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. ansifmt >= "1.0.0~pre2"
  6. atd >= "2.2.1"
  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. BetterErrors
  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
  45. colibri2
  46. commons
  47. conan >= "0.0.6"
  48. core_bench
  49. core_extended
  50. cosovo
  51. cowabloga >= "0.4.0"
  52. crs
  53. cucumber
  54. cuid
  55. current
  56. current_web
  57. daypack-lib
  58. debian-formats
  59. decompress < "1.0.0"
  60. dkml-install-installer >= "0.4.0"
  61. dns < "4.4.1"
  62. doi2bib
  63. dose3
  64. dune-release >= "0.2.0"
  65. dunolint-lib
  66. duppy >= "0.9.4"
  67. elpi
  68. expect >= "0.1.0"
  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-library
  100. kubecaml
  101. labrys
  102. lastfm >= "0.3.4"
  103. ldap >= "2.5.1"
  104. learn-ocaml
  105. ledes
  106. lipsum
  107. liquidsoap >= "2.3.3"
  108. liquidsoap-core >= "2.3.0"
  109. liquidsoap-lang >= "2.3.0"
  110. MlFront_Cli >= "2.1.4~prerel2" & < "2.3.1"
  111. MlFront_ZipFile
  112. magic-trace
  113. mdx
  114. mehari
  115. mparser-re
  116. naboris
  117. netsnmp
  118. ninja_utils
  119. nx-text
  120. obelisk >= "0.5.0"
  121. ocaml-lsp-server >= "1.9.0"
  122. ocamlformat >= "0.11.0"
  123. ocamlformat-mlx
  124. ocamlformat-rpc < "0.21.0"
  125. ocamlmig
  126. ocp-build
  127. ocp-index
  128. ocsigen-start
  129. ocsigenserver >= "5.1.0"
  130. octez-bls12-381-signature
  131. octez-libs
  132. opam-bin >= "0.9.5" & < "1.1.0"
  133. opam-client
  134. opam-compiler
  135. opam-core
  136. opam-format >= "2.0.8" & != "2.1.0~beta4"
  137. opam-lib
  138. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  139. opam-state >= "2.2.0"
  140. opam_bin_lib
  141. opium
  142. opium_kernel
  143. oranger
  144. orun
  145. ostap
  146. ozulip
  147. pa_ppx_parsetree
  148. pa_ppx_regexp >= "0.04"
  149. pa_ppx_string
  150. patdiff
  151. pgocaml >= "2.3"
  152. pgx
  153. plato
  154. podge >= "0.3"
  155. ppx_css < "v0.17.0"
  156. ppx_cstubs
  157. ppx_expect < "v0.17.0"
  158. ppx_expect_nobase
  159. ppx_minidebug >= "1.6.0"
  160. ppx_regexp >= "0.3.2"
  161. ppx_test
  162. ppx_tyre
  163. ppxlib >= "0.21.1"
  164. prometheus >= "0.2"
  165. prometheus-app
  166. pyml_bindgen >= "0.3.1"
  167. rdf >= "0.12.0"
  168. re_parser
  169. redis
  170. regenerate
  171. rfc1951 < "1.0.0"
  172. safemoney >= "0.3.0"
  173. sarek
  174. sarif >= "0.2.1"
  175. satyrographos >= "0.0.2.7"
  176. semantic_version
  177. sexp_pretty
  178. simple-diff
  179. slug
  180. snf_mcp
  181. soupault
  182. spoc
  183. statocaml_profile
  184. swagger
  185. testo
  186. testo-lwt
  187. testo-util
  188. tezos-clic >= "16.0"
  189. tezos-stdlib-unix
  190. tezt
  191. timere-parse
  192. touist >= "3.5.0"
  193. tyre >= "0.4"
  194. tyxml >= "4.2.0"
  195. tyxml-syntax
  196. uri < "4.0.0"
  197. uri-re
  198. user-agent-parser
  199. user-setup
  200. uuuu
  201. validate
  202. vendredi
  203. wasm_of_ocaml-compiler
  204. webmachine
  205. xtmpl >= "0.18.0"

Conflicts

None