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 (23)

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-1.8.0.tbz
sha256=9b027c415b7d8752477db8923d53f5eabc05179bb34da2f0ee175f4894207b62
md5=765f6f8d3e6ab200866e719ed7e5178d

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 Aug 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 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. jbuilder >= "1.0+beta10"
  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. benchpress
  26. biocaml = "0.4.0" | >= "0.8.0"
  27. bistro = "0.5.0"
  28. bonsai >= "v0.15.0"
  29. bulletml
  30. calculon >= "0.2"
  31. calculon-web
  32. caldav
  33. calendar >= "3.0.0"
  34. camlp5 >= "8.00.05" & < "8.02.01"
  35. caqti >= "1.7.0"
  36. ccss >= "1.6"
  37. cinaps >= "v0.10.0"
  38. cohttp < "2.1.3"
  39. coin
  40. core_bench >= "v0.9.0"
  41. core_extended >= "v0.10.0"
  42. cow < "1.2.2"
  43. cowabloga >= "0.4.0"
  44. cuid
  45. daypack-lib
  46. debian-formats
  47. decompress >= "0.8" & < "1.0.0"
  48. dkml-install-installer >= "0.4.0"
  49. dns < "4.0.0"
  50. dog < "0.2.1"
  51. doi2bib >= "0.5.1"
  52. dose
  53. dose3
  54. dune-release >= "0.2.0"
  55. duppy >= "0.9.4"
  56. elpi
  57. expect_test_helpers_core
  58. expect_test_helpers_kernel
  59. ez_file
  60. ez_search
  61. fat-filesystem != "0.12.0"
  62. frag
  63. gensqlite
  64. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  65. git-split < "0.0.4"
  66. git_split
  67. graphql_parser >= "0.11.0"
  68. hardcaml_verify
  69. hardcaml_waveterm
  70. hardcaml_xilinx_components
  71. hlarp >= "0.0.3"
  72. horned_worm
  73. http_router
  74. humane-re
  75. icalendar
  76. imaplet-lwt >= "0.1.9"
  77. index
  78. index-bench < "1.3.2" | = "1.4.0"
  79. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  80. iso-filesystem
  81. jingoo >= "1.2.21"
  82. js_of_ocaml-compiler >= "3.10.0"
  83. jwt
  84. jwto
  85. kappa-library
  86. kubecaml
  87. labrys
  88. ldap >= "2.5.1"
  89. learn-ocaml >= "0.13.0"
  90. libres3 >= "0.3"
  91. lipsum
  92. magic-trace
  93. mbr-format < "1.0.0"
  94. mdx
  95. message-switch
  96. mirage >= "0.10.0" & < "2.4.0"
  97. mirage-bootvar-xen < "0.3.2"
  98. mirage-www < "1.0.0"
  99. mparser-re
  100. mustache < "2.0.0"
  101. naboris
  102. netsnmp
  103. obelisk >= "0.5.0"
  104. ocaml-lsp-server >= "1.7.0"
  105. ocamlformat >= "0.11.0" & < "0.25.1"
  106. ocamlformat-rpc < "0.21.0"
  107. ocp-build >= "1.99.21"
  108. ocp-index >= "1.0.2" & < "1.2"
  109. ocsigen-start >= "1.7.0"
  110. odoc >= "2.0.0" & < "2.1.0"
  111. opam-bin >= "0.9.5" & < "1.1.0"
  112. opam-build-revdeps
  113. opam-client >= "2.0.0~rc2" & < "2.1.0~beta2"
  114. opam-compiler
  115. opam-core < "2.1.0~beta2"
  116. opam-format >= "2.0.8" & < "2.1.0~beta2"
  117. opam-lib
  118. opam-solver >= "2.0.8" & < "2.1.0~beta2"
  119. opam2web >= "1.3.0"
  120. opam_bin_lib
  121. operf-macro
  122. opium >= "0.13.1"
  123. opium_kernel
  124. oranger < "3.0.1"
  125. ostap < "0.6"
  126. ozulip
  127. pa_ppx_regexp < "0.02"
  128. patdiff >= "v0.12.0"
  129. pgocaml >= "2.3"
  130. pgx
  131. podge >= "0.3"
  132. ppx_css < "v0.17.0"
  133. ppx_cstubs
  134. ppx_expect >= "113.33.00" & < "v0.17.0"
  135. ppx_implicits >= "0.1.0"
  136. ppx_minidebug >= "1.0.0"
  137. ppx_orakuda >= "3.0.0"
  138. ppx_regexp >= "0.3.2"
  139. ppx_sqlexpr
  140. ppx_test >= "1.1.0"
  141. ppx_tyre
  142. prometheus >= "0.2"
  143. prometheus-app >= "0.2"
  144. reason < "1.7.4"
  145. receive-mail
  146. redis >= "0.2.1"
  147. regenerate
  148. rfc1951 < "1.0.0"
  149. sarek >= "20210823"
  150. sarif >= "0.2.1"
  151. semantic_version
  152. sexp_pretty
  153. sill >= "1.3.1"
  154. simple-diff
  155. slug
  156. soupault < "3.2.0"
  157. spoc >= "20210823"
  158. sqlexpr >= "0.7.1" & < "0.9.0"
  159. swagger
  160. tar < "2.2.0"
  161. tar-format >= "0.2.0"
  162. tar-mirage < "2.2.0"
  163. tar-unix < "2.2.0"
  164. testrunner
  165. tezos-base < "7.4"
  166. tezos-clic < "8.0" | >= "13.0" & < "16.0"
  167. tezos-protocol-compiler = "10.2" | = "13.0"
  168. tezos-stdlib-unix >= "7.4" & < "16.0"
  169. tezt >= "2.0.0"
  170. touist >= "3.5.0"
  171. tyre < "0.5"
  172. tyxml >= "4.0.0"
  173. tyxml-syntax
  174. uri < "2.2.1"
  175. user-agent-parser
  176. user-setup
  177. uuuu
  178. validate
  179. vendredi
  180. vhd-tool >= "0.12.0"
  181. webmachine
  182. xapi-idl
  183. xe
  184. xen-api-client >= "0.9.6"
  185. xtmpl >= "0.15.0" & < "0.19.0"

Conflicts

None

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