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 (18)

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 >= "1.3.0"
  3. alcotest-lwt >= "1.3.0"
  4. alcotest-mirage >= "1.3.0"
  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. bap-server
  25. benchpress
  26. bio_io >= "0.5.1"
  27. biocaml
  28. bistro = "0.5.0"
  29. bonsai >= "v0.15.0"
  30. calculon
  31. calculon-web
  32. caldav
  33. calendar >= "3.0.0"
  34. camlp5 >= "8.00.05"
  35. camlp5-buildscripts
  36. camyll
  37. caqti >= "1.7.0"
  38. catala
  39. ccss
  40. chamo
  41. cinaps >= "v0.10.0"
  42. cohttp
  43. coin
  44. colibri2
  45. commons
  46. core_bench
  47. core_extended
  48. cosovo
  49. cowabloga >= "0.4.0"
  50. cucumber
  51. cuid
  52. current
  53. current_web >= "0.4"
  54. daypack-lib
  55. debian-formats
  56. decompress >= "0.8" & < "1.0.0"
  57. dkml-install-installer >= "0.4.0"
  58. dns < "4.0.0"
  59. doi2bib >= "0.5.1"
  60. dose3
  61. dune-release >= "0.2.0"
  62. duppy >= "0.9.4"
  63. elpi
  64. expect >= "0.1.0"
  65. expect_test_helpers_core
  66. expect_test_helpers_kernel
  67. ez_file
  68. ez_search
  69. fat-filesystem
  70. git >= "1.9.0" & < "1.10.0"
  71. git-split < "1.0.0"
  72. gpiod
  73. graphql_parser >= "0.11.0"
  74. hardcaml_verify
  75. hardcaml_waveterm
  76. hardcaml_xilinx_components
  77. hlarp >= "0.0.3"
  78. horned_worm
  79. humane-re
  80. icalendar
  81. index
  82. index-bench
  83. irmin-bench >= "2.4.0"
  84. jingoo >= "1.2.21"
  85. js_of_ocaml >= "3.10.0"
  86. js_of_ocaml-compiler >= "3.10.0"
  87. js_of_ocaml-lwt >= "3.10.0"
  88. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  89. js_of_ocaml-ppx >= "3.10.0"
  90. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  91. js_of_ocaml-toplevel >= "3.10.0"
  92. js_of_ocaml-tyxml >= "3.10.0"
  93. jwt
  94. jwto
  95. kappa-library
  96. kubecaml
  97. labrys
  98. lastfm >= "0.3.4"
  99. ldap >= "2.5.1"
  100. learn-ocaml
  101. lipsum
  102. liquidsoap-core >= "2.3.0"
  103. liquidsoap-lang >= "2.3.0"
  104. MlFront_Cli >= "2.1.4~prerel2"
  105. magic-trace
  106. mdx
  107. mehari
  108. mirage-bootvar-xen < "0.3.2"
  109. mparser-re
  110. naboris
  111. netsnmp
  112. ninja_utils
  113. obelisk >= "0.5.0"
  114. ocaml-lsp-server >= "1.7.0"
  115. ocamlformat >= "0.11.0"
  116. ocamlformat-mlx
  117. ocamlformat-rpc < "0.21.0"
  118. ocamlmig
  119. ocp-build >= "1.99.21"
  120. ocp-index
  121. ocsigen-start >= "1.7.0"
  122. ocsigenserver >= "5.1.0"
  123. octez-bls12-381-signature
  124. octez-libs
  125. odoc >= "2.0.0" & < "2.1.0"
  126. opam-bin >= "0.9.5" & < "1.1.0"
  127. opam-client >= "2.0.0~rc2"
  128. opam-compiler
  129. opam-core
  130. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  131. opam-lib
  132. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  133. opam-state >= "2.2.0~alpha"
  134. opam2web
  135. opam_bin_lib
  136. opium
  137. opium_kernel
  138. oranger
  139. orun
  140. ostap
  141. ozulip
  142. pa_ppx_parsetree
  143. pa_ppx_regexp >= "0.04"
  144. pa_ppx_string
  145. patdiff >= "v0.12.0"
  146. pgocaml >= "2.3"
  147. pgx
  148. plato
  149. podge >= "0.3"
  150. ppx_css < "v0.17.0"
  151. ppx_cstubs
  152. ppx_expect < "v0.17.0"
  153. ppx_expect_nobase
  154. ppx_minidebug >= "1.0.0"
  155. ppx_orakuda
  156. ppx_regexp >= "0.3.2"
  157. ppx_sqlexpr
  158. ppx_test
  159. ppx_tyre
  160. ppxlib >= "0.21.0"
  161. prometheus >= "0.2"
  162. prometheus-app
  163. pyml_bindgen >= "0.3.1"
  164. rdf >= "0.12.0"
  165. re_parser
  166. redis
  167. regenerate
  168. rfc1951 < "1.0.0"
  169. sarek
  170. sarif >= "0.2.1"
  171. satyrographos >= "0.0.2.7"
  172. semantic_version
  173. sexp_pretty
  174. simple-diff
  175. slug
  176. soupault
  177. spoc >= "20210823"
  178. swagger
  179. tar < "2.2.0"
  180. tar-mirage < "2.2.1"
  181. tar-unix < "2.2.0"
  182. testo
  183. testo-lwt
  184. testo-util
  185. testrunner
  186. tezos-clic >= "16.0"
  187. tezos-stdlib-unix
  188. tezt
  189. timere-parse
  190. touist >= "3.5.0"
  191. tyre >= "0.4"
  192. tyxml >= "4.2.0"
  193. tyxml-syntax
  194. uri < "4.0.0"
  195. uri-re
  196. user-agent-parser
  197. user-setup
  198. uuuu
  199. validate
  200. vendredi
  201. webmachine
  202. xtmpl >= "0.17.0"

Conflicts

None

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