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 (22)

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
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.

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 < "0.4.3" | >= "1.0.0"
  2. alcotest-async >= "1.3.0"
  3. alcotest-lwt >= "1.3.0"
  4. alcotest-mirage >= "1.3.0"
  5. atd = "2.2.1"
  6. atdd
  7. atdgen >= "2.3.3"
  8. atdgen-runtime = "2.2.1"
  9. atdj >= "2.2.1" & < "20151001.01"
  10. atdpy >= "2.4.1"
  11. atds < "2.3.3"
  12. atdts
  13. aws-config
  14. awsm-codegen
  15. BetterErrors
  16. bap < "1.0.0"
  17. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump < "1.4.0" | >= "1.6.0"
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. bap-server
  25. biocaml >= "0.4.0"
  26. bistro = "0.5.0"
  27. bulletml
  28. calculon >= "0.2"
  29. calculon-web
  30. caldav
  31. calendar >= "3.0.0"
  32. camlp5 >= "8.00.05" & < "8.02.01"
  33. caqti >= "1.7.0"
  34. ccss >= "1.6"
  35. cinaps >= "v0.10.0" & < "v0.12.0"
  36. cohttp < "2.1.3"
  37. coin
  38. core_bench >= "v0.9.0" & < "v0.12.0"
  39. core_extended >= "v0.10.0" & < "v0.12.0"
  40. cow < "1.2.2"
  41. cowabloga >= "0.4.0"
  42. cuid
  43. daypack-lib
  44. debian-formats < "0.1.2"
  45. decompress >= "0.8" & < "1.0.0"
  46. dns < "4.0.0"
  47. dog < "0.2.1"
  48. doi2bib >= "0.5.1"
  49. dose
  50. dose3
  51. dune-release >= "0.2.0"
  52. duppy >= "0.9.4"
  53. elpi
  54. expect_test_helpers_kernel < "v0.12.0"
  55. fat-filesystem != "0.12.0"
  56. frag
  57. gensqlite
  58. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  59. graphql_parser >= "0.11.0"
  60. hlarp >= "0.0.3"
  61. horned_worm < "0.3.3"
  62. http_router
  63. humane-re
  64. icalendar
  65. imaplet-lwt >= "0.1.9"
  66. index
  67. index-bench < "1.3.2" | = "1.4.0"
  68. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  69. iso-filesystem
  70. jingoo >= "1.2.21"
  71. js_of_ocaml-compiler >= "3.10.0"
  72. jwt
  73. jwto < "0.2.0"
  74. kappa-library
  75. labrys
  76. learn-ocaml >= "0.13.0"
  77. libres3 >= "0.3"
  78. lipsum
  79. mbr-format < "1.0.0"
  80. mdx
  81. message-switch
  82. mirage >= "0.10.0" & < "2.4.0"
  83. mirage-bootvar-xen < "0.3.2"
  84. mirage-www < "1.0.0"
  85. mparser-re
  86. mustache < "2.0.0"
  87. naboris
  88. obelisk >= "0.5.0"
  89. ocaml-lsp-server >= "1.7.0"
  90. ocamlformat >= "0.11.0" & < "0.25.1"
  91. ocamlformat-rpc >= "0.19.0" & < "0.21.0"
  92. ocp-index >= "1.0.2" & < "1.2"
  93. ocsigen-start >= "1.7.0"
  94. odoc >= "2.0.0" & < "2.1.0"
  95. opam-bin >= "0.9.5" & < "1.1.0"
  96. opam-build-revdeps
  97. opam-client >= "2.0.0~rc2" & < "2.1.0~beta2"
  98. opam-compiler
  99. opam-core < "2.1.0~beta2"
  100. opam-format >= "2.0.8" & < "2.1.0~beta2"
  101. opam-lib
  102. opam-solver >= "2.0.8" & < "2.1.0~beta2"
  103. opam2web >= "1.3.0"
  104. opam_bin_lib
  105. operf-macro
  106. opium >= "0.13.1"
  107. opium_kernel
  108. oranger < "3.0.1"
  109. orun
  110. ostap
  111. ozulip
  112. pa_ppx_regexp < "0.02"
  113. pgocaml >= "2.3"
  114. pgx
  115. podge >= "0.3"
  116. ppx_cstubs
  117. ppx_expect >= "113.33.00" & < "v0.12.0"
  118. ppx_implicits >= "0.1.0"
  119. ppx_minidebug >= "1.0.0"
  120. ppx_orakuda >= "3.0.0"
  121. ppx_regexp >= "0.3.2"
  122. ppx_sqlexpr
  123. ppx_test >= "1.1.0" & < "1.7.0"
  124. ppx_tyre
  125. prometheus >= "0.2"
  126. reason < "1.7.4"
  127. receive-mail
  128. redis >= "0.2.1"
  129. regenerate
  130. rfc1951 < "1.0.0"
  131. sarek >= "20210823"
  132. sarif >= "0.2.1"
  133. sexp_pretty < "v0.12.0"
  134. sill >= "1.3.1"
  135. simple-diff
  136. slug
  137. soupault < "3.2.0"
  138. spoc >= "20210823"
  139. sqlexpr >= "0.7.1" & < "0.9.0"
  140. tar < "2.2.0"
  141. tar-format >= "0.2.0"
  142. tar-mirage < "2.2.0"
  143. tar-unix < "2.2.0"
  144. testrunner
  145. tezos-base < "7.4"
  146. tezos-clic < "8.0" | >= "13.0" & < "16.0"
  147. tezos-protocol-compiler = "10.2" | = "13.0"
  148. tezos-stdlib-unix >= "7.4" & < "16.0"
  149. tezt >= "2.0.0"
  150. touist >= "3.5.0"
  151. tyre < "0.4"
  152. tyxml >= "4.0.0"
  153. tyxml-syntax
  154. uri < "2.2.1"
  155. user-setup
  156. uuuu
  157. validate
  158. vhd-tool >= "0.12.0"
  159. webmachine
  160. xapi-idl
  161. xe
  162. xen-api-client >= "0.9.6"
  163. xtmpl >= "0.15.0" & < "0.17.0"

Conflicts

None