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 with OCaml 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-1.10.3.tbz
sha256=846546967f3fe31765935dd40a6460a9424337ecce7b12727fcba49480790ebb
sha512=d02103b7b8b8d8bc797341dcc933554745427f3c1b51b54b4ac9ff81badfd68c94726c57548b08e00ca99f3e09741b54b6500e97c19fc0e8fcefd6dfbe71da7f

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: 17 Sep 2021

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 >= "4.02"

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

Conflicts

None