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-1.8.0.tbz
sha256=9b027c415b7d8752477db8923d53f5eabc05179bb34da2f0ee175f4894207b62
md5=765f6f8d3e6ab200866e719ed7e5178d

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 Aug 2018

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. jbuilder >= "1.0+beta10"
  3. ocaml >= "4.02.3"

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. bap-byteweight-frontend
  18. bap-callgraph-collator
  19. bap-fsi-benchmark
  20. bap-ida
  21. bap-objdump
  22. bap-print >= "2.2.0"
  23. bap-radare2
  24. benchpress
  25. bibfmt
  26. biocaml
  27. bistro < "0.6.0"
  28. bonsai >= "v0.15.0"
  29. calculon
  30. calculon-web
  31. caldav
  32. calendar >= "3.0.0"
  33. caqti >= "1.7.0"
  34. cinaps >= "v0.10.0"
  35. cohttp < "2.4.0"
  36. coin < "0.1.5"
  37. core_bench
  38. core_extended
  39. cowabloga >= "0.4.0"
  40. cuid
  41. daypack-lib
  42. debian-formats
  43. decompress < "1.0.0"
  44. dkml-install-installer >= "0.4.0"
  45. dns < "4.4.1"
  46. doi2bib
  47. dose3
  48. dune-release >= "0.2.0"
  49. dunolint >= "0.0.20251006"
  50. dunolint-lib
  51. dunolint-lib-base
  52. duppy >= "0.9.4"
  53. elpi
  54. expect_test_helpers_core
  55. expect_test_helpers_kernel
  56. ez_file
  57. ez_search
  58. fat-filesystem
  59. git-split < "0.0.4"
  60. graphql_parser >= "0.11.0"
  61. hardcaml_verify
  62. hardcaml_waveterm
  63. hardcaml_xilinx_components
  64. hlarp >= "0.0.3"
  65. horned_worm
  66. humane-re
  67. icalendar
  68. index
  69. index-bench < "1.3.2" | = "1.4.0"
  70. jingoo >= "1.2.21"
  71. js_of_ocaml-compiler >= "3.10.0"
  72. jsonschema
  73. jwt
  74. jwto
  75. kappa-library
  76. kubecaml
  77. labrys
  78. ldap >= "2.5.1"
  79. learn-ocaml
  80. ledes
  81. lipsum
  82. magic-trace
  83. mdx
  84. mparser-re
  85. naboris
  86. netsnmp
  87. nx-text
  88. obelisk >= "0.5.0"
  89. ocaml-lsp-server >= "1.9.0"
  90. ocamlformat >= "0.11.0" & < "0.25.1"
  91. ocamlformat-rpc < "0.21.0"
  92. ocp-build
  93. ocp-index < "1.2"
  94. ocsigen-start
  95. opam-bin >= "0.9.5" & < "1.1.0"
  96. opam-client < "2.1.0"
  97. opam-compiler
  98. opam-core < "2.1.0~beta4"
  99. opam-format >= "2.0.8" & < "2.1.0~beta4"
  100. opam-lib
  101. opam-solver >= "2.0.8" & < "2.1.0"
  102. opam_bin_lib
  103. opium
  104. opium_kernel
  105. oranger < "3.0.1"
  106. ostap < "0.6"
  107. ozulip
  108. patdiff
  109. pgocaml >= "2.3"
  110. pgx
  111. podge >= "0.3"
  112. ppx_css < "v0.17.0"
  113. ppx_cstubs
  114. ppx_expect < "v0.17.0"
  115. ppx_expect_nobase < "v0.17.3.0"
  116. ppx_minidebug >= "1.6.0"
  117. ppx_regexp >= "0.3.2"
  118. ppx_test
  119. ppx_tyre
  120. prometheus >= "0.2"
  121. prometheus-app
  122. redis
  123. regenerate
  124. rfc1951 < "1.0.0"
  125. safemoney >= "0.3.0"
  126. saga
  127. sarek
  128. sarif >= "0.2.1"
  129. semantic_version
  130. sexp_pretty
  131. simple-diff
  132. slug
  133. snf_mcp
  134. soupault < "3.2.0"
  135. spoc
  136. swagger
  137. talon
  138. tezos-stdlib-unix < "16.0"
  139. tezt
  140. touist >= "3.5.0"
  141. tyre < "0.5"
  142. tyxml >= "4.2.0"
  143. tyxml-syntax
  144. uri < "2.2.1"
  145. user-agent-parser
  146. user-setup
  147. uuuu < "0.4.0"
  148. validate
  149. vendredi
  150. wasm_of_ocaml-compiler
  151. webmachine
  152. xtmpl = "0.18.0"

Conflicts

None