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-1.8.0.tbz
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. dns < "4.0.0"
  49. dog < "0.2.1"
  50. doi2bib >= "0.5.1"
  51. dose
  52. dose3
  53. dune-release >= "0.2.0"
  54. duppy >= "0.9.4"
  55. elpi
  56. expect_test_helpers_core
  57. expect_test_helpers_kernel
  58. ez_file
  59. ez_search
  60. fat-filesystem != "0.12.0"
  61. frag
  62. gensqlite
  63. git < "1.3.0" | >= "1.9.0" & < "1.10.0"
  64. graphql_parser >= "0.11.0"
  65. hardcaml_verify
  66. hardcaml_waveterm
  67. hardcaml_xilinx_components
  68. hlarp >= "0.0.3"
  69. horned_worm
  70. http_router
  71. humane-re
  72. icalendar
  73. imaplet-lwt >= "0.1.9"
  74. index
  75. index-bench < "1.3.2" | = "1.4.0"
  76. irmin != "0.8.1" & < "0.10.0" | >= "1.0.0" & < "1.2.0"
  77. iso-filesystem
  78. jingoo >= "1.2.21"
  79. js_of_ocaml-compiler >= "3.10.0"
  80. jwt
  81. jwto
  82. kappa-library
  83. kubecaml
  84. labrys
  85. learn-ocaml >= "0.13.0"
  86. libres3 >= "0.3"
  87. lipsum
  88. magic-trace
  89. mbr-format < "1.0.0"
  90. mdx
  91. message-switch
  92. mirage >= "0.10.0" & < "2.4.0"
  93. mirage-bootvar-xen < "0.3.2"
  94. mirage-www < "1.0.0"
  95. mparser-re
  96. mustache < "2.0.0"
  97. naboris
  98. netsnmp
  99. obelisk >= "0.5.0"
  100. ocaml-lsp-server >= "1.7.0"
  101. ocamlformat >= "0.11.0" & < "0.25.1"
  102. ocamlformat-rpc < "0.21.0"
  103. ocp-build >= "1.99.21"
  104. ocp-index >= "1.0.2" & < "1.2"
  105. ocsigen-start >= "1.7.0"
  106. odoc >= "2.0.0" & < "2.1.0"
  107. opam-bin >= "0.9.5" & < "1.1.0"
  108. opam-build-revdeps
  109. opam-client >= "2.0.0~rc2" & < "2.1.0~beta2"
  110. opam-compiler
  111. opam-core < "2.1.0~beta2"
  112. opam-format >= "2.0.8" & < "2.1.0~beta2"
  113. opam-lib
  114. opam-solver >= "2.0.8" & < "2.1.0~beta2"
  115. opam2web >= "1.3.0"
  116. opam_bin_lib
  117. operf-macro
  118. opium >= "0.13.1"
  119. opium_kernel
  120. oranger < "3.0.1"
  121. orun
  122. ostap
  123. ozulip
  124. pa_ppx_regexp < "0.02"
  125. patdiff >= "v0.12.0"
  126. pgocaml >= "2.3"
  127. pgx
  128. podge >= "0.3"
  129. ppx_css
  130. ppx_cstubs
  131. ppx_expect >= "113.33.00"
  132. ppx_implicits >= "0.1.0"
  133. ppx_minidebug >= "1.0.0"
  134. ppx_orakuda >= "3.0.0"
  135. ppx_regexp >= "0.3.2"
  136. ppx_sqlexpr
  137. ppx_test >= "1.1.0"
  138. ppx_tyre
  139. prometheus >= "0.2"
  140. prometheus-app >= "0.2"
  141. reason < "1.7.4"
  142. receive-mail
  143. redis >= "0.2.1"
  144. regenerate
  145. rfc1951 < "1.0.0"
  146. sarek >= "20210823"
  147. sarif >= "0.2.1"
  148. semantic_version
  149. sexp_pretty
  150. sill >= "1.3.1"
  151. simple-diff
  152. slug
  153. soupault < "3.2.0"
  154. spoc >= "20210823"
  155. sqlexpr >= "0.7.1" & < "0.9.0"
  156. swagger
  157. tar < "2.2.0"
  158. tar-format >= "0.2.0"
  159. tar-mirage < "2.2.0"
  160. tar-unix < "2.2.0"
  161. testrunner
  162. tezos-base < "7.4"
  163. tezos-clic < "8.0" | >= "13.0" & < "16.0"
  164. tezos-protocol-compiler = "10.2" | = "13.0"
  165. tezos-stdlib-unix >= "7.4" & < "16.0"
  166. tezt >= "2.0.0"
  167. touist >= "3.5.0"
  168. tyre < "0.5"
  169. tyxml >= "4.0.0"
  170. tyxml-syntax
  171. uri < "2.2.1"
  172. user-agent-parser
  173. user-setup
  174. uuuu
  175. validate
  176. vendredi
  177. vhd-tool >= "0.12.0"
  178. webmachine
  179. xapi-idl
  180. xe
  181. xen-api-client >= "0.9.6"
  182. xtmpl >= "0.15.0" & < "0.19.0"

Conflicts

None