477 lines
15 KiB
Haskell
477 lines
15 KiB
Haskell
{-# LANGUAGE QuasiQuotes #-}
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE MultiParamTypeClasses #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE CPP #-}
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-- | The basic typeclass for a Yesod application.
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module Yesod.Core
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( -- * Type classes
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Yesod (..)
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, YesodDispatch (..)
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, RenderRoute (..)
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-- ** Breadcrumbs
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, YesodBreadcrumbs (..)
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, breadcrumbs
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-- * Utitlities
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, maybeAuthorized
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, widgetToPageContent
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-- * Defaults
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, defaultErrorHandler
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-- * Data types
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, AuthResult (..)
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-- * Misc
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, yesodVersion
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, yesodRender
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) where
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import Yesod.Content
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import Yesod.Handler
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import qualified Paths_yesod_core
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import Data.Version (showVersion)
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import Yesod.Widget
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import Yesod.Request
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import qualified Network.Wai as W
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import Yesod.Internal
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import Yesod.Internal.Session
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import Yesod.Internal.Request
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import Web.ClientSession (getKey, defaultKeyFile)
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import qualified Web.ClientSession as CS
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Char8 as S8
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import qualified Data.ByteString.Lazy as L
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import Data.Monoid
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import Control.Monad.Trans.Writer
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import Control.Monad.Trans.State hiding (get, put)
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import Text.Hamlet
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import Text.Cassius
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import Text.Julius
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import Web.Routes
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import Text.Blaze (preEscapedLazyText)
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import Data.Text.Lazy.Builder (toLazyText)
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import Data.Text.Lazy.Encoding (encodeUtf8)
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import Data.Maybe (fromMaybe)
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import Control.Monad.IO.Class (liftIO)
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import Web.Cookie (parseCookies)
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import qualified Data.Map as Map
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import Data.Time
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#if GHC7
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#define HAMLET hamlet
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#else
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#define HAMLET $hamlet
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#endif
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class Eq u => RenderRoute u where
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renderRoute :: u -> ([String], [(String, String)])
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-- | This class is automatically instantiated when you use the template haskell
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-- mkYesod function. You should never need to deal with it directly.
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class YesodDispatch a master where
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yesodDispatch
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:: Yesod master
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=> a
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-> Maybe CS.Key
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-> [String]
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-> master
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-> (Route a -> Route master)
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-> Maybe W.Application
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yesodRunner :: Yesod master
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=> a
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-> master
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-> (Route a -> Route master)
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-> Maybe CS.Key -> Maybe (Route a) -> GHandler a master ChooseRep -> W.Application
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yesodRunner = defaultYesodRunner
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-- | Define settings for a Yesod applications. The only required setting is
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-- 'approot'; other than that, there are intelligent defaults.
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class RenderRoute (Route a) => Yesod a where
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-- | An absolute URL to the root of the application. Do not include
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-- trailing slash.
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--
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-- If you want to be lazy, you can supply an empty string under the
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-- following conditions:
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--
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-- * Your application is served from the root of the domain.
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--
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-- * You do not use any features that require absolute URLs, such as Atom
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-- feeds and XML sitemaps.
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approot :: a -> String
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-- | The encryption key to be used for encrypting client sessions.
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-- Returning 'Nothing' disables sessions.
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encryptKey :: a -> IO (Maybe CS.Key)
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encryptKey _ = fmap Just $ getKey defaultKeyFile
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-- | Number of minutes before a client session times out. Defaults to
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-- 120 (2 hours).
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clientSessionDuration :: a -> Int
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clientSessionDuration = const 120
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-- | Output error response pages.
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errorHandler :: ErrorResponse -> GHandler sub a ChooseRep
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errorHandler = defaultErrorHandler
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-- | Applies some form of layout to the contents of a page.
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defaultLayout :: GWidget sub a () -> GHandler sub a RepHtml
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defaultLayout w = do
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p <- widgetToPageContent w
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mmsg <- getMessage
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hamletToRepHtml [HAMLET|
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!!!
