package re

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

Install

Dune Dependency

github.com Readme Changelog LGPL-2.0 with OCaml linking exception License Edit opam file Versions (22)

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-1.10.3.tbz
sha256=846546967f3fe31765935dd40a6460a9424337ecce7b12727fcba49480790ebb
sha512=d02103b7b8b8d8bc797341dcc933554745427f3c1b51b54b4ac9ff81badfd68c94726c57548b08e00ca99f3e09741b54b6500e97c19fc0e8fcefd6dfbe71da7f

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: 17 Sep 2021

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 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 >= "4.02"

Dev Dependencies (1)

  1. ounit with-test

  1. alcotest < "0.4.3" | >= "1.0.0"
  2. alcotest-async >= "1.3.0"
  3. alcotest-lwt >= "1.3.0"
  4. alcotest-mirage >= "1.3.0"
  5. atd >= "2.2.1"
  6. atdd
  7. atdgen >= "2.3.3"
  8. atdgen-runtime = "2.2.1"
  9. atdj >= "2.2.1" & < "20151001.01"
  10. atdpy >= "2.4.1"
  11. atds < "2.3.3"
  12. atdts
  13. aws-config
  14. awsm-codegen
  15. BetterErrors
  16. bap < "1.0.0"
  17. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump < "1.4.0" | >= "1.6.0"
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. bap-server
  25. benchpress
  26. bio_io >= "0.5.1"
  27. biocaml = "0.4.0" | >= "0.8.0"
  28. bistro = "0.5.0"
  29. bonsai >= "v0.15.0"
  30. bulletml
  31. calculon >= "0.2"
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. camlp5 >= "8.00.05" & < "8.02.01"
  36. camyll
  37. caqti >= "1.7.0"
  38. catala
  39. ccss >= "1.6"
  40. cinaps >= "v0.10.0"
  41. cohttp
  42. coin
  43. colibri2
  44. conan < "0.0.5"
  45. core_bench >= "v0.9.0"
  46. core_extended >= "v0.10.0"
  47. cosovo
  48. cow < "1.2.2"
  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. dns < "4.0.0"
  58. dog < "0.2.1"
  59. doi2bib >= "0.5.1"
  60. dose
  61. dose3
  62. dune-release >= "0.2.0"
  63. duppy >= "0.9.4"
  64. elpi
  65. expect_test_helpers_core
  66. expect_test_helpers_kernel
  67. ez_file
  68. ez_search
  69. fat-filesystem != "0.12.0"
  70. frag
  71. gensqlite
  72. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  73. gpiod
  74. graphql_parser >= "0.11.0"
  75. hardcaml_verify
  76. hardcaml_waveterm
  77. hardcaml_xilinx_components
  78. hlarp >= "0.0.3"
  79. horned_worm
  80. http_router
  81. humane-re
  82. icalendar
  83. imaplet-lwt >= "0.1.9"
  84. index
  85. index-bench
  86. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  87. irmin-bench >= "2.4.0"
  88. iso-filesystem
  89. jingoo >= "1.2.21"
  90. js_of_ocaml >= "3.10.0"
  91. js_of_ocaml-compiler >= "3.10.0"
  92. js_of_ocaml-lwt >= "3.10.0"
  93. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  94. js_of_ocaml-ppx >= "3.10.0"
  95. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  96. js_of_ocaml-toplevel >= "3.10.0"
  97. js_of_ocaml-tyxml >= "3.10.0"
  98. jwt
  99. jwto
  100. kappa-library
  101. kubecaml
  102. labrys
  103. learn-ocaml >= "0.13.0"
  104. libres3 >= "0.3"
  105. lipsum
  106. magic-trace
  107. mbr-format < "1.0.0"
  108. mdx
  109. message-switch
  110. mirage >= "0.10.0" & < "2.4.0"
  111. mirage-bootvar-xen < "0.3.2"
  112. mirage-www < "1.0.0"
  113. mparser-re
  114. mustache < "2.0.0"
  115. naboris
  116. netsnmp
  117. ninja_utils
  118. obelisk >= "0.5.0"
  119. ocaml-lsp-server >= "1.7.0"
  120. ocamlformat >= "0.11.0"
  121. ocamlformat-rpc < "0.21.0"
  122. ocp-build >= "1.99.21"
  123. ocp-index >= "1.0.2"
  124. ocsigen-start >= "1.7.0"
  125. octez-bls12-381-signature
  126. octez-libs
  127. odoc >= "2.0.0" & < "2.1.0"
  128. opam-bin >= "0.9.5" & < "1.1.0"
  129. opam-build-revdeps
  130. opam-client >= "2.0.0~rc2"
  131. opam-compiler
  132. opam-core
  133. opam-format >= "2.0.8" & < "2.1.0~beta2" | >= "2.1.0~rc"
  134. opam-lib
  135. opam-solver >= "2.0.8" & < "2.1.0~beta2" | >= "2.2.0~alpha"
  136. opam-state >= "2.2.0~alpha"
  137. opam2web >= "1.3.0"
  138. opam_bin_lib
  139. operf-macro
  140. opium >= "0.13.1"
  141. opium_kernel
  142. oranger
  143. orun
  144. ostap
  145. ozulip
  146. pa_ppx_regexp < "0.02"
  147. patdiff >= "v0.12.0"
  148. pgocaml >= "2.3"
  149. pgx
  150. plato
  151. podge >= "0.3"
  152. ppx_css
  153. ppx_cstubs
  154. ppx_expect >= "113.33.00"
  155. ppx_implicits >= "0.1.0"
  156. ppx_minidebug >= "1.0.0"
  157. ppx_orakuda >= "3.0.0"
  158. ppx_regexp >= "0.3.2"
  159. ppx_sqlexpr
  160. ppx_test >= "1.1.0"
  161. ppx_tyre
  162. ppxlib >= "0.21.0"
  163. prometheus >= "0.2"
  164. prometheus-app >= "0.2"
  165. pyml_bindgen >= "0.3.1"
  166. rdf >= "0.12.0" & < "1.0.0"
  167. re_parser
  168. reason < "1.7.4"
  169. receive-mail
  170. redis >= "0.2.1"
  171. regenerate
  172. rfc1951 < "1.0.0"
  173. sarek >= "20210823"
  174. sarif >= "0.2.1"
  175. satyrographos >= "0.0.2.7"
  176. semantic_version
  177. sexp_pretty
  178. sill >= "1.3.1"
  179. simple-diff
  180. slug
  181. soupault
  182. spoc >= "20210823"
  183. sqlexpr >= "0.7.1" & < "0.9.0"
  184. swagger
  185. tar < "2.2.0"
  186. tar-format >= "0.2.0"
  187. tar-mirage < "2.2.0"
  188. tar-unix < "2.2.0"
  189. testrunner
  190. tezos-base < "7.4"
  191. tezos-clic < "8.0" | >= "13.0"
  192. tezos-protocol-compiler = "10.2" | = "13.0"
  193. tezos-stdlib-unix >= "7.4"
  194. tezt
  195. timere-parse
  196. touist >= "3.5.0"
  197. tyre >= "0.4"
  198. tyxml >= "4.0.0"
  199. tyxml-syntax
  200. uri < "4.0.0"
  201. uri-re
  202. user-agent-parser
  203. user-setup
  204. uuuu
  205. validate
  206. vendredi
  207. vhd-tool >= "0.12.0"
  208. webmachine
  209. xapi-idl
  210. xe
  211. xen-api-client >= "0.9.6"
  212. xtmpl >= "0.15.0"

Conflicts

None