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. cascade
  39. catala < "1.0.0~beta"
  40. ciao_lwt
  41. cinaps
  42. cohttp
  43. coin < "0.1.5"
  44. colibri2
  45. conan < "0.0.5"
  46. core_bench
  47. core_extended
  48. cosovo
  49. cowabloga >= "0.4.0"
  50. cucumber
  51. cuid
  52. current
  53. current_web
  54. daypack-lib
  55. debian-formats
  56. decompress < "1.0.0"
  57. dns < "4.4.1"
  58. doi2bib
  59. dose3
  60. dune-glob >= "3.21.0"
  61. dune-release >= "0.2.0"
  62. dunolint >= "0.0.20251006"
  63. dunolint-lib
  64. dunolint-lib-base
  65. duppy >= "0.9.5"
  66. elpi
  67. expect_test_helpers_core
  68. expect_test_helpers_kernel
  69. ez_file
  70. ez_search
  71. fat-filesystem
  72. git-split < "1.0.0"
  73. gpiod
  74. graphql_parser >= "0.11.0"
  75. hardcaml_verify
  76. hardcaml_waveterm
  77. hardcaml_xilinx_components
  78. hlarp >= "0.0.3"
  79. humane-re
  80. icalendar
  81. index
  82. index-bench
  83. irmin-bench
  84. jingoo >= "1.2.21"
  85. js_of_ocaml >= "3.10.0"
  86. js_of_ocaml-compiler >= "3.10.0"
  87. js_of_ocaml-lwt >= "3.10.0"
  88. js_of_ocaml-ocamlbuild >= "3.10.0" & < "5.0"
  89. js_of_ocaml-ppx >= "3.10.0"
  90. js_of_ocaml-ppx_deriving_json >= "3.10.0"
  91. js_of_ocaml-toplevel >= "3.10.0"
  92. js_of_ocaml-tyxml >= "3.10.0"
  93. jsonschema
  94. jsonschema-core
  95. jsonschema-validation
  96. jwt
  97. jwto
  98. kappa-library
  99. kubecaml
  100. ldap >= "2.5.1"
  101. learn-ocaml
  102. ledes
  103. lipsum
  104. lwt_ppx_to_let_syntax
  105. magic-trace
  106. mdx
  107. mnet-cli >= "0.0.3"
  108. mparser-re
  109. naboris
  110. netsnmp
  111. ninja_utils
  112. nx-text
  113. obelisk >= "0.5.0"
  114. ocaml-lsp-server >= "1.9.0"
  115. ocamlformat
  116. ocamlformat-mlx
  117. ocamlformat-rpc < "0.21.0"
  118. ocamlmig
  119. ocgtk < "0.1~preview2"
  120. ocp-build
  121. ocp-index
  122. ocsigen-start
  123. opam-bin >= "0.9.5" & < "1.1.0"
  124. opam-client
  125. opam-compiler
  126. opam-core
  127. opam-format >= "2.0.8" & != "2.1.0~beta4"
  128. opam-lib
  129. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  130. opam-state >= "2.2.0"
  131. opam_bin_lib
  132. opium
  133. opium_kernel
  134. oranger
  135. ostap
  136. ozulip
  137. parseff
  138. patdiff
  139. pgocaml >= "2.3"
  140. pgx
  141. plato
  142. playwright
  143. podge >= "0.3"
  144. ppx_css < "v0.17.0"
  145. ppx_cstubs
  146. ppx_expect < "v0.17.0"
  147. ppx_expect_nobase = "v0.17.2.2"
  148. ppx_mikmatch
  149. ppx_minidebug >= "1.6.0"
  150. ppx_regexp >= "0.3.2"
  151. ppx_test
  152. ppx_tyre
  153. ppxlib >= "0.21.1"
  154. prometheus >= "0.2"
  155. prometheus-app
  156. pyml_bindgen >= "0.3.1"
  157. raga
  158. rdf < "1.0.0"
  159. re_parser
  160. redis
  161. rfc1951 < "1.0.0"
  162. safemoney >= "0.3.0"
  163. saga
  164. sarek
  165. sarif >= "0.2.1"
  166. satyrographos
  167. semantic_version
  168. sexp_pretty
  169. shakuhachi
  170. simple-diff
  171. slug
  172. smtml >= "0.21.0"
  173. snf_mcp
  174. soupault
  175. spoc
  176. stem
  177. swagger
  178. talon < "1.0.0~alpha3"
  179. testo
  180. testo-lwt
  181. testo-util
  182. tezt
  183. timere-parse
  184. touist >= "3.5.0"
  185. tw
  186. tyre >= "0.4"
  187. tyxml >= "4.2.0"
  188. tyxml-syntax
  189. uri < "4.0.0"
  190. uri-re
  191. user-agent-parser
  192. user-setup
  193. uuuu < "0.4.0"
  194. validate
  195. vendredi
  196. wasm_of_ocaml-compiler
  197. wax-lib
  198. webmachine
  199. wire < "1.0.0"
  200. xtmpl >= "0.18.0"

Conflicts

None