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. 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-buildscripts
  38. camyll
  39. caqti >= "1.7.0"
  40. catala < "1.0.0~beta"
  41. chamo
  42. ciao_lwt
  43. cinaps
  44. cohttp
  45. coin < "0.1.5"
  46. colibri2
  47. commons
  48. conan < "0.0.5"
  49. core_bench
  50. core_extended
  51. cosovo
  52. cowabloga >= "0.4.0"
  53. cucumber
  54. cuid
  55. current
  56. current_web
  57. daypack-lib
  58. debian-formats
  59. decompress < "1.0.0"
  60. dns < "4.4.1"
  61. doi2bib
  62. dose3
  63. dune-glob >= "3.21.0"
  64. dune-release >= "0.2.0"
  65. dunolint >= "0.0.20251006"
  66. dunolint-lib
  67. dunolint-lib-base
  68. duppy >= "0.9.5"
  69. elpi
  70. expect_test_helpers_core
  71. expect_test_helpers_kernel
  72. ez_file
  73. ez_search
  74. fat-filesystem
  75. git-split < "1.0.0"
  76. gpiod
  77. graphql_parser >= "0.11.0"
  78. hardcaml_verify
  79. hardcaml_waveterm
  80. hardcaml_xilinx_components
  81. hlarp >= "0.0.3"
  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. jsonschema-core
  98. jsonschema-validation
  99. jwt
  100. jwto
  101. kappa-library
  102. kubecaml
  103. ldap >= "2.5.1"
  104. learn-ocaml
  105. ledes
  106. lipsum
  107. lwt_ppx_to_let_syntax
  108. magic-trace
  109. mdx
  110. mehari
  111. mnet-cli >= "0.0.3"
  112. mparser-re
  113. naboris
  114. netsnmp
  115. ninja_utils
  116. nx-text
  117. obelisk >= "0.5.0"
  118. ocaml-lsp-server >= "1.9.0"
  119. ocamlformat
  120. ocamlformat-mlx
  121. ocamlformat-rpc < "0.21.0"
  122. ocamlmig
  123. ocgtk
  124. ocp-build
  125. ocp-index
  126. ocsigen-start
  127. opam-bin >= "0.9.5" & < "1.1.0"
  128. opam-client
  129. opam-compiler
  130. opam-core
  131. opam-format >= "2.0.8" & != "2.1.0~beta4"
  132. opam-lib
  133. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  134. opam-state >= "2.2.0"
  135. opam_bin_lib
  136. opium
  137. opium_kernel
  138. oranger
  139. ostap
  140. ozulip
  141. pa_ppx_string
  142. parseff
  143. patdiff
  144. pgocaml >= "2.3"
  145. pgx
  146. plato
  147. podge >= "0.3"
  148. ppx_css < "v0.17.0"
  149. ppx_cstubs
  150. ppx_expect < "v0.17.0"
  151. ppx_expect_nobase < "v0.17.3.0"
  152. ppx_mikmatch
  153. ppx_minidebug >= "1.6.0"
  154. ppx_regexp >= "0.3.2"
  155. ppx_test
  156. ppx_tyre
  157. ppxlib >= "0.21.1"
  158. prometheus >= "0.2"
  159. prometheus-app
  160. pyml_bindgen >= "0.3.1"
  161. raga
  162. rdf < "1.0.0"
  163. re_parser
  164. redis
  165. rfc1951 < "1.0.0"
  166. safemoney >= "0.3.0"
  167. saga
  168. sarek
  169. sarif >= "0.2.1"
  170. satyrographos
  171. semantic_version
  172. sexp_pretty
  173. shakuhachi
  174. simple-diff
  175. slug
  176. smtml >= "0.21.0"
  177. snf_mcp
  178. soupault
  179. spoc
  180. stem
  181. swagger
  182. talon < "1.0.0~alpha3"
  183. testo
  184. testo-lwt
  185. testo-util
  186. tezt
  187. timere-parse
  188. touist >= "3.5.0"
  189. tyre >= "0.4"
  190. tyxml >= "4.2.0"
  191. tyxml-syntax
  192. uri < "4.0.0"
  193. uri-re
  194. user-agent-parser
  195. user-setup
  196. uuuu < "0.4.0"
  197. validate
  198. vendredi
  199. wasm_of_ocaml-compiler
  200. webmachine
  201. wire
  202. xtmpl >= "0.18.0"

Conflicts

None