diff --git a/CHANGES.md b/CHANGES.md new file mode 100644 --- /dev/null +++ b/CHANGES.md @@ -0,0 +1,7 @@ +html-charset changelog +====================== + +Version 0.1.0 +------------- + +Initial release. Released on July 11, 2018. diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,502 @@ + GNU LESSER GENERAL PUBLIC LICENSE + Version 2.1, February 1999 + + Copyright (C) 1991, 1999 Free Software Foundation, Inc. + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + +[This is the first released version of the Lesser GPL. It also counts + as the successor of the GNU Library Public License, version 2, hence + the version number 2.1.] + + Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. 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A `` declaration with a `charset` attribute or an `http-equiv` + attribute set to `Content-Type` and a value set for `charset`. + Note that it looks at only first 1024 bytes. + 3. [Mozilla's Charset Detectors][chardet] heuristics. To be specific, + it delegates to the [charsetdetect-ae] package, a Haskell implementation + of that. + +[html-charset]: https://hackage.haskell.org/package/html-charset +[chardet]: https://www-archive.mozilla.org/projects/intl/chardet.html +[charsetdetect-ae]: https://hackage.haskell.org/package/charsetdetect-ae + + +API +--- + +The package is available on Hackage: *[html-charset]*. + +~~~~ haskell +>>> import Data.ByteString.Lazy +>>> import Text.Html.Encoding.Detection +>>> detect "\xef\xbb\xbf\xe4\xbd\xa0\xe5\xa5\xbd..." +Just "UTF-8" +>>> detect "..." +Just "latin-1" +>>> detect "\xbe\xee\xbc\xad\xbf\xc0\xbc\xbc\xbf\xe4..." +Just "EUC-KR" +~~~~ + +Note that the `detect` function takes a lazy bytestring, not strict. + +Read the [API docs] for details. + + +CLI +--- + +We currently doesn't provide any official binaries. +The CLI program can be installed using Cabal or Stack: *[html-charset]*. + +~~~~ +$ curl https://www.haskell.org/onlinereport/ | html-charset +ASCII +$ curl http://www.bunka.go.jp/kokugo_nihongo/sisaku/joho/joho/ | html-charset +shift_jis +~~~~ + +Although it's less likely, `html-charset` may fail to determine the character +encoding, and for the case it prints nothing (only a line feed, exactly). +You can customize the string to print when it fails by configuring +`-f`/`--on-failure` option. + +Author and license +------------------ + +Witten by [Hong Minhee]. Licensed under [LGPL 2.1] or higher. + +[Hong Minhee]: https://hongminhee.org/ +[LGPL 2.1]: https://www.gnu.org/licenses/lgpl-2.1.html diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/app/Main.hs b/app/Main.hs new file mode 100644 --- /dev/null +++ b/app/Main.hs @@ -0,0 +1,39 @@ +module Main where + +import Data.Semigroup ((<>)) + +import qualified Data.ByteString.Lazy +import Options.Applicative + +import Text.Html.Encoding.Detection + +newtype Detector = Detector + { onFailure :: String + } + +runDetector :: Detector -> IO () +runDetector Detector { onFailure = onFailure' } = do + html <- Data.ByteString.Lazy.getContents + case detect html of + Just encoding -> putStrLn encoding + Nothing -> putStrLn onFailure' + +detector :: Parser Detector +detector = Detector + <$> strOption + ( long "on-failure" + <> short 'f' + <> help "String to print when it fails to detect the character encoding" + <> showDefault + <> value "" + ) + +detectorOpts :: ParserInfo Detector +detectorOpts = info (detector <**> helper) + ( fullDesc + <> progDesc "Detect character encoding of HTML documents/fragments" + ) + +main :: IO () +main = + runDetector =<< execParser detectorOpts diff --git a/html-charset.cabal b/html-charset.cabal new file mode 100644 --- /dev/null +++ b/html-charset.cabal @@ -0,0 +1,84 @@ +-- This file has been generated from package.yaml by hpack version 0.20.0. +-- +-- see: https://github.com/sol/hpack +-- +-- hash: 099e0dc8959de54391d803d7ecc8f5294b7b59d0936610a8c30921c3758bb3b1 + +name: html-charset +version: 0.1.0 +synopsis: Determine character encoding of HTML documents/fragments +description: Please see the README.md on GitHub at <https://github.com/dahlia/html-charset#readme>. +category: Web +homepage: https://github.com/dahlia/html-charset#readme +bug-reports: https://github.com/dahlia/html-charset/issues +author: Hong Minhee <hong.minhee@gmail.com> +maintainer: Hong Minhee <hong.minhee@gmail.com> +copyright: (c) 2018 Hong Minhee +license: LGPL-2.1 +license-file: LICENSE +build-type: Simple +cabal-version: >= 1.10 + +extra-source-files: + CHANGES.md + README.md + +source-repository head + type: git + location: https://github.com/dahlia/html-charset + +library + hs-source-dirs: + src + ghc-options: -Wall -fwarn-incomplete-uni-patterns -fprint-explicit-kinds + build-depends: + attoparsec >=0.12 && <1 + , base >=4.7 && <5 + , bytestring + , charsetdetect-ae >=1.1 && <2 + exposed-modules: + Text.Html.Encoding.Detection + other-modules: + Paths_html_charset + default-language: Haskell2010 + +executable html-charset + main-is: Main.hs + hs-source-dirs: + app + ghc-options: -Wall -fwarn-incomplete-uni-patterns -fprint-explicit-kinds -threaded -rtsopts -with-rtsopts=-N + build-depends: + base >=4.7 && <5 + , bytestring + , html-charset + , optparse-applicative >=0.14 && <1 + other-modules: + Paths_html_charset + default-language: Haskell2010 + +test-suite doctest + type: exitcode-stdio-1.0 + main-is: doctest.hs + hs-source-dirs: + test + ghc-options: -Wall -fwarn-incomplete-uni-patterns -fprint-explicit-kinds -threaded + build-depends: + QuickCheck + , base >=4.7 && <5 + , bytestring + , doctest + , doctest-discover + , html-charset + default-language: Haskell2010 + +test-suite hlint + type: exitcode-stdio-1.0 + main-is: hlint.hs + hs-source-dirs: + test + ghc-options: -Wall -fwarn-incomplete-uni-patterns -fprint-explicit-kinds -threaded + build-depends: + base >=4.7 && <5 + , bytestring + , hlint >=2.1.7 && <2.2 + default-language: Haskell2010 diff --git a/src/Text/Html/Encoding/Detection.hs b/src/Text/Html/Encoding/Detection.hs new file mode 100644 --- /dev/null +++ b/src/Text/Html/Encoding/Detection.hs @@ -0,0 +1,184 @@ +{-# LANGUAGE OverloadedStrings #-} +module Text.Html.Encoding.Detection + ( EncodingName + , detect + , detectBom + , detectMetaCharset + ) where + +import Control.Monad +import Data.Maybe +import Data.Word +import Prelude hiding (drop, take) + +import Data.Attoparsec.ByteString hiding (Done, Fail, Result, parse, take) +import Data.Attoparsec.ByteString.Lazy (Result (..), parse) +import Codec.Text.Detect (detectEncodingName) +import qualified Data.ByteString +import Data.ByteString.Lazy + +-- | Represent a name of text encoding (i.e., @charset@). E.g., @"UTF-8"@. +type EncodingName = String + +-- | Detect the character encoding from a given HTML fragment. The precendence +-- order for determining the character encoding is: +-- +-- 1. A BOM (byte order mark) before any other data in the HTML document itself. +-- (See also 'detectBom' function for details.) +-- 2. A @<meta>@ declaration with a @charset@ attribute or an @http-equiv@ +-- attribute set to @Content-Type@ and a value set for @charset@. +-- Note that it looks at only first 1024 bytes. +-- (See also 'detectMetaCharset' for details.) +-- 3. [Mozilla's Charset +-- Detectors](https://www-archive.mozilla.org/projects/intl/chardet.html) +-- heuristics. To be specific, it delegates to 'detectEncodingName' from the +-- [charsetdetect-ae](https://hackage.haskell.org/package/charsetdetect-ae) +-- package, a Haskell implementation of that. +-- +-- >>> :set -XOverloadedStrings +-- >>> detect "\xef\xbb\xbf\xe4\xbd\xa0\xe5\xa5\xbd<html><head>..." +-- Just "UTF-8" +-- >>> detect "<html><head><meta charset=latin-1>..." +-- Just "latin-1" +-- >>> detect "<html><head><title>\xbe\xee\xbc\xad\xbf\xc0\xbc\xbc\xbf\xe4..." +-- Just "EUC-KR" +-- +-- It may return 'Nothing' if it fails to determine the character encoding, +-- although it's less likely. +detect :: ByteString -> Maybe EncodingName +detect fragment = + listToMaybe $ mapMaybe ($ fragment) + [ detectBom + , detectMetaCharset . take 1024 + , detectEncodingName + ] + +-- | Detect the character encoding from a given HTML fragment by looking the +-- initial BOM (byte order mark). +-- +-- >>> :set -XOverloadedStrings +-- >>> detectBom "\xef\xbb\xbf\xe4\xbd\xa0\xe5\xa5\xbd" +-- Just "UTF-8" +-- >>> detectBom "\xfe\xff\x4f\x60\x59\x7d" +-- Just "UTF-16BE" +-- >>> detectBom "\xff\xfe\x60\x4f\x7d\x59" +-- Just "UTF-16LE" +-- >>> detectBom "\x00\x00\xfe\xff\x00\x00\x4f\x60\x00\x00\x59\x7d" +-- Just "UTF-32BE" +-- >>> detectBom "\xff\xfe\x00\x00\x60\x4f\x00\x00\x7d\x59\x00\x00" +-- Just "UTF-32LE" +-- >>> detectBom "\x84\x31\x95\x33\xc4\xe3\xba\xc3" +-- Just "GB-18030" +-- +-- It returns 'Nothing' if it fails to find no valid BOM sequence. +-- +-- >>> detectBom "foobar" +-- Nothing +detectBom :: ByteString -> Maybe EncodingName +detectBom fragment = + case take 2 fragment of + "\xfe\xff" -> Just "UTF-16BE" + "\xef\xbb" -> if take 1 (drop 2 fragment) == "\xbf" + then Just "UTF-8" + else Nothing + "\x00\x00" -> if take 2 (drop 2 fragment) == "\xfe\xff" + then Just "UTF-32BE" + else Nothing + "\xff\xfe" -> if take 2 (drop 2 fragment) == "\x00\x00" + then Just "UTF-32LE" + else Just "UTF-16LE" + "\x84\x31" -> if take 2 (drop 2 fragment) == "\x95\x33" + then Just "GB-18030" + else Nothing + _ -> Nothing + +-- | Detect the character encoding from a given HTML fragment by looking +-- a @<meta>@ declaration with a @charset@ attribute or an @http-equiv@ +-- attribute set to @Content-Type@ and a value set for @charset@. +-- +-- >>> :set -XOverloadedStrings +-- >>> detectMetaCharset "<html><head><meta charset=utf-8>" +-- Just "utf-8" +-- >>> detectMetaCharset "<html><head><meta charset='EUC-KR'>" +-- Just "EUC-KR" +-- >>> detectMetaCharset "<html><head><meta charset=\"latin-1\"/></head></html>" +-- Just "latin-1" +-- >>> :{ +-- detectMetaCharset +-- "<meta http-equiv=content-type content='text/html; charset=utf-8'>" +-- :} +-- Just "utf-8" +-- +-- Return 'Nothing' if it failed to any appropriate @<meta>@ tag: +-- +-- >>> detectMetaCharset "<html><body></body></html>" +-- Nothing +detectMetaCharset :: ByteString -> Maybe EncodingName +detectMetaCharset fragment = + case parse html fragment of + Fail {} -> Nothing + Done _ r -> decodeAscii <$> r + where + html :: Parser (Maybe Data.ByteString.ByteString) + html = do + metas <- many' $ choice + [ do + -- [^<]+ + void $ takeWhile1 (/= 0x3c) + return Nothing + , metaCharset + , do + -- [<] + void $ word8 0x3c + return Nothing + ] + return $ case catMaybes metas of + [] -> Nothing + name : _ -> Just name + metaCharset :: Parser (Maybe Data.ByteString.ByteString) + metaCharset = do + void $ string "<meta" + void space + candidates <- many' $ choice + [ do + -- [^>Cc]+ + void $ takeWhile1 $ \ c -> c /= 0x3e && c /= 0x43 && c /= 0x63 + return Nothing + , do + -- (?iCHARSET) + void $ string' "CHARSET" + -- [=] + void $ word8 0x3d + -- ["']? + q <- option 0 $ satisfy $ \ c -> c == 0x22 || c == 0x27 + -- [A-Za-z0-9._-]+ + charset <- takeWhile1 $ \ c -> + 0x41 <= c && c <= 0x5a || + 0x61 <= c && c <= 0x7a || + 0x30 <= c && c <= 0x39 || + c == 0x2e || c == 0x5f || c == 0x2d + when (q /= 0) $ void $ word8 q + return $ Just charset + , do + -- [^>] + void $ satisfy (/= 0x3e) + return Nothing + ] + return $ case catMaybes candidates of + [] -> Nothing + name : _ -> Just name + isSpace :: Word8 -> Bool + isSpace c = + -- [ \t\n\xff\r] + c == 0x20 || c == 0x09 || c == 0x0a || c == 0xff || c == 0x0d + space :: Parser Word8 + space = satisfy isSpace + string' :: String -> Parser () + string' s = sequence_ + [ satisfy $ \ i -> + toEnum (fromEnum c) == i || toEnum (fromEnum c + 32) == i + | c <- s + ] + decodeAscii :: Data.ByteString.ByteString -> String + decodeAscii = + fmap (toEnum . fromEnum) . Data.ByteString.unpack diff --git a/test/doctest.hs b/test/doctest.hs new file mode 100644 --- /dev/null +++ b/test/doctest.hs @@ -0,0 +1,1 @@ +{-# OPTIONS_GHC -F -pgmF doctest-discover -optF test/doctest.json #-} diff --git a/test/hlint.hs b/test/hlint.hs new file mode 100644 --- /dev/null +++ b/test/hlint.hs @@ -0,0 +1,12 @@ +import Language.Haskell.HLint (hlint) +import System.Exit (exitFailure, exitSuccess) + +arguments :: [String] +arguments = ["app", "src", "test"] + +main :: IO () +main = do + hlints <- hlint arguments + case hlints of + [] -> exitSuccess + _ -> exitFailure