2.3.0"
  119. liquidsoap-lang >= "2.3.0"
  120. lwt_ppx_to_let_syntax
  121. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  122. MlFront_Core >= "2.4.2.30"
  123. MlFront_ZipFile
  124. magic-trace
  125. mdx
  126. mehari
  127. mnet-cli >= "0.0.3" & < "0.0.8"
  128. mparser-re
  129. naboris
  130. netsnmp
  131. ninja_utils
  132. nx-text
  133. obelisk >= "0.5.0"
  134. ocaml-lsp-server >= "1.9.0"
  135. ocamlformat
  136. ocamlformat-mlx
  137. ocamlformat-rpc < "0.21.0"
  138. ocamlmig
  139. ocgtk < "0.1~preview2"
  140. ocp-build
  141. ocp-index
  142. ocsigen-start
  143. ocsigenserver >= "5.1.0"
  144. opam-bin >= "0.9.5" & < "1.1.0"
  145. opam-client < "2.6.0~alpha1"
  146. opam-compiler
  147. opam-core
  148. opam-format >= "2.0.8" & != "2.1.0~beta4" & < "2.6.0~alpha1"
  149. opam-lib
  150. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0" & < "2.6.0~alpha1"
  151. opam-state >= "2.2.0" & < "2.6.0~alpha1"
  152. opam_bin_lib
  153. opium
  154. opium_kernel
  155. oranger
  156. orun
  157. ostap
  158. oxbow
  159. ozulip
  160. pa_ppx_parsetree
  161. pa_ppx_regexp >= "0.04"
  162. pa_ppx_string
  163. parseff
  164. patdiff
  165. pgocaml >= "2.3"
  166. pgx
  167. plato
  168. playwright
  169. podge >= "0.3"
  170. ppx_css < "v0.17.0"
  171. ppx_cstubs
  172. ppx_elpi
  173. ppx_expect < "v0.17.0"
  174. ppx_expect_nobase = "v0.17.2.2"
  175. ppx_mikmatch
  176. ppx_minidebug >= "1.6.0"
  177. ppx_regexp >= "0.3.2"
  178. ppx_test
  179. ppx_tyre
  180. ppxlib >= "0.21.1"
  181. prometheus >= "0.2"
  182. prometheus-app < "2.0"
  183. prometheus-reporter
  184. pyml_bindgen >= "0.3.1"
  185. raga
  186. rdf
  187. re_parser
  188. redis
  189. regrade
  190. rfc1951 < "1.0.0"
  191. safemoney >= "0.3.0"
  192. saga
  193. sarek
  194. sarif >= "0.2.1"
  195. satyrographos
  196. semantic_version
  197. sexp_pretty
  198. shakuhachi
  199. simple-diff
  200. slug
  201. smtml >= "0.21.0"
  202. snf_mcp
  203. sosie
  204. soupault
  205. spectrum >= "0.7.0"
  206. spectrum_capabilities
  207. spectrum_palette_ppx
  208. spectrum_tools
  209. spoc
  210. statocaml_profile
  211. stem
  212. swagger
  213. talon < "1.0.0~alpha3"
  214. testcontainers
  215. testo
  216. testo-lwt
  217. testo-util
  218. tezt
  219. timere-parse
  220. touist >= "3.5.0"
  221. tw < "1.1.0"
  222. tyre >= "0.4"
  223. tyxml >= "4.2.0"
  224. tyxml-ppx >= "5.0.0"
  225. tyxml-syntax
  226. unic
  227. uri < "4.0.0"
  228. uri-re
  229. user-agent-parser
  230. user-setup
  231. uuuu < "0.4.0"
  232. validate
  233. vendredi
  234. wasm_of_ocaml-compiler
  235. wax-lib
  236. webmachine
  237. wire
  238. xtmpl >= "0.18.0"

Conflicts

None