package re

  1. Overview
  2. Docs
RE is a regular expression library for OCaml

Install

Dune Dependency

github.com Readme Changelog LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception License Edit opam file Versions (19)

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.

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. atd >= "2.2.1"
  6. atdcpp
  7. atdd
  8. atdgen >= "2.3.3"
  9. atdgen-runtime = "2.2.1"
  10. atdj >= "2.2.1"
  11. atdpy >= "2.4.1"
  12. atds < "2.3.3"
  13. atdts
  14. aws-config
  15. awsm-codegen
  16. BetterErrors
  17. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. benchpress
  25. bibfmt
  26. bio_io >= "0.5.1"
  27. biocaml
  28. bistro < "0.6.0"
  29. bonsai >= "v0.15.0"
  30. caisar >= "4.0"
  31. calculon
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. camlp5 >= "8.02.01"
  36. camlp5-buildscripts
  37. camyll
  38. caqti >= "1.7.0"
  39. catala
  40. chamo
  41. cinaps >= "v0.10.0"
  42. cohttp
  43. coin
  44. colibri2
  45. commons
  46. conan >= "0.0.6"
  47. core_bench
  48. core_extended
  49. cosovo
  50. cowabloga >= "0.4.0"
  51. crs
  52. cucumber
  53. cuid
  54. current
  55. current_web
  56. daypack-lib
  57. debian-formats
  58. decompress < "1.0.0"
  59. dkml-install-installer >= "0.4.0"
  60. dns < "4.4.1"
  61. doi2bib
  62. dose3
  63. dune-release >= "0.2.0"
  64. dunolint-lib
  65. duppy >= "0.9.4"
  66. elpi
  67. expect >= "0.1.0"
  68. expect_test_helpers_core
  69. expect_test_helpers_kernel
  70. ez_file
  71. ez_search
  72. fat-filesystem
  73. git-split < "1.0.0"
  74. gpiod
  75. graphql_parser >= "0.11.0"
  76. hardcaml_verify
  77. hardcaml_waveterm
  78. hardcaml_xilinx_components
  79. hlarp >= "0.0.3"
  80. horned_worm
  81. humane-re
  82. icalendar
  83. index
  84. index-bench
  85. irmin-bench
  86. jingoo >= "1.2.21"
  87. js_of_ocaml >= "3.10.0"
  88. js_of_ocaml-compiler >= "3.10.0"
  89. js_of_ocaml-lwt >= "3.10.0"
  90. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  91. js_of_ocaml-ppx >= "3.10.0"
  92. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  93. js_of_ocaml-toplevel >= "3.10.0"
  94. js_of_ocaml-tyxml >= "3.10.0"
  95. jsonschema
  96. jwt
  97. jwto
  98. kappa-library
  99. kubecaml
  100. labrys
  101. lastfm >= "0.3.4"
  102. ldap >= "2.5.1"
  103. learn-ocaml
  104. ledes
  105. lipsum
  106. liquidsoap >= "2.3.3"
  107. liquidsoap-core >= "2.3.0"
  108. liquidsoap-lang >= "2.3.0"
  109. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  110. MlFront_ZipFile
  111. magic-trace
  112. mdx
  113. mehari
  114. mparser-re
  115. naboris
  116. netsnmp
  117. ninja_utils
  118. nx-text
  119. obelisk >= "0.5.0"
  120. ocaml-lsp-server >= "1.9.0"
  121. ocamlformat >= "0.11.0"
  122. ocamlformat-mlx
  123. ocamlformat-rpc < "0.21.0"
  124. ocamlmig
  125. ocp-build
  126. ocp-index
  127. ocsigen-start
  128. ocsigenserver >= "5.1.0"
  129. octez-bls12-381-signature
  130. octez-libs
  131. opam-bin >= "0.9.5" & < "1.1.0"
  132. opam-client
  133. opam-compiler
  134. opam-core
  135. opam-format >= "2.0.8" & != "2.1.0~beta4"
  136. opam-lib
  137. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  138. opam-state >= "2.2.0"
  139. opam_bin_lib
  140. opium
  141. opium_kernel
  142. oranger
  143. orun
  144. ostap
  145. ozulip
  146. pa_ppx_parsetree
  147. pa_ppx_regexp >= "0.04"
  148. pa_ppx_string
  149. patdiff
  150. pgocaml >= "2.3"
  151. pgx
  152. plato
  153. podge >= "0.3"
  154. ppx_css < "v0.17.0"
  155. ppx_cstubs
  156. ppx_expect < "v0.17.0"
  157. ppx_expect_nobase
  158. ppx_minidebug >= "1.6.0"
  159. ppx_regexp >= "0.3.2"
  160. ppx_test
  161. ppx_tyre
  162. ppxlib >= "0.21.1"
  163. prometheus >= "0.2"
  164. prometheus-app
  165. pyml_bindgen >= "0.3.1"
  166. rdf >= "0.12.0"
  167. re_parser
  168. redis
  169. regenerate
  170. rfc1951 < "1.0.0"
  171. safemoney >= "0.3.0"
  172. sarek
  173. sarif >= "0.2.1"
  174. satyrographos >= "0.0.2.7"
  175. semantic_version
  176. sexp_pretty
  177. simple-diff
  178. slug
  179. snf_mcp
  180. soupault
  181. spoc
  182. statocaml_profile
  183. swagger
  184. testo
  185. testo-lwt
  186. testo-util
  187. tezos-clic >= "16.0"
  188. tezos-stdlib-unix
  189. tezt
  190. timere-parse
  191. touist >= "3.5.0"
  192. tyre >= "0.4"
  193. tyxml >= "4.2.0"
  194. tyxml-syntax
  195. uri < "4.0.0"
  196. uri-re
  197. user-agent-parser
  198. user-setup
  199. uuuu
  200. validate
  201. vendredi
  202. wasm_of_ocaml-compiler
  203. webmachine
  204. xtmpl >= "0.18.0"

Conflicts

None

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