package re

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

Install 

dune-project
 Dependency

github.com Readme Changelog LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception License Edit opam file Versions (20)

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-1.11.0.tbz
sha256=01fc244780c0f6be72ae796b1fb750f367de18624fd75d07ee79782ed6df8d4f
sha512=3e3712cc1266ec1f27620f3508ea2ebba338f4083b07d8a69dccee1facfdc1971a6c39f9deea664d2a62fd7f2cfd2eae816ca4c274acfadaee992a3befc4b757

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: 23 Aug 2023

README

Description

Re is a regular expression library for OCaml. Build status

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 >= "4.03"

Dev Dependencies (1)

  1. ounit 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. bancos
  18. bap-byteweight-frontend
  19. bap-callgraph-collator
  20. bap-fsi-benchmark
  21. bap-ida
  22. bap-objdump
  23. bap-print >= "2.2.0"
  24. bap-radare2
  25. benchpress
  26. bibfmt
  27. bio_io >= "0.5.1"
  28. biocaml
  29. bistro < "0.6.0"
  30. bonsai >= "v0.15.0"
  31. caisar < "4.0"
  32. calculon
  33. calculon-web
  34. caldav
  35. calendar >= "3.0.0"
  36. camlp5 >= "8.02.01"
  37. camlp5-buildscripts
  38. camyll
  39. caqti >= "1.7.0"
  40. catala
  41. chamo
  42. ciao_lwt
  43. cinaps >= "v0.10.0"
  44. cohttp
  45. coin < "0.1.5"
  46. colibri2
  47. commons
  48. conan = "0.0.5"
  49. core_bench
  50. core_extended
  51. cosovo
  52. cowabloga >= "0.4.0"
  53. cucumber
  54. cuid
  55. current
  56. current_web
  57. daypack-lib
  58. debian-formats
  59. decompress < "1.0.0"
  60. dns < "4.4.1"
  61. doi2bib
  62. dose3
  63. dune-glob >= "3.21.0"
  64. dune-release >= "0.2.0"
  65. dunolint >= "0.0.20251006"
  66. dunolint-lib
  67. dunolint-lib-base
  68. duppy >= "0.9.5"
  69. elpi
  70. expect_test_helpers_core
  71. expect_test_helpers_kernel
  72. ez_file
  73. ez_search
  74. fat-filesystem
  75. git-split < "1.0.0"
  76. gpiod
  77. graphql_parser >= "0.11.0"
  78. hardcaml_verify
  79. hardcaml_waveterm
  80. hardcaml_xilinx_components
  81. hlarp >= "0.0.3"
  82. horned_worm
  83. humane-re
  84. icalendar
  85. index
  86. index-bench
  87. irmin-bench
  88. jingoo >= "1.2.21"
  89. js_of_ocaml >= "3.10.0"
  90. js_of_ocaml-compiler >= "3.10.0"
  91. js_of_ocaml-lwt >= "3.10.0"
  92. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  93. js_of_ocaml-ppx >= "3.10.0"
  94. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  95. js_of_ocaml-toplevel >= "3.10.0"
  96. js_of_ocaml-tyxml >= "3.10.0"
  97. jsonschema
  98. jwt
  99. jwto
  100. kappa-agents >= "4.1.3"
  101. kappa-binaries >= "4.1.3"
  102. kappa-library
  103. kubecaml
  104. labrys
  105. lastfm >= "0.3.4"
  106. ldap >= "2.5.1"
  107. learn-ocaml
  108. ledes
  109. lipsum
  110. liquidsoap >= "2.3.3"
  111. liquidsoap-core >= "2.3.0"
  112. liquidsoap-lang >= "2.3.0"
  113. lwt_lint
  114. lwt_ppx_to_let_syntax
  115. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  116. MlFront_Core >= "2.4.2.30"
  117. MlFront_ZipFile
  118. magic-trace
  119. mdx
  120. mehari
  121. mparser-re
  122. naboris
  123. netsnmp
  124. ninja_utils
  125. nx-text
  126. obelisk >= "0.5.0"
  127. ocaml-lsp-server >= "1.9.0"
  128. ocamlformat >= "0.11.0"
  129. ocamlformat-mlx
  130. ocamlformat-rpc < "0.21.0"
  131. ocamlmig
  132. ocp-build
  133. ocp-index
  134. ocsigen-start
  135. ocsigenserver >= "5.1.0"
  136. opam-bin >= "0.9.5" & < "1.1.0"
  137. opam-client
  138. opam-compiler
  139. opam-core
  140. opam-format >= "2.0.8" & != "2.1.0~beta4"
  141. opam-lib
  142. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  143. opam-state >= "2.2.0"
  144. opam_bin_lib
  145. opium
  146. opium_kernel
  147. oranger
  148. orun
  149. ostap
  150. ozulip
  151. pa_ppx_parsetree
  152. pa_ppx_regexp < "0.04"
  153. pa_ppx_string
  154. patdiff
  155. pgocaml >= "2.3"
  156. pgx
  157. plato
  158. podge >= "0.3"
  159. ppx_css < "v0.17.0"
  160. ppx_cstubs
  161. ppx_expect < "v0.17.0"
  162. ppx_expect_nobase < "v0.17.3.0"
  163. ppx_mikmatch
  164. ppx_minidebug >= "1.6.0"
  165. ppx_regexp >= "0.3.2"
  166. ppx_test
  167. ppx_tyre
  168. ppxlib >= "0.21.1"
  169. prometheus >= "0.2"
  170. prometheus-app
  171. pyml_bindgen >= "0.3.1"
  172. raga
  173. rdf >= "0.12.0"
  174. re_parser
  175. redis
  176. regenerate
  177. regrade
  178. rfc1951 < "1.0.0"
  179. safemoney >= "0.3.0"
  180. saga
  181. sarek
  182. sarif >= "0.2.1"
  183. satyrographos >= "0.0.2.7"
  184. semantic_version
  185. sexp_pretty
  186. shakuhachi
  187. simple-diff
  188. slug
  189. smtml >= "0.21.0"
  190. snf_mcp
  191. soupault
  192. spectrum >= "0.7.0"
  193. spectrum_capabilities
  194. spectrum_palette_ppx
  195. spectrum_tools
  196. spoc
  197. swagger
  198. talon
  199. testcontainers
  200. testo
  201. testo-lwt
  202. testo-util
  203. tezt
  204. timere-parse
  205. touist >= "3.5.0"
  206. tyre >= "0.4"
  207. tyxml >= "4.2.0"
  208. tyxml-syntax
  209. uri < "4.0.0"
  210. uri-re
  211. user-agent-parser
  212. user-setup
  213. uuuu < "0.4.0"
  214. validate
  215. vendredi
  216. wasm_of_ocaml-compiler
  217. webmachine
  218. xtmpl >= "0.18.0"

Conflicts

None