package re

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

Install

Dune Dependency

github.com Readme Changelog LGPL-2.0 with OCaml linking exception License Edit opam file Versions (19)

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.

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

Conflicts

None

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