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. 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. biocaml
  28. bistro < "0.6.0"
  29. bonsai >= "v0.15.0"
  30. brot
  31. calculon
  32. calculon-web
  33. caldav
  34. calendar >= "3.0.0"
  35. caqti >= "1.7.0"
  36. cinaps >= "v0.10.0"
  37. cohttp < "2.4.0"
  38. coin < "0.1.5"
  39. core_bench
  40. core_extended
  41. cowabloga >= "0.4.0"
  42. cuid
  43. daypack-lib
  44. debian-formats
  45. decompress < "1.0.0"
  46. dns < "4.4.1"
  47. doi2bib
  48. dose3
  49. dune-glob >= "3.21.0"
  50. dune-release >= "0.2.0"
  51. dunolint >= "0.0.20251006"
  52. dunolint-lib
  53. dunolint-lib-base
  54. duppy >= "0.9.5"
  55. elpi
  56. expect_test_helpers_core
  57. expect_test_helpers_kernel
  58. ez_file
  59. ez_search
  60. fat-filesystem
  61. git-split < "0.0.4"
  62. graphql_parser >= "0.11.0"
  63. hardcaml_verify
  64. hardcaml_waveterm
  65. hardcaml_xilinx_components
  66. hlarp >= "0.0.3"
  67. horned_worm
  68. humane-re
  69. icalendar
  70. index
  71. index-bench < "1.3.2" | = "1.4.0"
  72. jingoo >= "1.2.21"
  73. js_of_ocaml-compiler >= "3.10.0"
  74. jsonschema
  75. jwt
  76. jwto
  77. kappa-library
  78. kubecaml
  79. labrys
  80. ldap >= "2.5.1"
  81. learn-ocaml
  82. ledes
  83. lipsum
  84. magic-trace
  85. mdx
  86. mparser-re
  87. naboris
  88. netsnmp
  89. nx-text
  90. obelisk >= "0.5.0"
  91. ocaml-lsp-server >= "1.9.0"
  92. ocamlformat >= "0.11.0" & < "0.25.1"
  93. ocamlformat-rpc < "0.21.0"
  94. ocp-build
  95. ocp-index < "1.2"
  96. ocsigen-start
  97. opam-bin >= "0.9.5" & < "1.1.0"
  98. opam-client < "2.1.0"
  99. opam-compiler
  100. opam-core < "2.1.0~beta4"
  101. opam-format >= "2.0.8" & < "2.1.0~beta4"
  102. opam-lib
  103. opam-solver >= "2.0.8" & < "2.1.0"
  104. opam_bin_lib
  105. opium
  106. opium_kernel
  107. oranger < "3.0.1"
  108. ostap < "0.6"
  109. ozulip
  110. patdiff
  111. pgocaml >= "2.3"
  112. pgx
  113. podge >= "0.3"
  114. ppx_css < "v0.17.0"
  115. ppx_cstubs
  116. ppx_expect < "v0.17.0"
  117. ppx_expect_nobase < "v0.17.3.0"
  118. ppx_mikmatch
  119. ppx_minidebug >= "1.6.0"
  120. ppx_regexp >= "0.3.2"
  121. ppx_test
  122. ppx_tyre
  123. prometheus >= "0.2"
  124. prometheus-app
  125. redis
  126. regenerate
  127. rfc1951 < "1.0.0"
  128. safemoney >= "0.3.0"
  129. saga
  130. sarek
  131. sarif >= "0.2.1"
  132. semantic_version
  133. sexp_pretty
  134. simple-diff
  135. slug
  136. smtml >= "0.21.0"
  137. snf_mcp
  138. soupault < "3.2.0"
  139. spoc
  140. swagger
  141. talon < "1.0.0~alpha3"
  142. tezt
  143. touist >= "3.5.0"
  144. tyre < "0.5"
  145. tyxml >= "4.2.0"
  146. tyxml-syntax
  147. uri < "2.2.1"
  148. user-agent-parser
  149. user-setup
  150. uuuu < "0.4.0"
  151. validate
  152. vendredi
  153. wasm_of_ocaml-compiler
  154. webmachine
  155. xtmpl = "0.18.0"

Conflicts

None