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. cinaps >= "v0.10.0"
  43. cohttp
  44. coin < "0.1.5"
  45. colibri2
  46. commons
  47. conan = "0.0.5"
  48. core_bench
  49. core_extended
  50. cosovo
  51. cowabloga >= "0.4.0"
  52. cucumber
  53. cuid
  54. current
  55. current_web
  56. daypack-lib
  57. debian-formats
  58. decompress < "1.0.0"
  59. dns < "4.4.1"
  60. doi2bib
  61. dose3
  62. dune-glob >= "3.21.0"
  63. dune-release >= "0.2.0"
  64. dunolint >= "0.0.20251006"
  65. dunolint-lib
  66. dunolint-lib-base
  67. duppy >= "0.9.5"
  68. elpi
  69. expect_test_helpers_core
  70. expect_test_helpers_kernel
  71. ez_file
  72. ez_search
  73. fat-filesystem
  74. git-split < "1.0.0"
  75. gpiod
  76. graphql_parser >= "0.11.0"
  77. hardcaml_verify
  78. hardcaml_waveterm
  79. hardcaml_xilinx_components
  80. hlarp >= "0.0.3"
  81. horned_worm
  82. humane-re
  83. icalendar
  84. index
  85. index-bench
  86. irmin-bench
  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. jsonschema
  97. jwt
  98. jwto
  99. kappa-agents >= "4.1.3"
  100. kappa-binaries >= "4.1.3"
  101. kappa-library
  102. kubecaml
  103. labrys
  104. lastfm >= "0.3.4"
  105. ldap >= "2.5.1"
  106. learn-ocaml
  107. ledes
  108. lipsum
  109. liquidsoap >= "2.3.3"
  110. liquidsoap-core >= "2.3.0"
  111. liquidsoap-lang >= "2.3.0"
  112. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  113. MlFront_Core >= "2.4.2.30"
  114. MlFront_ZipFile
  115. magic-trace
  116. mdx
  117. mehari
  118. mparser-re
  119. naboris
  120. netsnmp
  121. ninja_utils
  122. nx-text
  123. obelisk >= "0.5.0"
  124. ocaml-lsp-server >= "1.9.0"
  125. ocamlformat >= "0.11.0"
  126. ocamlformat-mlx
  127. ocamlformat-rpc < "0.21.0"
  128. ocamlmig
  129. ocp-build
  130. ocp-index
  131. ocsigen-start
  132. ocsigenserver >= "5.1.0"
  133. opam-bin >= "0.9.5" & < "1.1.0"
  134. opam-client
  135. opam-compiler
  136. opam-core
  137. opam-format >= "2.0.8" & != "2.1.0~beta4"
  138. opam-lib
  139. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  140. opam-state >= "2.2.0"
  141. opam_bin_lib
  142. opium
  143. opium_kernel
  144. oranger
  145. orun
  146. ostap
  147. ozulip
  148. pa_ppx_parsetree
  149. pa_ppx_regexp < "0.04"
  150. pa_ppx_string
  151. patdiff
  152. pgocaml >= "2.3"
  153. pgx
  154. plato
  155. podge >= "0.3"
  156. ppx_css < "v0.17.0"
  157. ppx_cstubs
  158. ppx_expect < "v0.17.0"
  159. ppx_expect_nobase < "v0.17.3.0"
  160. ppx_minidebug >= "1.6.0"
  161. ppx_regexp >= "0.3.2"
  162. ppx_test
  163. ppx_tyre
  164. ppxlib >= "0.21.1"
  165. prometheus >= "0.2"
  166. prometheus-app
  167. pyml_bindgen >= "0.3.1"
  168. raga
  169. rdf >= "0.12.0"
  170. re_parser
  171. redis
  172. regenerate
  173. regrade
  174. rfc1951 < "1.0.0"
  175. safemoney >= "0.3.0"
  176. saga
  177. sarek
  178. sarif >= "0.2.1"
  179. satyrographos >= "0.0.2.7"
  180. semantic_version
  181. sexp_pretty
  182. shakuhachi
  183. simple-diff
  184. slug
  185. smtml >= "0.21.0"
  186. snf_mcp
  187. soupault
  188. spoc
  189. swagger
  190. talon
  191. testo
  192. testo-lwt
  193. testo-util
  194. tezt
  195. timere-parse
  196. touist >= "3.5.0"
  197. tyre >= "0.4"
  198. tyxml >= "4.2.0"
  199. tyxml-syntax
  200. uri < "4.0.0"
  201. uri-re
  202. user-agent-parser
  203. user-setup
  204. uuuu < "0.4.0"
  205. validate
  206. vendredi
  207. wasm_of_ocaml-compiler
  208. webmachine
  209. xtmpl >= "0.18.0"

Conflicts

None