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. BetterErrors
  18. bancos
  19. bap-byteweight-frontend
  20. bap-callgraph-collator
  21. bap-fsi-benchmark
  22. bap-ida
  23. bap-objdump
  24. bap-print
  25. bap-radare2
  26. bibfmt
  27. bio_io >= "0.5.1"
  28. biocaml
  29. bonsai >= "v0.15.0"
  30. brot
  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. ciao_lwt
  39. cinaps
  40. cohttp
  41. coin < "0.1.5"
  42. colibri2
  43. conan < "0.0.5"
  44. core_bench
  45. core_extended
  46. cosovo
  47. cowabloga >= "0.4.0"
  48. cucumber
  49. cuid
  50. current
  51. current_web
  52. daypack-lib
  53. debian-formats
  54. decompress < "1.0.0"
  55. dns < "4.4.1"
  56. doi2bib
  57. dose3
  58. dune-glob >= "3.21.0"
  59. dune-release >= "0.2.0"
  60. dunolint >= "0.0.20251006"
  61. dunolint-lib
  62. dunolint-lib-base
  63. duppy >= "0.9.5"
  64. elpi
  65. expect_test_helpers_core
  66. expect_test_helpers_kernel
  67. ez_file
  68. ez_search
  69. fat-filesystem
  70. git-split < "1.0.0"
  71. gpiod
  72. graphql_parser >= "0.11.0"
  73. hardcaml_verify
  74. hardcaml_waveterm
  75. hardcaml_xilinx_components
  76. hlarp >= "0.0.3"
  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. jsonschema-core
  93. jsonschema-validation
  94. jwt
  95. jwto
  96. kappa-library
  97. kubecaml
  98. ldap >= "2.5.1"
  99. learn-ocaml
  100. ledes
  101. lipsum
  102. lwt_ppx_to_let_syntax
  103. magic-trace
  104. mdx
  105. mparser-re
  106. naboris
  107. netsnmp
  108. ninja_utils
  109. nx-text
  110. obelisk >= "0.5.0"
  111. ocaml-lsp-server >= "1.9.0"
  112. ocamlformat
  113. ocamlformat-mlx
  114. ocamlformat-rpc < "0.21.0"
  115. ocamlmig
  116. ocgtk
  117. ocp-build
  118. ocp-index
  119. ocsigen-start
  120. opam-bin >= "0.9.5" & < "1.1.0"
  121. opam-client
  122. opam-compiler
  123. opam-core
  124. opam-format >= "2.0.8" & != "2.1.0~beta4"
  125. opam-lib
  126. opam-solver >= "2.0.8" & < "2.1.0" | >= "2.2.0"
  127. opam-state >= "2.2.0"
  128. opam_bin_lib
  129. opium
  130. opium_kernel
  131. oranger
  132. ostap
  133. ozulip
  134. parseff
  135. patdiff
  136. pgocaml >= "2.3"
  137. pgx
  138. plato
  139. podge >= "0.3"
  140. ppx_css < "v0.17.0"
  141. ppx_cstubs
  142. ppx_expect < "v0.17.0"
  143. ppx_expect_nobase < "v0.17.3.0"
  144. ppx_mikmatch
  145. ppx_minidebug >= "1.6.0"
  146. ppx_regexp >= "0.3.2"
  147. ppx_test
  148. ppx_tyre
  149. ppxlib >= "0.21.1"
  150. prometheus >= "0.2"
  151. prometheus-app
  152. pyml_bindgen >= "0.3.1"
  153. raga
  154. rdf < "1.0.0"
  155. re_parser
  156. redis
  157. rfc1951 < "1.0.0"
  158. safemoney >= "0.3.0"
  159. saga
  160. sarek
  161. sarif >= "0.2.1"
  162. satyrographos
  163. semantic_version
  164. sexp_pretty
  165. shakuhachi
  166. simple-diff
  167. slug
  168. smtml >= "0.21.0"
  169. snf_mcp
  170. soupault
  171. spoc
  172. stem
  173. swagger
  174. talon < "1.0.0~alpha3"
  175. testo
  176. testo-lwt
  177. testo-util
  178. tezt
  179. timere-parse
  180. touist >= "3.5.0"
  181. tyre >= "0.4"
  182. tyxml >= "4.2.0"
  183. tyxml-syntax
  184. uri < "4.0.0"
  185. uri-re
  186. user-agent-parser
  187. user-setup
  188. uuuu < "0.4.0"
  189. validate
  190. vendredi
  191. wasm_of_ocaml-compiler
  192. webmachine
  193. wire
  194. xtmpl >= "0.18.0"

Conflicts

None