package re

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  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-1.12.0.tbz
sha256=a01f2bf22f72c2f4ababd8d3e7635e35c1bf6bc5a41ad6d5a007454ddabad1d4
sha512=f0726826e1e677f7ecdf447d46d814a11d3844ec6e5c0527be8c73c7afdb08aacfca47ea764eda325bcd7064aff07c1d3441c935ee5a0fc99ede8707f81a451d

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: 03 Sep 2024

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 >= "4.12"

Dev Dependencies (1)

  1. ounit2 with-test

  1. alcotest
  2. alcotest-async
  3. alcotest-lwt
  4. alcotest-mirage
  5. alice
  6. ansifmt >= "1.0.0~pre2"
  7. atd >= "2.2.1"
  8. atd-jsonlike
  9. atdcpp
  10. atdd
  11. atdgen >= "2.3.3"
  12. atdgen-runtime = "2.2.1"
  13. atdj >= "2.2.1"
  14. atdpy >= "2.4.1"
  15. atds < "2.3.3"
  16. atdts
  17. aws-config
  18. awsm-codegen
  19. awso
  20. BetterErrors
  21. bancos
  22. bap-byteweight-frontend
  23. bap-callgraph-collator
  24. bap-fsi-benchmark
  25. bap-ida
  26. bap-objdump
  27. bap-print
  28. bap-radare2
  29. bibfmt
  30. bio_io >= "0.5.1"
  31. biocaml
  32. bonsai >= "v0.15.0"
  33. brot
  34. caisar >= "4.0"
  35. calculon
  36. calculon-web
  37. caldav
  38. calendar >= "3.0.0"
  39. camlp5 >= "8.02.01"
  40. camlp5-buildscripts
  41. camyll
  42. caqti >= "1.7.0"
  43. catala
  44. chamo
  45. ciao_lwt
  46. cinaps
  47. cohttp
  48. coin < "0.1.5"
  49. colibri2
  50. commons
  51. conan >= "0.0.6"
  52. core_bench
  53. core_extended
  54. cosovo
  55. cowabloga >= "0.4.0"
  56. crs
  57. cucumber
  58. cuid
  59. current
  60. current_web
  61. daypack-lib
  62. debian-formats
  63. decompress < "1.0.0"
  64. dns < "4.4.1"
  65. doi2bib
  66. dose3
  67. dune-glob >= "3.21.0"
  68. dune-release >= "0.2.0"
  69. dunolint >= "0.0.20251006"
  70. dunolint-lib
  71. dunolint-lib-base
  72. duppy >= "0.9.5"
  73. elpi
  74. expect >= "0.1.0"
  75. expect_test_helpers_core
  76. expect_test_helpers_kernel
  77. ez_file
  78. ez_search
  79. fat-filesystem
  80. git-split < "1.0.0"
  81. gpiod
  82. graphql_parser >= "0.11.0"
  83. hardcaml_verify
  84. hardcaml_waveterm
  85. hardcaml_xilinx_components
  86. hlarp >= "0.0.3"
  87. humane-re
  88. icalendar
  89. index
  90. index-bench
  91. irmin-bench
  92. jingoo >= "1.2.21"
  93. js_of_ocaml >= "3.10.0"
  94. js_of_ocaml-compiler >= "3.10.0"
  95. js_of_ocaml-lwt >= "3.10.0"
  96. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  97. js_of_ocaml-ppx >= "3.10.0"
  98. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  99. js_of_ocaml-toplevel >= "3.10.0"
  100. js_of_ocaml-tyxml >= "3.10.0"
  101. jsonschema
  102. jsonschema-core
  103. jsonschema-validation
  104. jwt
  105. jwto
  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. 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. statocaml_profile
  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