package re

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

Install

Dune Dependency

github.com Readme Changelog LGPL-2.0-only WITH OCaml-LGPL-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-1.9.0.tbz
md5=bddaed4f386a22cace7850c9c7dac296

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: 06 Apr 2019

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
  3. ocaml >= "4.08"

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. biocaml = "0.4.0" | >= "0.8.0"
  27. bistro = "0.5.0"
  28. bonsai >= "v0.15.0"
  29. bulletml
  30. calculon >= "0.2"
  31. calculon-web
  32. caldav
  33. calendar >= "3.0.0"
  34. camlp5 >= "8.00.05" & < "8.02.01"
  35. camyll
  36. caqti >= "1.7.0"
  37. catala != "0.8.0"
  38. ccss >= "1.6"
  39. cinaps >= "v0.10.0"
  40. cohttp
  41. coin
  42. conan < "0.0.5"
  43. core_bench >= "v0.9.0"
  44. core_extended >= "v0.10.0"
  45. cosovo
  46. cow < "1.2.2"
  47. cowabloga >= "0.4.0"
  48. cucumber
  49. cuid
  50. current
  51. current_web >= "0.4"
  52. daypack-lib
  53. debian-formats
  54. decompress >= "0.8" & < "1.0.0"
  55. dns < "4.0.0"
  56. dog < "0.2.1"
  57. doi2bib >= "0.5.1"
  58. dose
  59. dose3
  60. dune-release >= "0.2.0"
  61. duppy >= "0.9.4"
  62. elpi
  63. expect_test_helpers_core
  64. expect_test_helpers_kernel
  65. ez_file
  66. ez_search
  67. fat-filesystem != "0.12.0"
  68. frag
  69. gensqlite
  70. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  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. http_router
  79. humane-re
  80. icalendar
  81. imaplet-lwt >= "0.1.9"
  82. index
  83. index-bench
  84. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  85. irmin-bench >= "2.4.0"
  86. iso-filesystem
  87. jingoo >= "1.2.21"
  88. js_of_ocaml >= "3.10.0"
  89. js_of_ocaml-compiler >= "3.10.0"
  90. js_of_ocaml-lwt >= "3.10.0"
  91. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  92. js_of_ocaml-ppx >= "3.10.0"
  93. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  94. js_of_ocaml-toplevel >= "3.10.0"
  95. js_of_ocaml-tyxml >= "3.10.0"
  96. jwt
  97. jwto
  98. kappa-library
  99. kubecaml
  100. labrys
  101. learn-ocaml >= "0.13.0"
  102. libres3 >= "0.3"
  103. lipsum
  104. magic-trace
  105. mbr-format < "1.0.0"
  106. mdx
  107. message-switch
  108. mirage >= "0.10.0" & < "2.4.0"
  109. mirage-bootvar-xen < "0.3.2"
  110. mirage-www < "1.0.0"
  111. mparser-re
  112. mustache < "2.0.0"
  113. naboris
  114. netsnmp
  115. obelisk >= "0.5.0"
  116. ocaml-lsp-server >= "1.7.0"
  117. ocamlformat >= "0.11.0" & < "0.25.1"
  118. ocamlformat-rpc < "0.21.0"
  119. ocp-build >= "1.99.21"
  120. ocp-index >= "1.0.2"
  121. ocsigen-start >= "1.7.0"
  122. octez-bls12-381-signature
  123. octez-libs < "19.0"
  124. odoc >= "2.0.0" & < "2.1.0"
  125. opam-bin >= "0.9.5" & < "1.1.0"
  126. opam-build-revdeps
  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 >= "1.3.0"
  135. opam_bin_lib
  136. operf-macro
  137. opium >= "0.13.1"
  138. opium_kernel
  139. oranger
  140. orun
  141. ostap
  142. ozulip
  143. pa_ppx_regexp < "0.02"
  144. patdiff >= "v0.12.0"
  145. pgocaml >= "2.3"
  146. pgx
  147. plato
  148. podge >= "0.3"
  149. ppx_css
  150. ppx_cstubs
  151. ppx_expect >= "113.33.00"
  152. ppx_implicits >= "0.1.0"
  153. ppx_minidebug >= "1.0.0"
  154. ppx_orakuda >= "3.0.0"
  155. ppx_regexp >= "0.3.2"
  156. ppx_sqlexpr
  157. ppx_test >= "1.1.0"
  158. ppx_tyre
  159. ppxlib >= "0.21.0"
  160. prometheus >= "0.2"
  161. prometheus-app >= "0.2"
  162. rdf = "0.12.0"
  163. reason < "1.7.4"
  164. receive-mail
  165. redis >= "0.2.1"
  166. regenerate
  167. rfc1951 < "1.0.0"
  168. sarek >= "20210823"
  169. sarif >= "0.2.1"
  170. satyrographos >= "0.0.2.7"
  171. semantic_version
  172. sexp_pretty
  173. sill >= "1.3.1"
  174. simple-diff
  175. slug
  176. soupault
  177. spoc >= "20210823"
  178. sqlexpr >= "0.7.1" & < "0.9.0"
  179. swagger
  180. tar < "2.2.0"
  181. tar-format >= "0.2.0"
  182. tar-mirage < "2.2.0"
  183. tar-unix < "2.2.0"
  184. testrunner
  185. tezos-base < "7.4"
  186. tezos-clic < "8.0" | >= "13.0"
  187. tezos-protocol-compiler = "10.2" | = "13.0"
  188. tezos-stdlib-unix >= "7.4"
  189. tezt
  190. timere-parse
  191. touist >= "3.5.0"
  192. tyre >= "0.4"
  193. tyxml >= "4.0.0"
  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. vhd-tool >= "0.12.0"
  203. webmachine
  204. xapi-idl
  205. xe
  206. xen-api-client >= "0.9.6"
  207. xtmpl >= "0.15.0" & < "0.19.0"

Conflicts

None