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. doi2bib
  64. dose3
  65. dune-glob >= "3.21.0"
  66. dune-release >= "0.2.0"
  67. dunolint >= "0.0.20251006"
  68. dunolint-lib
  69. dunolint-lib-base
  70. duppy >= "0.9.5"
  71. elpi
  72. expect_test_helpers_core
  73. expect_test_helpers_kernel
  74. ez_file
  75. ez_search
  76. fat-filesystem
  77. git-split < "1.0.0"
  78. gpiod
  79. graphql_parser >= "0.11.0"
  80. hardcaml_verify
  81. hardcaml_waveterm
  82. hardcaml_xilinx_components
  83. hlarp >= "0.0.3"
  84. humane-re
  85. icalendar
  86. index
  87. index-bench
  88. irmin-bench
  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. jsonschema
  99. jsonschema-core
  100. jsonschema-validation
  101. jwt
  102. jwto
  103. kappa-agents >= "4.1.3"
  104. kappa-binaries >= "4.1.3"
  105. kappa-library
  106. kubecaml
  107. lastfm >= "0.3.4"
  108. ldap >= "2.5.1"
  109. learn-ocaml
  110. ledes
  111. lipsum
  112. liquidsoap >= "2.3.3"
  113. liquidsoap-core >= "2.3.0"
  114. liquidsoap-lang >= "2.3.0"
  115. lwt_ppx_to_let_syntax
  116. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  117. MlFront_Core >= "2.4.2.30"
  118. MlFront_ZipFile
  119. magic-trace
  120. mdx
  121. mehari
  122. mnet-cli >= "0.0.3"
  123. mparser-re
  124. naboris
  125. netsnmp
  126. ninja_utils
  127. nx-text
  128. obelisk >= "0.5.0"
  129. ocaml-lsp-server >= "1.9.0"
  130. ocamlformat
  131. ocamlformat-mlx
  132. ocamlformat-rpc < "0.21.0"
  133. ocamlmig
  134. ocgtk
  135. ocp-build
  136. ocp-index
  137. ocsigen-start
  138. ocsigenserver >= "5.1.0"
  139. opam-bin >= "0.9.5" & < "1.1.0"
  140. opam-client
  141. opam-compiler
  142. opam-core
  143. opam-format >= "2.0.8" & != "2.1.0~beta4"
  144. opam-lib
  145. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  146. opam-state >= "2.2.0"
  147. opam_bin_lib
  148. opium
  149. opium_kernel
  150. oranger
  151. orun
  152. ostap
  153. ozulip
  154. pa_ppx_parsetree
  155. pa_ppx_regexp < "0.04"
  156. pa_ppx_string
  157. parseff
  158. patdiff
  159. pgocaml >= "2.3"
  160. pgx
  161. plato
  162. podge >= "0.3"
  163. ppx_css < "v0.17.0"
  164. ppx_cstubs
  165. ppx_expect < "v0.17.0"
  166. ppx_expect_nobase < "v0.17.3.0"
  167. ppx_mikmatch
  168. ppx_minidebug >= "1.6.0"
  169. ppx_regexp >= "0.3.2"
  170. ppx_test
  171. ppx_tyre
  172. ppxlib >= "0.21.1"
  173. prometheus >= "0.2"
  174. prometheus-app
  175. pyml_bindgen >= "0.3.1"
  176. raga
  177. rdf
  178. re_parser
  179. redis
  180. regrade
  181. rfc1951 < "1.0.0"
  182. safemoney >= "0.3.0"
  183. saga
  184. sarek
  185. sarif >= "0.2.1"
  186. satyrographos
  187. semantic_version
  188. sexp_pretty
  189. shakuhachi
  190. simple-diff
  191. slug
  192. smtml >= "0.21.0"
  193. snf_mcp
  194. soupault
  195. spectrum >= "0.7.0"
  196. spectrum_capabilities
  197. spectrum_palette_ppx
  198. spectrum_tools
  199. spoc
  200. stem
  201. swagger
  202. talon < "1.0.0~alpha3"
  203. testcontainers
  204. testo
  205. testo-lwt
  206. testo-util
  207. tezt
  208. timere-parse
  209. touist >= "3.5.0"
  210. tyre >= "0.4"
  211. tyxml >= "4.2.0"
  212. tyxml-syntax
  213. uri < "4.0.0"
  214. uri-re
  215. user-agent-parser
  216. user-setup
  217. uuuu < "0.4.0"
  218. validate
  219. vendredi
  220. wasm_of_ocaml-compiler
  221. webmachine
  222. wire
  223. xtmpl >= "0.18.0"

Conflicts

None