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<html>
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<head>
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<title>#{pageTitle p}
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^{pageHead p}
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<body>
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$maybe msg <- mmsg
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<p .message>#{msg}
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^{pageBody p}
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|]
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-- | Override the rendering function for a particular URL. One use case for
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-- this is to offload static hosting to a different domain name to avoid
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-- sending cookies.
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urlRenderOverride :: a -> Route a -> Maybe String
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urlRenderOverride _ _ = Nothing
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-- | Determine if a request is authorized or not.
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--
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-- Return 'Nothing' is the request is authorized, 'Just' a message if
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-- unauthorized. If authentication is required, you should use a redirect;
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-- the Auth helper provides this functionality automatically.
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isAuthorized :: Route a
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-> Bool -- ^ is this a write request?
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-> GHandler s a AuthResult
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isAuthorized _ _ = return Authorized
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-- | Determines whether the current request is a write request. By default,
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-- this assumes you are following RESTful principles, and determines this
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-- from request method. In particular, all except the following request
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-- methods are considered write: GET HEAD OPTIONS TRACE.
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--
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-- This function is used to determine if a request is authorized; see
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-- 'isAuthorized'.
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isWriteRequest :: Route a -> GHandler s a Bool
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isWriteRequest _ = do
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wai <- waiRequest
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return $ not $ W.requestMethod wai `elem`
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["GET", "HEAD", "OPTIONS", "TRACE"]
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-- | The default route for authentication.
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--
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-- Used in particular by 'isAuthorized', but library users can do whatever
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-- they want with it.
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authRoute :: a -> Maybe (Route a)
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authRoute _ = Nothing
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-- | A function used to clean up path segments. It returns 'Right' with a
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-- clean path or 'Left' with a new set of pieces the user should be
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-- redirected to. The default implementation enforces:
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--
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-- * No double slashes
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--
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-- * There is no trailing slash.
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--
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-- Note that versions of Yesod prior to 0.7 used a different set of rules
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-- involing trailing slashes.
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cleanPath :: a -> [String] -> Either [String] [String]
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cleanPath _ s =
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if corrected == s
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then Right s
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else Left corrected
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where
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corrected = filter (not . null) s
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-- | Join the pieces of a path together into an absolute URL. This should
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-- be the inverse of 'splitPath'.
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joinPath :: a
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-> String -- ^ application root
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-> [String] -- ^ path pieces
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-> [(String, String)] -- ^ query string
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-> String
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joinPath _ ar pieces qs = ar ++ '/' : encodePathInfo pieces qs
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-- | This function is used to store some static content to be served as an
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-- external file. The most common case of this is stashing CSS and
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-- JavaScript content in an external file; the "Yesod.Widget" module uses
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-- this feature.
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--
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-- The return value is 'Nothing' if no storing was performed; this is the
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-- default implementation. A 'Just' 'Left' gives the absolute URL of the
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-- file, whereas a 'Just' 'Right' gives the type-safe URL. The former is
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-- necessary when you are serving the content outside the context of a
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-- Yesod application, such as via memcached.
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addStaticContent :: String -- ^ filename extension
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-> String -- ^ mime-type
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-> L.ByteString -- ^ content
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-> GHandler sub a (Maybe (Either String (Route a, [(String, String)])))
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addStaticContent _ _ _ = return Nothing
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-- | Whether or not to tie a session to a specific IP address. Defaults to
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-- 'True'.
