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-1.7.2.tbz
sha256=f04c5ab5278e8967aafe23ba3de1bf18a359d0a6ab19b6d7a37109f9882adad1
md5=d7c94a401d03f4688aabc60cd40217aa

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: 03 Mar 2018

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 library. This makes it easier to port code from that library to Re without any changes beyond replacing the pcre findlib package with re.pcre.

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. base-bytes
  2. jbuilder >= "1.0+beta7"
  3. ocaml >= "4.02.3"

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. awso
  17. BetterErrors
  18. bancos
  19. bap-byteweight-frontend
  20. bap-callgraph-collator
  21. bap-fsi-benchmark
  22. bap-ida
  23. bap-objdump
  24. bap-print
  25. bap-radare2
  26. bibfmt
  27. biocaml
  28. brot
  29. calculon
  30. calculon-web
  31. caldav
  32. calendar >= "3.0.0"
  33. caqti >= "1.7.0"
  34. cinaps < "v0.12.0"
  35. cohttp < "2.4.0"
  36. coin < "0.1.5"
  37. cowabloga >= "0.4.0"
  38. cuid
  39. daypack-lib
  40. debian-formats < "0.1.2"
  41. decompress < "1.0.0"
  42. dns < "4.4.1"
  43. doi2bib
  44. dose3
  45. dune-glob >= "3.21.0"
  46. dune-release >= "0.2.0"
  47. duppy >= "0.9.5"
  48. elpi
  49. fat-filesystem
  50. git-split < "0.0.4"
  51. graphql_parser >= "0.11.0"
  52. hlarp >= "0.0.3"
  53. humane-re
  54. icalendar
  55. index
  56. index-bench < "1.3.2" | = "1.4.0"
  57. jingoo >= "1.2.21"
  58. js_of_ocaml-compiler >= "3.10.0"
  59. jsonschema
  60. jwt
  61. jwto < "0.2.0"
  62. kappa-library
  63. ldap >= "2.5.1"
  64. learn-ocaml
  65. ledes
  66. lipsum
  67. mdx
  68. mparser-re
  69. naboris
  70. nx-text
  71. obelisk >= "0.5.0"
  72. ocaml-lsp-server >= "1.9.0"
  73. ocamlformat < "0.25.1"
  74. ocamlformat-rpc >= "0.19.0" & < "0.21.0"
  75. ocgtk
  76. ocsigen-start
  77. opam-bin >= "0.9.5" & < "1.1.0"
  78. opam-client < "2.1.0"
  79. opam-compiler
  80. opam-core < "2.1.0~beta4"
  81. opam-format >= "2.0.8" & < "2.1.0~beta4"
  82. opam-lib
  83. opam-solver >= "2.0.8" & < "2.1.0"
  84. opam_bin_lib
  85. opium
  86. opium_kernel
  87. oranger < "3.0.1"
  88. ostap < "0.6"
  89. ozulip
  90. pgocaml >= "2.3"
  91. pgx
  92. podge >= "0.3"
  93. ppx_cstubs
  94. ppx_mikmatch
  95. ppx_minidebug >= "1.6.0"
  96. ppx_regexp >= "0.3.2"
  97. ppx_tyre
  98. prometheus >= "0.2"
  99. prometheus-app >= "1.3"
  100. redis
  101. rfc1951 < "1.0.0"
  102. safemoney >= "0.3.0"
  103. saga
  104. sarek
  105. sarif >= "0.2.1"
  106. simple-diff
  107. slug
  108. smtml >= "0.21.0"
  109. snf_mcp
  110. soupault < "3.2.0"
  111. spoc
  112. stem
  113. talon < "1.0.0~alpha3"
  114. tezt
  115. touist >= "3.5.0"
  116. tyre < "0.4"
  117. tyxml >= "4.2.0"
  118. tyxml-syntax
  119. uri < "2.2.1"
  120. user-setup
  121. uuuu < "0.4.0"
  122. validate
  123. wasm_of_ocaml-compiler
  124. webmachine
  125. wire

Conflicts

None