yesod/yesod-newsfeed/Yesod/RssFeed.hs
2012-04-03 09:51:04 +03:00

74 lines
2.6 KiB
Haskell

{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}
-------------------------------------------------------------------------------
--
-- Module : Yesod.RssFeed
-- Copyright : Patrick Brisbin
-- License : as-is
--
-- Maintainer : Patrick Brisbin <me@pbrisbin.com>
-- Stability : Stable
-- Portability : Portable
--
-------------------------------------------------------------------------------
module Yesod.RssFeed
( rssFeed
, rssLink
, RepRss (..)
, module Yesod.FeedTypes
) where
import Yesod.Core
import Yesod.FeedTypes
import Text.Hamlet (hamlet)
import qualified Data.ByteString.Char8 as S8
import Data.Text (Text, pack)
import Data.Text.Lazy (toStrict)
import Text.XML
import Text.Blaze.Renderer.Text (renderHtml)
newtype RepRss = RepRss Content
instance HasReps RepRss where
chooseRep (RepRss c) _ = return (typeRss, c)
-- | Generate the feed
rssFeed :: Feed (Route master) -> GHandler sub master RepRss
rssFeed feed = do
render <- getUrlRender
return $ RepRss $ toContent $ renderLBS def $ template feed render
template :: Feed url -> (url -> Text) -> Document
template Feed {..} render =
Document (Prologue [] Nothing []) root []
where
root = Element "rss" [("version", "2.0")] $ return $ NodeElement $ Element "channel" [] $ map NodeElement
$ Element "{http://www.w3.org/2005/Atom}link"
[ ("href", render feedLinkSelf)
, ("rel", "self")
, ("type", pack $ S8.unpack typeRss)
] []
: Element "title" [] [NodeContent feedTitle]
: Element "link" [] [NodeContent $ render feedLinkHome]
: Element "description" [] [NodeContent $ toStrict $ renderHtml feedDescription]
: Element "lastBuildDate" [] [NodeContent $ formatRFC822 feedUpdated]
: Element "language" [] [NodeContent feedLanguage]
: map (flip entryTemplate render) feedEntries
entryTemplate :: FeedEntry url -> (url -> Text) -> Element
entryTemplate FeedEntry {..} render = Element "item" [] $ map NodeElement
[ Element "title" [] [NodeContent feedEntryTitle]
, Element "link" [] [NodeContent $ render feedEntryLink]
, Element "guid" [] [NodeContent $ render feedEntryLink]
, Element "pubDate" [] [NodeContent $ formatRFC822 feedEntryUpdated]
, Element "description" [] [NodeContent $ toStrict $ renderHtml feedEntryContent]
]
-- | Generates a link tag in the head of a widget.
rssLink :: Route m
-> Text -- ^ title
-> GWidget s m ()
rssLink r title = toWidgetHead [hamlet|
<link href=@{r} type=#{S8.unpack typeRss} rel="alternate" title=#{title}>
|]