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-1.9.0.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. atd-jsonlike
  7. atdcpp
  8. atdd
  9. atdgen >= "2.3.3"
  10. atdgen-runtime = "2.2.1"
  11. atdj >= "2.2.1"
  12. atdpy >= "2.4.1"
  13. atds < "2.3.3"
  14. atdts
  15. aws-config
  16. awsm-codegen
  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 >= "2.2.0"
  25. bap-radare2
  26. benchpress
  27. bibfmt
  28. biocaml
  29. bistro < "0.6.0"
  30. bonsai >= "v0.15.0"
  31. brot
  32. calculon
  33. calculon-web
  34. caldav
  35. calendar >= "3.0.0"
  36. camyll
  37. caqti >= "1.7.0"
  38. catala != "0.8.0" & < "0.10.0"
  39. cinaps >= "v0.10.0"
  40. cohttp
  41. coin < "0.1.5"
  42. conan < "0.0.5"
  43. core_bench
  44. core_extended
  45. cosovo
  46. cowabloga >= "0.4.0"
  47. cucumber
  48. cuid
  49. current
  50. current_web
  51. daypack-lib
  52. debian-formats
  53. decompress < "1.0.0"
  54. dns < "4.4.1"
  55. doi2bib
  56. dose3
  57. dune-glob >= "3.21.0"
  58. dune-release >= "0.2.0"
  59. dunolint >= "0.0.20251006"
  60. dunolint-lib
  61. dunolint-lib-base
  62. duppy >= "0.9.5"
  63. elpi
  64. expect_test_helpers_core
  65. expect_test_helpers_kernel
  66. ez_file
  67. ez_search
  68. fat-filesystem
  69. git-split < "0.0.4"
  70. gpiod
  71. graphql_parser >= "0.11.0"
  72. hardcaml_verify
  73. hardcaml_waveterm
  74. hardcaml_xilinx_components
  75. hlarp >= "0.0.3"
  76. horned_worm
  77. humane-re
  78. icalendar
  79. index
  80. index-bench
  81. irmin-bench
  82. jingoo >= "1.2.21"
  83. js_of_ocaml >= "3.10.0"
  84. js_of_ocaml-compiler >= "3.10.0"
  85. js_of_ocaml-lwt >= "3.10.0"
  86. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  87. js_of_ocaml-ppx >= "3.10.0"
  88. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  89. js_of_ocaml-toplevel >= "3.10.0"
  90. js_of_ocaml-tyxml >= "3.10.0"
  91. jsonschema
  92. jwt
  93. jwto
  94. kappa-library
  95. kubecaml
  96. labrys
  97. ldap >= "2.5.1"
  98. learn-ocaml
  99. ledes
  100. lipsum
  101. magic-trace
  102. mdx
  103. mparser-re
  104. naboris
  105. netsnmp
  106. nx-text
  107. obelisk >= "0.5.0"
  108. ocaml-lsp-server >= "1.9.0"
  109. ocamlformat >= "0.11.0" & < "0.25.1"
  110. ocamlformat-rpc < "0.21.0"
  111. ocp-build
  112. ocp-index
  113. ocsigen-start
  114. opam-bin >= "0.9.5" & < "1.1.0"
  115. opam-client < "2.2.0"
  116. opam-compiler
  117. opam-core
  118. opam-format >= "2.0.8" & != "2.1.0~beta4"
  119. opam-lib
  120. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  121. opam-state >= "2.2.0"
  122. opam_bin_lib
  123. opium
  124. opium_kernel
  125. oranger
  126. ostap < "0.6"
  127. ozulip
  128. parseff
  129. patdiff
  130. pgocaml >= "2.3"
  131. pgx
  132. plato
  133. podge >= "0.3"
  134. ppx_css < "v0.17.0"
  135. ppx_cstubs
  136. ppx_expect < "v0.17.0"
  137. ppx_expect_nobase < "v0.17.3.0"
  138. ppx_mikmatch
  139. ppx_minidebug >= "1.6.0"
  140. ppx_regexp >= "0.3.2"
  141. ppx_test
  142. ppx_tyre
  143. ppxlib >= "0.21.1"
  144. prometheus >= "0.2"
  145. prometheus-app
  146. rdf = "0.12.0"
  147. redis
  148. regenerate
  149. rfc1951 < "1.0.0"
  150. safemoney >= "0.3.0"
  151. saga
  152. sarek
  153. sarif >= "0.2.1"
  154. satyrographos >= "0.0.2.7"
  155. semantic_version
  156. sexp_pretty
  157. simple-diff
  158. slug
  159. smtml >= "0.21.0"
  160. snf_mcp
  161. soupault
  162. spoc
  163. swagger
  164. talon < "1.0.0~alpha3"
  165. tezt
  166. timere-parse
  167. touist >= "3.5.0"
  168. tyre >= "0.4"
  169. tyxml >= "4.2.0"
  170. tyxml-syntax
  171. uri < "4.0.0"
  172. uri-re
  173. user-agent-parser
  174. user-setup
  175. uuuu < "0.4.0"
  176. validate
  177. vendredi
  178. wasm_of_ocaml-compiler
  179. webmachine
  180. xtmpl = "0.18.0"

Conflicts

None