package re

  1. Overview
  2. Docs
RE is a regular expression library for OCaml

Install 

dune-project
 Dependency

github.com Readme Changelog LGPL-2.0-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-1.10.4.tbz
sha256=83eb3e4300aa9b1dc7820749010f4362ea83524742130524d78c20ce99ca747c
sha512=92b05cf92c389fa8c753f2acca837b15dd05a4a2e8e2bec7a269d2e14c35b1a786d394258376648f80b4b99250ba1900cfe68230b8385aeac153149d9ce56099

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: 27 Apr 2022

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 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. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. benchpress
  25. bibfmt
  26. bio_io >= "0.5.1"
  27. biocaml
  28. bistro < "0.6.0"
  29. bonsai >= "v0.15.0"
  30. caisar < "4.0"
  31. calculon
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. camlp5-buildscripts
  36. camyll
  37. caqti >= "1.7.0"
  38. catala < "1.0.0~alpha"
  39. chamo
  40. cinaps >= "v0.10.0"
  41. cohttp
  42. coin < "0.1.5"
  43. colibri2
  44. commons
  45. conan < "0.0.5"
  46. core_bench
  47. core_extended
  48. cosovo
  49. cowabloga >= "0.4.0"
  50. cucumber
  51. cuid
  52. current
  53. current_web
  54. daypack-lib
  55. debian-formats
  56. decompress < "1.0.0"
  57. dkml-install-installer >= "0.4.0"
  58. dns < "4.4.1"
  59. doi2bib
  60. dose3
  61. dune-glob >= "3.21.0"
  62. dune-release >= "0.2.0"
  63. dunolint >= "0.0.20251006"
  64. dunolint-lib
  65. dunolint-lib-base
  66. duppy >= "0.9.4"
  67. elpi
  68. expect_test_helpers_core
  69. expect_test_helpers_kernel
  70. ez_file
  71. ez_search
  72. fat-filesystem
  73. git-split < "1.0.0"
  74. gpiod
  75. graphql_parser >= "0.11.0"
  76. hardcaml_verify
  77. hardcaml_waveterm
  78. hardcaml_xilinx_components
  79. hlarp >= "0.0.3"
  80. horned_worm
  81. humane-re
  82. icalendar
  83. index
  84. index-bench
  85. irmin-bench
  86. jingoo >= "1.2.21"
  87. js_of_ocaml >= "3.10.0"
  88. js_of_ocaml-compiler >= "3.10.0"
  89. js_of_ocaml-lwt >= "3.10.0"
  90. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  91. js_of_ocaml-ppx >= "3.10.0"
  92. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  93. js_of_ocaml-toplevel >= "3.10.0"
  94. js_of_ocaml-tyxml >= "3.10.0"
  95. jsonschema
  96. jwt
  97. jwto
  98. kappa-library
  99. kubecaml
  100. labrys
  101. ldap >= "2.5.1"
  102. learn-ocaml
  103. ledes
  104. lipsum
  105. magic-trace
  106. mdx
  107. mehari
  108. mparser-re
  109. naboris
  110. netsnmp
  111. ninja_utils
  112. nx-text
  113. obelisk >= "0.5.0"
  114. ocaml-lsp-server >= "1.9.0"
  115. ocamlformat >= "0.11.0"
  116. ocamlformat-mlx
  117. ocamlformat-rpc < "0.21.0"
  118. ocamlmig
  119. ocp-build
  120. ocp-index
  121. ocsigen-start
  122. octez-bls12-381-signature
  123. octez-libs
  124. opam-bin >= "0.9.5" & < "1.1.0"
  125. opam-client
  126. opam-compiler
  127. opam-core
  128. opam-format >= "2.0.8" & != "2.1.0~beta4"
  129. opam-lib
  130. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  131. opam-state >= "2.2.0"
  132. opam_bin_lib
  133. opium
  134. opium_kernel
  135. oranger
  136. ostap
  137. ozulip
  138. pa_ppx_string
  139. patdiff
  140. pgocaml >= "2.3"
  141. pgx
  142. plato
  143. podge >= "0.3"
  144. ppx_css < "v0.17.0"
  145. ppx_cstubs
  146. ppx_expect < "v0.17.0"
  147. ppx_expect_nobase < "v0.17.3.0"
  148. ppx_minidebug >= "1.6.0"
  149. ppx_regexp >= "0.3.2"
  150. ppx_test
  151. ppx_tyre
  152. ppxlib >= "0.21.1"
  153. prometheus >= "0.2"
  154. prometheus-app
  155. pyml_bindgen >= "0.3.1"
  156. raga
  157. rdf >= "0.12.0" & < "1.0.0"
  158. re_parser
  159. redis
  160. regenerate
  161. rfc1951 < "1.0.0"
  162. safemoney >= "0.3.0"
  163. saga
  164. sarek
  165. sarif >= "0.2.1"
  166. satyrographos >= "0.0.2.7"
  167. semantic_version
  168. sexp_pretty
  169. shakuhachi
  170. simple-diff
  171. slug
  172. snf_mcp
  173. soupault
  174. spoc
  175. swagger
  176. talon
  177. testo
  178. testo-lwt
  179. testo-util
  180. tezos-clic >= "16.0"
  181. tezos-stdlib-unix
  182. tezt
  183. timere-parse
  184. touist >= "3.5.0"
  185. tyre >= "0.4"
  186. tyxml >= "4.2.0"
  187. tyxml-syntax
  188. uri < "4.0.0"
  189. uri-re
  190. user-agent-parser
  191. user-setup
  192. uuuu < "0.4.0"
  193. validate
  194. vendredi
  195. wasm_of_ocaml-compiler
  196. webmachine
  197. xtmpl >= "0.18.0"

Conflicts

None