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
  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-release >= "0.2.0"
  62. dunolint >= "0.0.20251006"
  63. dunolint-lib
  64. dunolint-lib-base
  65. duppy >= "0.9.4"
  66. elpi
  67. expect_test_helpers_core
  68. expect_test_helpers_kernel
  69. ez_file
  70. ez_search
  71. fat-filesystem
  72. git-split < "1.0.0"
  73. gpiod
  74. graphql_parser >= "0.11.0"
  75. hardcaml_verify
  76. hardcaml_waveterm
  77. hardcaml_xilinx_components
  78. hlarp >= "0.0.3"
  79. horned_worm
  80. humane-re
  81. icalendar
  82. index
  83. index-bench
  84. irmin-bench
  85. jingoo >= "1.2.21"
  86. js_of_ocaml >= "3.10.0"
  87. js_of_ocaml-compiler >= "3.10.0"
  88. js_of_ocaml-lwt >= "3.10.0"
  89. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  90. js_of_ocaml-ppx >= "3.10.0"
  91. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  92. js_of_ocaml-toplevel >= "3.10.0"
  93. js_of_ocaml-tyxml >= "3.10.0"
  94. jsonschema
  95. jwt
  96. jwto
  97. kappa-library
  98. kubecaml
  99. labrys
  100. ldap >= "2.5.1"
  101. learn-ocaml
  102. ledes
  103. lipsum
  104. magic-trace
  105. mdx
  106. mehari
  107. mparser-re
  108. naboris
  109. netsnmp
  110. ninja_utils
  111. nx-text
  112. obelisk >= "0.5.0"
  113. ocaml-lsp-server >= "1.9.0"
  114. ocamlformat >= "0.11.0"
  115. ocamlformat-mlx
  116. ocamlformat-rpc < "0.21.0"
  117. ocamlmig
  118. ocp-build
  119. ocp-index
  120. ocsigen-start
  121. octez-bls12-381-signature
  122. octez-libs
  123. opam-bin >= "0.9.5" & < "1.1.0"
  124. opam-client
  125. opam-compiler
  126. opam-core
  127. opam-format >= "2.0.8" & != "2.1.0~beta4"
  128. opam-lib
  129. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  130. opam-state >= "2.2.0"
  131. opam_bin_lib
  132. opium
  133. opium_kernel
  134. oranger
  135. ostap
  136. ozulip
  137. pa_ppx_string
  138. patdiff
  139. pgocaml >= "2.3"
  140. pgx
  141. plato
  142. podge >= "0.3"
  143. ppx_css < "v0.17.0"
  144. ppx_cstubs
  145. ppx_expect < "v0.17.0"
  146. ppx_expect_nobase
  147. ppx_minidebug >= "1.6.0"
  148. ppx_regexp >= "0.3.2"
  149. ppx_test
  150. ppx_tyre
  151. ppxlib >= "0.21.1"
  152. prometheus >= "0.2"
  153. prometheus-app
  154. pyml_bindgen >= "0.3.1"
  155. rdf >= "0.12.0" & < "1.0.0"
  156. re_parser
  157. redis
  158. regenerate
  159. rfc1951 < "1.0.0"
  160. safemoney >= "0.3.0"
  161. saga
  162. sarek
  163. sarif >= "0.2.1"
  164. satyrographos >= "0.0.2.7"
  165. semantic_version
  166. sexp_pretty
  167. simple-diff
  168. slug
  169. snf_mcp
  170. soupault
  171. spoc
  172. swagger
  173. talon
  174. testo
  175. testo-lwt
  176. testo-util
  177. tezos-clic >= "16.0"
  178. tezos-stdlib-unix
  179. tezt
  180. timere-parse
  181. touist >= "3.5.0"
  182. tyre >= "0.4"
  183. tyxml >= "4.2.0"
  184. tyxml-syntax
  185. uri < "4.0.0"
  186. uri-re
  187. user-agent-parser
  188. user-setup
  189. uuuu
  190. validate
  191. vendredi
  192. wasm_of_ocaml-compiler
  193. webmachine
  194. xtmpl >= "0.18.0"

Conflicts

None