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-only 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-1.9.0.tbz
sha256=5289e0d84f04bef02f1ad2928bef9c817893e777ce828306bcfdfd44fc245abd
md5=bddaed4f386a22cace7850c9c7dac296

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: 06 Apr 2019

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
  3. ocaml >= "4.08"

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. biocaml
  27. bistro < "0.6.0"
  28. bonsai >= "v0.15.0"
  29. calculon
  30. calculon-web
  31. caldav
  32. calendar >= "3.0.0"
  33. camyll
  34. caqti >= "1.7.0"
  35. catala != "0.8.0" & < "0.10.0"
  36. cinaps >= "v0.10.0"
  37. cohttp
  38. coin
  39. conan < "0.0.5"
  40. core_bench
  41. core_extended
  42. cosovo
  43. cowabloga >= "0.4.0"
  44. cucumber
  45. cuid
  46. current
  47. current_web
  48. daypack-lib
  49. debian-formats
  50. decompress < "1.0.0"
  51. dkml-install-installer >= "0.4.0"
  52. dns < "4.4.1"
  53. doi2bib
  54. dose3
  55. dune-release >= "0.2.0"
  56. dunolint >= "0.0.20251006"
  57. dunolint-lib
  58. dunolint-lib-base
  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 < "0.0.4"
  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. nx-text
  104. obelisk >= "0.5.0"
  105. ocaml-lsp-server >= "1.9.0"
  106. ocamlformat >= "0.11.0" & < "0.25.1"
  107. ocamlformat-rpc < "0.21.0"
  108. ocp-build
  109. ocp-index
  110. ocsigen-start
  111. octez-bls12-381-signature
  112. octez-libs < "19.0"
  113. opam-bin >= "0.9.5" & < "1.1.0"
  114. opam-client < "2.2.0"
  115. opam-compiler
  116. opam-core
  117. opam-format >= "2.0.8" & != "2.1.0~beta4"
  118. opam-lib
  119. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  120. opam-state >= "2.2.0"
  121. opam_bin_lib
  122. opium
  123. opium_kernel
  124. oranger
  125. ostap < "0.6"
  126. ozulip
  127. patdiff
  128. pgocaml >= "2.3"
  129. pgx
  130. plato
  131. podge >= "0.3"
  132. ppx_css < "v0.17.0"
  133. ppx_cstubs
  134. ppx_expect < "v0.17.0"
  135. ppx_expect_nobase
  136. ppx_minidebug >= "1.6.0"
  137. ppx_regexp >= "0.3.2"
  138. ppx_test
  139. ppx_tyre
  140. ppxlib >= "0.21.1"
  141. prometheus >= "0.2"
  142. prometheus-app
  143. rdf = "0.12.0"
  144. redis
  145. regenerate
  146. rfc1951 < "1.0.0"
  147. safemoney >= "0.3.0"
  148. saga
  149. sarek
  150. sarif >= "0.2.1"
  151. satyrographos >= "0.0.2.7"
  152. semantic_version
  153. sexp_pretty
  154. simple-diff
  155. slug
  156. snf_mcp
  157. soupault
  158. spoc
  159. swagger
  160. talon
  161. tezos-clic >= "16.0"
  162. tezos-stdlib-unix
  163. tezt
  164. timere-parse
  165. touist >= "3.5.0"
  166. tyre >= "0.4"
  167. tyxml >= "4.2.0"
  168. tyxml-syntax
  169. uri < "4.0.0"
  170. uri-re
  171. user-agent-parser
  172. user-setup
  173. uuuu
  174. validate
  175. vendredi
  176. wasm_of_ocaml-compiler
  177. webmachine
  178. xtmpl = "0.18.0"

Conflicts

None