從樹中過濾元素

Created: November-22, 2018

使用 id="article" 查找 div 並刪除所有內部指令碼標記。

#!/usr/bin/env stack
-- stack --resolver lts-7.1 --install-ghc runghc --package text --package lens --package taggy-lens --package string-class --package classy-prelude
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}

import ClassyPrelude
import Control.Lens hiding (children, element)
import Data.String.Class (toText, fromText, toString)
import Data.Text (Text)
import Text.Taggy.Lens
import qualified Text.Taggy.Lens as Taggy
import qualified Text.Taggy.Renderer as Renderer

somehtmlSmall::Text
somehtmlSmall =
    "<!doctype html><html><body>\
    \<div id=\"article\"><div>first</div><div>second</div><script>this should be removed</script><div>third</div></div>\
    \</body></html>"

renderWithoutScriptTag::Text
renderWithoutScriptTag =
    let mArticle::Maybe Taggy.Element
        mArticle =
            (fromText somehtmlSmall) ^? html .
            allAttributed (ix "id" . only "article")
        mArticleFiltered =
            fmap
                (transform
                     (children %~
                      filter (\n -> n ^? element . name /= Just "script")))
                mArticle
    in maybe "" (toText . Renderer.render) mArticleFiltered

main::IO ()
main = print renderWithoutScriptTag
-- outputs:
-- "<div id=\"article\"><div>first</div><div>second</div><div>third</div></div>"

基於 @duplode 的 SO 答案的貢獻