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. chamo
  43. ciao_lwt
  44. cinaps
  45. cohttp
  46. coin < "0.1.5"
  47. colibri2
  48. commons
  49. conan = "0.0.5"
  50. core_bench
  51. core_extended
  52. cosovo
  53. cowabloga >= "0.4.0"
  54. cucumber
  55. cuid
  56. current
  57. current_web
  58. daypack-lib
  59. debian-formats
  60. decompress < "1.0.0"
  61. dns < "4.4.1"
  62. doi2bib
  63. dose3
  64. dune-glob >= "3.21.0"
  65. dune-release >= "0.2.0"
  66. dunolint >= "0.0.20251006"
  67. dunolint-lib
  68. dunolint-lib-base
  69. duppy >= "0.9.5"
  70. elpi
  71. expect_test_helpers_core
  72. expect_test_helpers_kernel
  73. ez_file
  74. ez_search
  75. fat-filesystem
  76. git-split < "1.0.0"
  77. gpiod
  78. graphql_parser >= "0.11.0"
  79. hardcaml_verify
  80. hardcaml_waveterm
  81. hardcaml_xilinx_components
  82. hlarp >= "0.0.3"
  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. jsonschema-core
  99. jsonschema-validation
  100. jwt
  101. jwto
  102. kappa-agents >= "4.1.3"
  103. kappa-binaries >= "4.1.3"
  104. kappa-library
  105. kubecaml
  106. lastfm >= "0.3.4"
  107. ldap >= "2.5.1"
  108. learn-ocaml
  109. ledes
  110. lipsum
  111. liquidsoap >= "2.3.3"
  112. liquidsoap-core >= "2.3.0"
  113. liquidsoap-lang >= "2.3.0"
  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
  129. ocamlformat-mlx
  130. ocamlformat-rpc < "0.21.0"
  131. ocamlmig
  132. ocgtk
  133. ocp-build
  134. ocp-index
  135. ocsigen-start
  136. ocsigenserver >= "5.1.0"
  137. opam-bin >= "0.9.5" & < "1.1.0"
  138. opam-client
  139. opam-compiler
  140. opam-core
  141. opam-format >= "2.0.8" & != "2.1.0~beta4"
  142. opam-lib
  143. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  144. opam-state >= "2.2.0"
  145. opam_bin_lib
  146. opium
  147. opium_kernel
  148. oranger
  149. orun
  150. ostap
  151. ozulip
  152. pa_ppx_parsetree
  153. pa_ppx_regexp < "0.04"
  154. pa_ppx_string
  155. parseff
  156. patdiff
  157. pgocaml >= "2.3"
  158. pgx
  159. plato
  160. podge >= "0.3"
  161. ppx_css < "v0.17.0"
  162. ppx_cstubs
  163. ppx_expect < "v0.17.0"
  164. ppx_expect_nobase < "v0.17.3.0"
  165. ppx_mikmatch
  166. ppx_minidebug >= "1.6.0"
  167. ppx_regexp >= "0.3.2"
  168. ppx_test
  169. ppx_tyre
  170. ppxlib >= "0.21.1"
  171. prometheus >= "0.2"
  172. prometheus-app
  173. pyml_bindgen >= "0.3.1"
  174. raga
  175. rdf
  176. re_parser
  177. redis
  178. regrade
  179. rfc1951 < "1.0.0"
  180. safemoney >= "0.3.0"
  181. saga
  182. sarek
  183. sarif >= "0.2.1"
  184. satyrographos
  185. semantic_version
  186. sexp_pretty
  187. shakuhachi
  188. simple-diff
  189. slug
  190. smtml >= "0.21.0"
  191. snf_mcp
  192. soupault
  193. spectrum >= "0.7.0"
  194. spectrum_capabilities
  195. spectrum_palette_ppx
  196. spectrum_tools
  197. spoc
  198. stem
  199. swagger
  200. talon < "1.0.0~alpha3"
  201. testcontainers
  202. testo
  203. testo-lwt
  204. testo-util
  205. tezt
  206. timere-parse
  207. touist >= "3.5.0"
  208. tyre >= "0.4"
  209. tyxml >= "4.2.0"
  210. tyxml-syntax
  211. uri < "4.0.0"
  212. uri-re
  213. user-agent-parser
  214. user-setup
  215. uuuu < "0.4.0"
  216. validate
  217. vendredi
  218. wasm_of_ocaml-compiler
  219. webmachine
  220. wire
  221. xtmpl >= "0.18.0"

Conflicts

None