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. atdcpp
  9. atdd
  10. atdgen >= "2.3.3"
  11. atdgen-runtime = "2.2.1"
  12. atdj >= "2.2.1"
  13. atdpy >= "2.4.1"
  14. atds < "2.3.3"
  15. atdts
  16. aws-config
  17. awsm-codegen
  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 >= "2.2.0"
  26. bap-radare2
  27. benchpress
  28. bibfmt
  29. bio_io >= "0.5.1"
  30. biocaml
  31. bistro < "0.6.0"
  32. bonsai >= "v0.15.0"
  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. cinaps >= "v0.10.0"
  45. cohttp
  46. coin < "0.1.5"
  47. colibri2
  48. commons
  49. conan >= "0.0.6"
  50. core_bench
  51. core_extended
  52. cosovo
  53. cowabloga >= "0.4.0"
  54. crs
  55. cucumber
  56. cuid
  57. current
  58. current_web
  59. daypack-lib
  60. debian-formats
  61. decompress < "1.0.0"
  62. dns < "4.4.1"
  63. doi2bib
  64. dose3
  65. dune-glob >= "3.21.0"
  66. dune-release >= "0.2.0"
  67. dunolint >= "0.0.20251006"
  68. dunolint-lib
  69. dunolint-lib-base
  70. duppy >= "0.9.5"
  71. elpi
  72. expect >= "0.1.0"
  73. expect_test_helpers_core
  74. expect_test_helpers_kernel
  75. ez_file
  76. ez_search
  77. fat-filesystem
  78. git-split < "1.0.0"
  79. gpiod
  80. graphql_parser >= "0.11.0"
  81. hardcaml_verify
  82. hardcaml_waveterm
  83. hardcaml_xilinx_components
  84. hlarp >= "0.0.3"
  85. horned_worm
  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. jwt
  102. jwto
  103. kappa-library
  104. kubecaml
  105. labrys
  106. lastfm >= "0.3.4"
  107. ldap >= "2.5.1"
  108. learn-ocaml
  109. ledes
  110. lipsum
  111. liquidsoap >= "2.3.3"
  112. liquidsoap-core >= "2.3.0"
  113. liquidsoap-lang >= "2.3.0"
  114. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  115. MlFront_Core >= "2.4.2.30"
  116. MlFront_ZipFile
  117. magic-trace
  118. mdx
  119. mehari
  120. mparser-re
  121. naboris
  122. netsnmp
  123. ninja_utils
  124. nx-text
  125. obelisk >= "0.5.0"
  126. ocaml-lsp-server >= "1.9.0"
  127. ocamlformat >= "0.11.0"
  128. ocamlformat-mlx
  129. ocamlformat-rpc < "0.21.0"
  130. ocamlmig
  131. ocp-build
  132. ocp-index
  133. ocsigen-start
  134. ocsigenserver >= "5.1.0"
  135. opam-bin >= "0.9.5" & < "1.1.0"
  136. opam-client
  137. opam-compiler
  138. opam-core
  139. opam-format >= "2.0.8" & != "2.1.0~beta4"
  140. opam-lib
  141. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  142. opam-state >= "2.2.0"
  143. opam_bin_lib
  144. opium
  145. opium_kernel
  146. oranger
  147. orun
  148. ostap
  149. ozulip
  150. pa_ppx_parsetree
  151. pa_ppx_regexp >= "0.04"
  152. pa_ppx_string
  153. patdiff
  154. pgocaml >= "2.3"
  155. pgx
  156. plato
  157. podge >= "0.3"
  158. ppx_css < "v0.17.0"
  159. ppx_cstubs
  160. ppx_expect < "v0.17.0"
  161. ppx_expect_nobase < "v0.17.3.0"
  162. ppx_minidebug >= "1.6.0"
  163. ppx_regexp >= "0.3.2"
  164. ppx_test
  165. ppx_tyre
  166. ppxlib >= "0.21.1"
  167. prometheus >= "0.2"
  168. prometheus-app
  169. pyml_bindgen >= "0.3.1"
  170. raga
  171. rdf >= "0.12.0"
  172. re_parser
  173. redis
  174. regenerate
  175. regrade
  176. rfc1951 < "1.0.0"
  177. safemoney >= "0.3.0"
  178. saga
  179. sarek
  180. sarif >= "0.2.1"
  181. satyrographos >= "0.0.2.7"
  182. semantic_version
  183. sexp_pretty
  184. shakuhachi
  185. simple-diff
  186. slug
  187. smtml >= "0.21.0"
  188. snf_mcp
  189. soupault
  190. spoc
  191. statocaml_profile
  192. swagger
  193. talon
  194. testo
  195. testo-lwt
  196. testo-util
  197. tezt
  198. timere-parse
  199. touist >= "3.5.0"
  200. tyre >= "0.4"
  201. tyxml >= "4.2.0"
  202. tyxml-syntax
  203. uri < "4.0.0"
  204. uri-re
  205. user-agent-parser
  206. user-setup
  207. uuuu < "0.4.0"
  208. validate
  209. vendredi
  210. wasm_of_ocaml-compiler
  211. webmachine
  212. xtmpl >= "0.18.0"

Conflicts

None