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. BetterErrors
  20. bancos
  21. bap-byteweight-frontend
  22. bap-callgraph-collator
  23. bap-fsi-benchmark
  24. bap-ida
  25. bap-objdump
  26. bap-print
  27. bap-radare2
  28. bibfmt
  29. bio_io >= "0.5.1"
  30. biocaml
  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
  46. cohttp
  47. coin < "0.1.5"
  48. colibri2
  49. commons
  50. conan >= "0.0.6"
  51. core_bench
  52. core_extended
  53. cosovo
  54. cowabloga >= "0.4.0"
  55. crs
  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. doi2bib
  65. dose3
  66. dune-glob >= "3.21.0"
  67. dune-release >= "0.2.0"
  68. dunolint >= "0.0.20251006"
  69. dunolint-lib
  70. dunolint-lib-base
  71. duppy >= "0.9.5"
  72. elpi
  73. expect >= "0.1.0"
  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-library
  106. kubecaml
  107. lastfm >= "0.3.4"
  108. ldap >= "2.5.1"
  109. learn-ocaml
  110. ledes
  111. lipsum
  112. liquidsoap >= "2.3.3"
  113. liquidsoap-core >= "2.3.0"
  114. liquidsoap-lang >= "2.3.0"
  115. lwt_ppx_to_let_syntax
  116. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  117. MlFront_Core >= "2.4.2.30"
  118. MlFront_ZipFile
  119. magic-trace
  120. mdx
  121. mehari
  122. mparser-re
  123. naboris
  124. netsnmp
  125. ninja_utils
  126. nx-text
  127. obelisk >= "0.5.0"
  128. ocaml-lsp-server >= "1.9.0"
  129. ocamlformat
  130. ocamlformat-mlx
  131. ocamlformat-rpc < "0.21.0"
  132. ocamlmig
  133. ocgtk
  134. ocp-build
  135. ocp-index
  136. ocsigen-start
  137. ocsigenserver >= "5.1.0"
  138. opam-bin >= "0.9.5" & < "1.1.0"
  139. opam-client
  140. opam-compiler
  141. opam-core
  142. opam-format >= "2.0.8" & != "2.1.0~beta4"
  143. opam-lib
  144. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  145. opam-state >= "2.2.0"
  146. opam_bin_lib
  147. opium
  148. opium_kernel
  149. oranger
  150. orun
  151. ostap
  152. ozulip
  153. pa_ppx_parsetree
  154. pa_ppx_regexp >= "0.04"
  155. pa_ppx_string
  156. parseff
  157. patdiff
  158. pgocaml >= "2.3"
  159. pgx
  160. plato
  161. podge >= "0.3"
  162. ppx_css < "v0.17.0"
  163. ppx_cstubs
  164. ppx_expect < "v0.17.0"
  165. ppx_expect_nobase < "v0.17.3.0"
  166. ppx_mikmatch
  167. ppx_minidebug >= "1.6.0"
  168. ppx_regexp >= "0.3.2"
  169. ppx_test
  170. ppx_tyre
  171. ppxlib >= "0.21.1"
  172. prometheus >= "0.2"
  173. prometheus-app
  174. pyml_bindgen >= "0.3.1"
  175. raga
  176. rdf
  177. re_parser
  178. redis
  179. regrade
  180. rfc1951 < "1.0.0"
  181. safemoney >= "0.3.0"
  182. saga
  183. sarek
  184. sarif >= "0.2.1"
  185. satyrographos
  186. semantic_version
  187. sexp_pretty
  188. shakuhachi
  189. simple-diff
  190. slug
  191. smtml >= "0.21.0"
  192. snf_mcp
  193. soupault
  194. spectrum >= "0.7.0"
  195. spectrum_capabilities
  196. spectrum_palette_ppx
  197. spectrum_tools
  198. spoc
  199. statocaml_profile
  200. stem
  201. swagger
  202. talon < "1.0.0~alpha3"
  203. testcontainers
  204. testo
  205. testo-lwt
  206. testo-util
  207. tezt
  208. timere-parse
  209. touist >= "3.5.0"
  210. tyre >= "0.4"
  211. tyxml >= "4.2.0"
  212. tyxml-syntax
  213. uri < "4.0.0"
  214. uri-re
  215. user-agent-parser
  216. user-setup
  217. uuuu < "0.4.0"
  218. validate
  219. vendredi
  220. wasm_of_ocaml-compiler
  221. webmachine
  222. wire
  223. xtmpl >= "0.18.0"

Conflicts

None