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 with OCaml 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-1.10.3.tbz
sha256=846546967f3fe31765935dd40a6460a9424337ecce7b12727fcba49480790ebb
sha512=d02103b7b8b8d8bc797341dcc933554745427f3c1b51b54b4ac9ff81badfd68c94726c57548b08e00ca99f3e09741b54b6500e97c19fc0e8fcefd6dfbe71da7f

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: 17 Sep 2021

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 >= "2.0"
  3. ocaml >= "4.02"

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. BetterErrors
  17. bancos
  18. bap-byteweight-frontend
  19. bap-callgraph-collator
  20. bap-fsi-benchmark
  21. bap-ida
  22. bap-objdump
  23. bap-print >= "2.2.0"
  24. bap-radare2
  25. benchpress
  26. bibfmt
  27. bio_io >= "0.5.1"
  28. biocaml
  29. bistro < "0.6.0"
  30. bonsai >= "v0.15.0"
  31. calculon
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. camyll
  36. caqti >= "1.7.0"
  37. catala < "1.0.0~beta"
  38. cinaps >= "v0.10.0"
  39. cohttp
  40. coin < "0.1.5"
  41. colibri2
  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 < "1.0.0"
  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. ninja_utils
  107. nx-text
  108. obelisk >= "0.5.0"
  109. ocaml-lsp-server >= "1.9.0"
  110. ocamlformat >= "0.11.0"
  111. ocamlformat-mlx
  112. ocamlformat-rpc < "0.21.0"
  113. ocamlmig
  114. ocp-build
  115. ocp-index
  116. ocsigen-start
  117. opam-bin >= "0.9.5" & < "1.1.0"
  118. opam-client
  119. opam-compiler
  120. opam-core
  121. opam-format >= "2.0.8" & != "2.1.0~beta4"
  122. opam-lib
  123. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  124. opam-state >= "2.2.0"
  125. opam_bin_lib
  126. opium
  127. opium_kernel
  128. oranger
  129. ostap
  130. ozulip
  131. patdiff
  132. pgocaml >= "2.3"
  133. pgx
  134. plato
  135. podge >= "0.3"
  136. ppx_css < "v0.17.0"
  137. ppx_cstubs
  138. ppx_expect < "v0.17.0"
  139. ppx_expect_nobase < "v0.17.3.0"
  140. ppx_minidebug >= "1.6.0"
  141. ppx_regexp >= "0.3.2"
  142. ppx_test
  143. ppx_tyre
  144. ppxlib >= "0.21.1"
  145. prometheus >= "0.2"
  146. prometheus-app
  147. pyml_bindgen >= "0.3.1"
  148. raga
  149. rdf >= "0.12.0" & < "1.0.0"
  150. re_parser
  151. redis
  152. regenerate
  153. rfc1951 < "1.0.0"
  154. safemoney >= "0.3.0"
  155. saga
  156. sarek
  157. sarif >= "0.2.1"
  158. satyrographos >= "0.0.2.7"
  159. semantic_version
  160. sexp_pretty
  161. shakuhachi
  162. simple-diff
  163. slug
  164. smtml >= "0.21.0"
  165. snf_mcp
  166. soupault
  167. spoc
  168. swagger
  169. talon
  170. testo
  171. testo-lwt
  172. testo-util
  173. tezt
  174. timere-parse
  175. touist >= "3.5.0"
  176. tyre >= "0.4"
  177. tyxml >= "4.2.0"
  178. tyxml-syntax
  179. uri < "4.0.0"
  180. uri-re
  181. user-agent-parser
  182. user-setup
  183. uuuu < "0.4.0"
  184. validate
  185. vendredi
  186. wasm_of_ocaml-compiler
  187. webmachine
  188. xtmpl >= "0.18.0"

Conflicts

None