pcre-heavy: A regexp (regex) library on top of pcre-light you can actually use.

[ library, public-domain, web ] [ Propose Tags ]

A PCRE-based regular expressions library with support for multiple matches and replacements. Based on pcre-light. Takes and returns convertible strings everywhere. Includes a QuasiQuoter for regexps that does compile time checking.


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Versions [RSS] 0.1.0, 0.2.0, 0.2.1, 0.2.2, 0.2.3, 0.2.4, 0.2.5, 1.0.0, 1.0.0.1, 1.0.0.2, 1.0.0.3
Dependencies base (>=4.3.0.0 && <5), base-compat (>=0.8.0), bytestring, pcre-light, semigroups, string-conversions, template-haskell (>=2.16.0.0) [details]
License LicenseRef-PublicDomain
Copyright 2015-2022 Val Packett <val@packett.cool>
Author Val Packett
Maintainer val@packett.cool
Revised Revision 1 made by myfreeweb at 2022-10-16T14:10:17Z
Category Web
Home page https://codeberg.org/valpackett/pcre-heavy
Bug tracker https://codeberg.org/valpackett/pcre-heavy/issues
Source repo head: git clone https://codeberg.org/valpackett/pcre-heavy.git
Uploaded by myfreeweb at 2022-10-16T14:05:53Z
Distributions Arch:1.0.0.3, LTSHaskell:1.0.0.3, NixOS:1.0.0.3, Stackage:1.0.0.3
Downloads 11285 total (90 in the last 30 days)
Rating 2.5 (votes: 5) [estimated by Bayesian average]
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Status Docs available [build log]
All reported builds failed as of 2022-10-16 [all 1 reports]

Readme for pcre-heavy-1.0.0.3

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pcre-heavy

Finally! A Haskell regular expressions library that does not suck.

  • based on pcre-light, none of that regex-base complicated pluggable-backend stuff
  • takes and returns ConvertibleStrings everywhere, use ANY STRING TYPE (String, ByteString, Lazy ByteString, Text, Lazy Text) -- but you need a bit more type annotations (or ClassyPrelude's asText, asString, etc.) if you use OverloadedStrings which you probably can't live without
  • a QuasiQuoter for regexps that does compile time checking (BTW, vim2hs has correct syntax highlighting for that!)
  • SEARCHES FOR MULTIPLE MATCHES! DOES REPLACEMENT!

Usage

{-# LANGUAGE QuasiQuotes, FlexibleContexts #-}
import           Text.Regex.PCRE.Heavy

Checking

>>> "https://val.packett.cool" =~ [re|^http.*|]
True

For UnicodeSyntax fans, it's also available as ≈ (U+2248 ALMOST EQUAL TO):

>>> "https://val.packett.cool" ≈ [re|^http.*|]
True

Matching (Searching)

(You can use any string type, not just String!)

scan returns all matches as pairs like (fullmatch, [group, group...]).

>>> scan [re|\s*entry (\d+) (\w+)\s*&?|] " entry 1 hello  &entry 2 hi" :: [(String, [String])]
[
  (" entry 1 hello  &", ["1", "hello"])
, ("entry 2 hi",        ["2", "hi"])
]

It is lazy! If you only need the first match, use head (or, much better, headMay from safe) -- no extra work will be performed!

>>> headMay $ scan [re|\s*entry (\d+) (\w+)\s*&?|] " entry 1 hello  &entry 2 hi"
Just (" entry 1 hello  &", ["1", "hello"])

Replacement

sub replaces the first match, gsub replaces all matches.

-- You can use a Stringable type as the replacement...
>>> gsub [re|\d+|] "!!!NUMBER!!!" "Copyright (c) 2015 The 000 Group"
"Copyright (c) !!!NUMBER!!! The !!!NUMBER!!! Group"

-- or a (Stringable a => [a] -> a) function -- that will get the groups...
>>> gsub [re|%(\d+)(\w+)|] (\(d:w:_) -> "{" ++ d ++ " of " ++ w ++ "}" :: String) "Hello, %20thing"
"Hello, {20 of thing}"

-- or a (Stringable a => a -> a) function -- that will get the full match...
>>> gsub [re|-\w+|] (\x -> "+" ++ (reverse $ drop 1 x) :: String) "hello -world"
"hello +dlrow"

-- or a (Stringable a => a -> [a] -> a) function.
-- That will get both the full match and the groups.
-- I have no idea why you would want to use that, but that's there :-)

Splitting

split, well, splits.

>>> split [re|%(begin|next|end)%|] "%begin%hello%next%world%end%"
["","hello","world",""]

Options

You can pass pcre-light options by using the somethingO variants of functions (and mkRegexQQ for compile time options):

>>> let myRe = mkRegexQQ [multiline, utf8, ungreedy]
>>> scanO [myRe|\s*entry (\d+) (\w+)\s*&?|] [exec_no_utf8_check] " entry 1 hello  &entry 2 hi" :: [[String]]
>>> gsubO [myRe|\d+|] [exec_notempty] "!!!NUMBER!!!" "Copyright (c) 2015 The 000 Group"

utf8 is passed by default in the re QuasiQuoter.

Development

Use stack to build.
Use ghci to run tests quickly with :test (see the .ghci file).

$ stack build

$ stack test && rm tests.tix

$ stack ghci --ghc-options="-fno-hpc"

Contributing

Please feel free to submit pull requests!

By participating in this project you agree to follow the Contributor Code of Conduct.

License

This is free and unencumbered software released into the public domain.
For more information, please refer to the UNLICENSE file or unlicense.org.