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. 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. awso
  18. BetterErrors
  19. bancos
  20. bap-byteweight-frontend
  21. bap-callgraph-collator
  22. bap-fsi-benchmark
  23. bap-ida
  24. bap-objdump
  25. bap-print
  26. bap-radare2
  27. bibfmt
  28. bio_io >= "0.5.1"
  29. biocaml
  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 < "1.0.0~beta"
  39. ciao_lwt
  40. cinaps
  41. cohttp
  42. coin < "0.1.5"
  43. colibri2
  44. conan < "0.0.5"
  45. core_bench
  46. core_extended
  47. cosovo
  48. cowabloga >= "0.4.0"
  49. cucumber
  50. cuid
  51. current
  52. current_web
  53. daypack-lib
  54. debian-formats
  55. decompress < "1.0.0"
  56. dns < "4.4.1"
  57. doi2bib
  58. dose3
  59. dune-glob >= "3.21.0"
  60. dune-release >= "0.2.0"
  61. dunolint >= "0.0.20251006"
  62. dunolint-lib
  63. dunolint-lib-base
  64. duppy >= "0.9.5"
  65. elpi
  66. expect_test_helpers_core
  67. expect_test_helpers_kernel
  68. ez_file
  69. ez_search
  70. fat-filesystem
  71. git-split < "1.0.0"
  72. gpiod
  73. graphql_parser >= "0.11.0"
  74. hardcaml_verify
  75. hardcaml_waveterm
  76. hardcaml_xilinx_components
  77. hlarp >= "0.0.3"
  78. humane-re
  79. icalendar
  80. index
  81. index-bench
  82. irmin-bench
  83. jingoo >= "1.2.21"
  84. js_of_ocaml >= "3.10.0"
  85. js_of_ocaml-compiler >= "3.10.0"
  86. js_of_ocaml-lwt >= "3.10.0"
  87. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  88. js_of_ocaml-ppx >= "3.10.0"
  89. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  90. js_of_ocaml-toplevel >= "3.10.0"
  91. js_of_ocaml-tyxml >= "3.10.0"
  92. jsonschema
  93. jsonschema-core
  94. jsonschema-validation
  95. jwt
  96. jwto
  97. kappa-library
  98. kubecaml
  99. ldap >= "2.5.1"
  100. learn-ocaml
  101. ledes
  102. lipsum
  103. lwt_ppx_to_let_syntax
  104. magic-trace
  105. mdx
  106. mnet-cli >= "0.0.3"
  107. mparser-re
  108. naboris
  109. netsnmp
  110. ninja_utils
  111. nx-text
  112. obelisk >= "0.5.0"
  113. ocaml-lsp-server >= "1.9.0"
  114. ocamlformat
  115. ocamlformat-mlx
  116. ocamlformat-rpc < "0.21.0"
  117. ocamlmig
  118. ocgtk
  119. ocp-build
  120. ocp-index
  121. ocsigen-start
  122. opam-bin >= "0.9.5" & < "1.1.0"
  123. opam-client
  124. opam-compiler
  125. opam-core
  126. opam-format >= "2.0.8" & != "2.1.0~beta4"
  127. opam-lib
  128. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  129. opam-state >= "2.2.0"
  130. opam_bin_lib
  131. opium
  132. opium_kernel
  133. oranger
  134. ostap
  135. ozulip
  136. parseff
  137. patdiff
  138. pgocaml >= "2.3"
  139. pgx
  140. plato
  141. podge >= "0.3"
  142. ppx_css < "v0.17.0"
  143. ppx_cstubs
  144. ppx_expect < "v0.17.0"
  145. ppx_expect_nobase < "v0.17.3.0"
  146. ppx_mikmatch
  147. ppx_minidebug >= "1.6.0"
  148. ppx_regexp >= "0.3.2"
  149. ppx_test
  150. ppx_tyre
  151. ppxlib >= "0.21.1"
  152. prometheus >= "0.2"
  153. prometheus-app
  154. pyml_bindgen >= "0.3.1"
  155. raga
  156. rdf < "1.0.0"
  157. re_parser
  158. redis
  159. rfc1951 < "1.0.0"
  160. safemoney >= "0.3.0"
  161. saga
  162. sarek
  163. sarif >= "0.2.1"
  164. satyrographos
  165. semantic_version
  166. sexp_pretty
  167. shakuhachi
  168. simple-diff
  169. slug
  170. smtml >= "0.21.0"
  171. snf_mcp
  172. soupault
  173. spoc
  174. stem
  175. swagger
  176. talon < "1.0.0~alpha3"
  177. testo
  178. testo-lwt
  179. testo-util
  180. tezt
  181. timere-parse
  182. touist >= "3.5.0"
  183. tyre >= "0.4"
  184. tyxml >= "4.2.0"
  185. tyxml-syntax
  186. uri < "4.0.0"
  187. uri-re
  188. user-agent-parser
  189. user-setup
  190. uuuu < "0.4.0"
  191. validate
  192. vendredi
  193. wasm_of_ocaml-compiler
  194. webmachine
  195. wire
  196. xtmpl >= "0.18.0"

Conflicts

None