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. doi2bib
  67. dose3
  68. dune-glob >= "3.21.0"
  69. dune-release >= "0.2.0"
  70. dunolint >= "0.0.20251006"
  71. dunolint-lib
  72. dunolint-lib-base
  73. duppy >= "0.9.5"
  74. elpi
  75. expect >= "0.1.0"
  76. expect_test_helpers_core
  77. expect_test_helpers_kernel
  78. ez_file
  79. ez_search
  80. fat-filesystem
  81. git-split < "1.0.0"
  82. gpiod
  83. graphql_parser >= "0.11.0"
  84. hardcaml_verify
  85. hardcaml_waveterm
  86. hardcaml_xilinx_components
  87. hlarp >= "0.0.3"
  88. humane-re
  89. icalendar
  90. index
  91. index-bench
  92. irmin-bench
  93. jingoo >= "1.2.21"
  94. js_of_ocaml >= "3.10.0"
  95. js_of_ocaml-compiler >= "3.10.0"
  96. js_of_ocaml-lwt >= "3.10.0"
  97. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  98. js_of_ocaml-ppx >= "3.10.0"
  99. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  100. js_of_ocaml-toplevel >= "3.10.0"
  101. js_of_ocaml-tyxml >= "3.10.0"
  102. jsonschema
  103. jsonschema-core
  104. jsonschema-validation
  105. jwt
  106. jwto
  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. mparser-re
  125. naboris
  126. netsnmp
  127. ninja_utils
  128. nx-text
  129. obelisk >= "0.5.0"
  130. ocaml-lsp-server >= "1.9.0"
  131. ocamlformat
  132. ocamlformat-mlx
  133. ocamlformat-rpc < "0.21.0"
  134. ocamlmig
  135. ocgtk
  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
  179. re_parser
  180. redis
  181. regrade
  182. rfc1951 < "1.0.0"
  183. safemoney >= "0.3.0"
  184. saga
  185. sarek
  186. sarif >= "0.2.1"
  187. satyrographos
  188. semantic_version
  189. sexp_pretty
  190. shakuhachi
  191. simple-diff
  192. slug
  193. smtml >= "0.21.0"
  194. snf_mcp
  195. soupault
  196. spectrum >= "0.7.0"
  197. spectrum_capabilities
  198. spectrum_palette_ppx
  199. spectrum_tools
  200. spoc
  201. statocaml_profile
  202. stem
  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