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. benchpress
  25. bio_io >= "0.5.1"
  26. biocaml
  27. bistro < "0.6.0"
  28. bonsai >= "v0.15.0"
  29. calculon
  30. calculon-web
  31. caldav
  32. calendar >= "3.0.0"
  33. camlp5 >= "8.00.05"
  34. camlp5-buildscripts
  35. camyll
  36. caqti >= "1.7.0"
  37. catala
  38. chamo
  39. cinaps >= "v0.10.0"
  40. cohttp
  41. coin
  42. colibri2
  43. commons
  44. core_bench
  45. core_extended
  46. cosovo
  47. cowabloga >= "0.4.0"
  48. cucumber
  49. cuid
  50. current
  51. current_web >= "0.4"
  52. daypack-lib
  53. debian-formats
  54. decompress < "1.0.0"
  55. dkml-install-installer >= "0.4.0"
  56. dns < "4.0.0"
  57. doi2bib >= "0.5.1"
  58. dose3
  59. dune-release >= "0.2.0"
  60. dunolint-lib
  61. duppy >= "0.9.4"
  62. elpi
  63. expect >= "0.1.0"
  64. expect_test_helpers_core
  65. expect_test_helpers_kernel
  66. ez_file
  67. ez_search
  68. fat-filesystem
  69. git >= "1.9.0" & < "2.0.0"
  70. git-split < "1.0.0"
  71. gpiod
  72. graphql_parser >= "0.11.0"
  73. hardcaml_verify
  74. hardcaml_waveterm
  75. hardcaml_xilinx_components
  76. hlarp >= "0.0.3"
  77. horned_worm
  78. humane-re
  79. icalendar
  80. index
  81. index-bench
  82. irmin-bench >= "2.4.0"
  83. jingoo >= "1.2.21"
  84. js_of_ocaml >= "3.10.0"
  85. js_of_ocaml-compiler >= "3.10.0"
  86. js_of_ocaml-lwt >= "3.10.0"
  87. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  88. js_of_ocaml-ppx >= "3.10.0"
  89. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  90. js_of_ocaml-toplevel >= "3.10.0"
  91. js_of_ocaml-tyxml >= "3.10.0"
  92. jwt
  93. jwto
  94. kappa-library
  95. kubecaml
  96. labrys
  97. lastfm >= "0.3.4"
  98. ldap >= "2.5.1"
  99. learn-ocaml
  100. lipsum
  101. liquidsoap >= "2.3.1"
  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
  120. ocp-index
  121. ocsigen-start
  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
  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. opam_bin_lib
  135. opium
  136. opium_kernel
  137. oranger
  138. orun
  139. ostap
  140. ozulip
  141. pa_ppx_parsetree
  142. pa_ppx_regexp >= "0.04"
  143. pa_ppx_string
  144. patdiff
  145. pgocaml >= "2.3"
  146. pgx
  147. plato
  148. podge >= "0.3"
  149. ppx_css < "v0.17.0"
  150. ppx_cstubs
  151. ppx_expect < "v0.17.0"
  152. ppx_expect_nobase
  153. ppx_minidebug >= "1.0.0"
  154. ppx_regexp >= "0.3.2"
  155. ppx_test
  156. ppx_tyre
  157. ppxlib >= "0.21.0"
  158. prometheus >= "0.2"
  159. prometheus-app
  160. pyml_bindgen >= "0.3.1"
  161. rdf >= "0.12.0"
  162. re_parser
  163. redis
  164. regenerate
  165. rfc1951 < "1.0.0"
  166. sarek
  167. sarif >= "0.2.1"
  168. satyrographos >= "0.0.2.7"
  169. semantic_version
  170. sexp_pretty
  171. simple-diff
  172. slug
  173. soupault
  174. spoc
  175. swagger
  176. tar < "2.2.0"
  177. tar-mirage < "2.2.1"
  178. tar-unix < "2.2.0"
  179. testo
  180. testo-lwt
  181. testo-util
  182. tezos-clic >= "16.0"
  183. tezos-stdlib-unix
  184. tezt
  185. timere-parse
  186. touist >= "3.5.0"
  187. tyre >= "0.4"
  188. tyxml >= "4.2.0"
  189. tyxml-syntax
  190. uri < "4.0.0"
  191. uri-re
  192. user-agent-parser
  193. user-setup
  194. uuuu
  195. validate
  196. vendredi
  197. wasm_of_ocaml-compiler
  198. webmachine
  199. xtmpl >= "0.18.0"

Conflicts

None

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