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. atd-jsonlike
  7. atdcpp
  8. atdd
  9. atdgen >= "2.3.3"
  10. atdgen-runtime = "2.2.1"
  11. atdj >= "2.2.1"
  12. atdpy >= "2.4.1"
  13. atds < "2.3.3"
  14. atdts
  15. aws-config
  16. awsm-codegen
  17. awso
  18. BetterErrors
  19. bancos
  20. bap-byteweight-frontend
  21. bap-callgraph-collator
  22. bap-fsi-benchmark
  23. bap-ida
  24. bap-objdump
  25. bap-print
  26. bap-radare2
  27. bibfmt
  28. bio_io >= "0.5.1"
  29. biocaml
  30. bonsai >= "v0.15.0"
  31. brot
  32. caisar < "4.0"
  33. calculon
  34. calculon-web
  35. caldav
  36. calendar >= "3.0.0"
  37. camlp5 >= "8.02.01"
  38. camlp5-buildscripts
  39. camyll
  40. caqti >= "1.7.0"
  41. catala
  42. catala-format >= "1.2.0"
  43. chamo
  44. ciao_lwt
  45. cinaps
  46. cohttp
  47. coin < "0.1.5"
  48. colibri2
  49. commons
  50. conan = "0.0.5"
  51. core_bench
  52. core_extended
  53. cosovo
  54. cowabloga >= "0.4.0"
  55. cucumber
  56. cuid
  57. current
  58. current_web
  59. daypack-lib
  60. debian-formats
  61. decompress < "1.0.0"
  62. dns < "4.4.1"
  63. docfd >= "13.0.0"
  64. doi2bib
  65. dose3
  66. dune-glob >= "3.21.0"
  67. dune-release >= "0.2.0"
  68. dunolint >= "0.0.20251006"
  69. dunolint-lib
  70. dunolint-lib-base
  71. duppy >= "0.9.5"
  72. elpi
  73. expect_test_helpers_core
  74. expect_test_helpers_kernel
  75. ez_file
  76. ez_search
  77. fat-filesystem
  78. git-split < "1.0.0"
  79. gpiod
  80. graphql_parser >= "0.11.0"
  81. hardcaml_verify
  82. hardcaml_waveterm
  83. hardcaml_xilinx_components
  84. hlarp >= "0.0.3"
  85. humane-re
  86. icalendar
  87. index
  88. index-bench
  89. irmin-bench
  90. jingoo >= "1.2.21"
  91. js_of_ocaml >= "3.10.0"
  92. js_of_ocaml-compiler >= "3.10.0"
  93. js_of_ocaml-lwt >= "3.10.0"
  94. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  95. js_of_ocaml-ppx >= "3.10.0"
  96. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  97. js_of_ocaml-toplevel >= "3.10.0"
  98. js_of_ocaml-tyxml >= "3.10.0"
  99. jsonschema
  100. jsonschema-core
  101. jsonschema-validation
  102. jwt
  103. jwto
  104. kappa-agents >= "4.1.3"
  105. kappa-binaries >= "4.1.3"
  106. kappa-library
  107. kubecaml
  108. lastfm >= "0.3.4"
  109. ldap >= "2.5.1"
  110. learn-ocaml
  111. ledes
  112. lipsum
  113. liquidsoap >= "2.3.3"
  114. liquidsoap-core >= "2.3.0"
  115. liquidsoap-lang >= "2.3.0"
  116. lwt_ppx_to_let_syntax
  117. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  118. MlFront_Core >= "2.4.2.30"
  119. MlFront_ZipFile
  120. magic-trace
  121. mdx
  122. mehari
  123. mnet-cli >= "0.0.3"
  124. mparser-re
  125. naboris
  126. netsnmp
  127. ninja_utils
  128. nx-text
  129. obelisk >= "0.5.0"
  130. ocaml-lsp-server >= "1.9.0"
  131. ocamlformat
  132. ocamlformat-mlx
  133. ocamlformat-rpc < "0.21.0"
  134. ocamlmig
  135. ocgtk
  136. ocp-build
  137. ocp-index
  138. ocsigen-start
  139. ocsigenserver >= "5.1.0"
  140. opam-bin >= "0.9.5" & < "1.1.0"
  141. opam-client
  142. opam-compiler
  143. opam-core
  144. opam-format >= "2.0.8" & != "2.1.0~beta4"
  145. opam-lib
  146. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  147. opam-state >= "2.2.0"
  148. opam_bin_lib
  149. opium
  150. opium_kernel
  151. oranger
  152. orun
  153. ostap
  154. ozulip
  155. pa_ppx_parsetree
  156. pa_ppx_regexp < "0.04"
  157. pa_ppx_string
  158. parseff
  159. patdiff
  160. pgocaml >= "2.3"
  161. pgx
  162. plato
  163. podge >= "0.3"
  164. ppx_css < "v0.17.0"
  165. ppx_cstubs
  166. ppx_expect < "v0.17.0"
  167. ppx_expect_nobase < "v0.17.3.0"
  168. ppx_mikmatch
  169. ppx_minidebug >= "1.6.0"
  170. ppx_regexp >= "0.3.2"
  171. ppx_test
  172. ppx_tyre
  173. ppxlib >= "0.21.1"
  174. prometheus >= "0.2"
  175. prometheus-app
  176. pyml_bindgen >= "0.3.1"
  177. raga
  178. rdf
  179. re_parser
  180. redis
  181. regrade
  182. rfc1951 < "1.0.0"
  183. safemoney >= "0.3.0"
  184. saga
  185. sarek
  186. sarif >= "0.2.1"
  187. satyrographos
  188. semantic_version
  189. sexp_pretty
  190. shakuhachi
  191. simple-diff
  192. slug
  193. smtml >= "0.21.0"
  194. snf_mcp
  195. soupault
  196. spectrum >= "0.7.0"
  197. spectrum_capabilities
  198. spectrum_palette_ppx
  199. spectrum_tools
  200. spoc
  201. stem
  202. swagger
  203. talon < "1.0.0~alpha3"
  204. testcontainers
  205. testo
  206. testo-lwt
  207. testo-util
  208. tezt
  209. timere-parse
  210. touist >= "3.5.0"
  211. tyre >= "0.4"
  212. tyxml >= "4.2.0"
  213. tyxml-syntax
  214. uri < "4.0.0"
  215. uri-re
  216. user-agent-parser
  217. user-setup
  218. uuuu < "0.4.0"
  219. validate
  220. vendredi
  221. wasm_of_ocaml-compiler
  222. webmachine
  223. wire
  224. xtmpl >= "0.18.0"

Conflicts

None