package re

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

Install

Dune Dependency

github.com Readme Changelog LGPL-2.0-only WITH OCaml-LGPL-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-1.9.0.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-lib
  57. duppy >= "0.9.4"
  58. elpi
  59. expect_test_helpers_core
  60. expect_test_helpers_kernel
  61. ez_file
  62. ez_search
  63. fat-filesystem
  64. git-split < "0.0.4"
  65. gpiod
  66. graphql_parser >= "0.11.0"
  67. hardcaml_verify
  68. hardcaml_waveterm
  69. hardcaml_xilinx_components
  70. hlarp >= "0.0.3"
  71. horned_worm
  72. humane-re
  73. icalendar
  74. index
  75. index-bench
  76. irmin-bench
  77. jingoo >= "1.2.21"
  78. js_of_ocaml >= "3.10.0"
  79. js_of_ocaml-compiler >= "3.10.0"
  80. js_of_ocaml-lwt >= "3.10.0"
  81. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  82. js_of_ocaml-ppx >= "3.10.0"
  83. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  84. js_of_ocaml-toplevel >= "3.10.0"
  85. js_of_ocaml-tyxml >= "3.10.0"
  86. jsonschema
  87. jwt
  88. jwto
  89. kappa-library
  90. kubecaml
  91. labrys
  92. ldap >= "2.5.1"
  93. learn-ocaml
  94. ledes
  95. lipsum
  96. magic-trace
  97. mdx
  98. mparser-re
  99. naboris
  100. netsnmp
  101. nx-text
  102. obelisk >= "0.5.0"
  103. ocaml-lsp-server >= "1.9.0"
  104. ocamlformat >= "0.11.0" & < "0.25.1"
  105. ocamlformat-rpc < "0.21.0"
  106. ocp-build
  107. ocp-index
  108. ocsigen-start
  109. octez-bls12-381-signature
  110. octez-libs < "19.0"
  111. opam-bin >= "0.9.5" & < "1.1.0"
  112. opam-client < "2.2.0"
  113. opam-compiler
  114. opam-core
  115. opam-format >= "2.0.8" & != "2.1.0~beta4"
  116. opam-lib
  117. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  118. opam-state >= "2.2.0"
  119. opam_bin_lib
  120. opium
  121. opium_kernel
  122. oranger
  123. ostap < "0.6"
  124. ozulip
  125. patdiff
  126. pgocaml >= "2.3"
  127. pgx
  128. plato
  129. podge >= "0.3"
  130. ppx_css < "v0.17.0"
  131. ppx_cstubs
  132. ppx_expect < "v0.17.0"
  133. ppx_expect_nobase
  134. ppx_minidebug >= "1.6.0"
  135. ppx_regexp >= "0.3.2"
  136. ppx_test
  137. ppx_tyre
  138. ppxlib >= "0.21.1"
  139. prometheus >= "0.2"
  140. prometheus-app
  141. rdf = "0.12.0"
  142. redis
  143. regenerate
  144. rfc1951 < "1.0.0"
  145. safemoney >= "0.3.0"
  146. sarek
  147. sarif >= "0.2.1"
  148. satyrographos >= "0.0.2.7"
  149. semantic_version
  150. sexp_pretty
  151. simple-diff
  152. slug
  153. snf_mcp
  154. soupault
  155. spoc
  156. swagger
  157. tezos-clic >= "16.0"
  158. tezos-stdlib-unix
  159. tezt
  160. timere-parse
  161. touist >= "3.5.0"
  162. tyre >= "0.4"
  163. tyxml >= "4.2.0"
  164. tyxml-syntax
  165. uri < "4.0.0"
  166. uri-re
  167. user-agent-parser
  168. user-setup
  169. uuuu
  170. validate
  171. vendredi
  172. wasm_of_ocaml-compiler
  173. webmachine
  174. xtmpl = "0.18.0"

Conflicts

None

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