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sessionIpAddress :: a -> Bool
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sessionIpAddress _ = True
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defaultYesodRunner :: Yesod master
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=> a
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-> master
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-> (Route a -> Route master)
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-> Maybe CS.Key
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-> Maybe (Route a)
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-> GHandler a master ChooseRep
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-> W.Application
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defaultYesodRunner s master toMasterRoute mkey murl handler req = do
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now <- liftIO getCurrentTime
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let getExpires m = fromIntegral (m * 60) `addUTCTime` now
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let exp' = getExpires $ clientSessionDuration master
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let rh = takeWhile (/= ':') $ show $ W.remoteHost req
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let host = if sessionIpAddress master then S8.pack rh else ""
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let session' =
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case mkey of
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Nothing -> []
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Just key -> fromMaybe [] $ do
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raw <- lookup "Cookie" $ W.requestHeaders req
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val <- lookup sessionName $ parseCookies raw
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decodeSession key now host val
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rr <- liftIO $ parseWaiRequest req session' mkey
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let h = do
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case murl of
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Nothing -> handler
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Just url -> do
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isWrite <- isWriteRequest $ toMasterRoute url
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ar <- isAuthorized (toMasterRoute url) isWrite
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case ar of
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Authorized -> return ()
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AuthenticationRequired ->
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case authRoute master of
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Nothing ->
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permissionDenied "Authentication required"
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Just url' -> do
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setUltDest'
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redirect RedirectTemporary url'
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Unauthorized s' -> permissionDenied s'
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handler
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let sessionMap = Map.fromList
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$ filter (\(x, _) -> x /= nonceKey) session'
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yar <- handlerToYAR master s toMasterRoute (yesodRender master) errorHandler rr murl sessionMap h
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let mnonce = reqNonce rr
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return $ yarToResponse (hr mnonce getExpires host exp') yar
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where
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hr mnonce getExpires host exp' hs ct sm =
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hs'''
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where
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sessionVal =
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case (mkey, mnonce) of
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(Just key, Just nonce)
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-> encodeSession key exp' host
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$ Map.toList
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$ Map.insert nonceKey nonce sm
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_ -> S.empty
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hs' =
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case mkey of
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Nothing -> hs
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Just _ -> AddCookie
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(clientSessionDuration master)
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sessionName
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sessionVal
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: hs
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hs'' = map (headerToPair getExpires) hs'
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hs''' = ("Content-Type", ct) : hs''
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data AuthResult = Authorized | AuthenticationRequired | Unauthorized String
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deriving (Eq, Show, Read)
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-- | A type-safe, concise method of creating breadcrumbs for pages. For each
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-- resource, you declare the title of the page and the parent resource (if
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-- present).
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class YesodBreadcrumbs y where
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-- | Returns the title and the parent resource, if available. If you return
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-- a 'Nothing', then this is considered a top-level page.
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breadcrumb :: Route y -> GHandler sub y (String, Maybe (Route y))
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-- | Gets the title of the current page and the hierarchy of parent pages,
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-- along with their respective titles.
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breadcrumbs :: YesodBreadcrumbs y => GHandler sub y (String, [(Route y, String)])
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breadcrumbs = do
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x' <- getCurrentRoute
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tm <- getRouteToMaster
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let x = fmap tm x'
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case x of
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Nothing -> return ("Not found", [])
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Just y -> do
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(title, next) <- breadcrumb y
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z <- go [] next
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return (title, z)
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where
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go back Nothing = return back
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go back (Just this) = do
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(title, next) <- breadcrumb this
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go ((this, title) : back) next
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applyLayout' :: Yesod master
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=> Html -- ^ title
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-> Hamlet (Route master) -- ^ body
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-> GHandler sub master ChooseRep
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applyLayout' title body = fmap chooseRep $ defaultLayout $ do
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setTitle title
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addHamlet body
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-- | The default error handler for 'errorHandler'.
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defaultErrorHandler :: Yesod y => ErrorResponse -> GHandler sub y ChooseRep
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defaultErrorHandler NotFound = do
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r <- waiRequest
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let path' = bsToChars $ W.pathInfo r
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applyLayout' "Not Found"
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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<h1>Not Found
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<p>#{path'}
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|]
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defaultErrorHandler (PermissionDenied msg) =
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applyLayout' "Permission Denied"
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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<h1>Permission denied
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<p>#{msg}
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|]
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defaultErrorHandler (InvalidArgs ia) =
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applyLayout' "Invalid Arguments"
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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<h1>Invalid Arguments
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<ul>
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$forall msg <- ia
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<li>#{msg}
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|]
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defaultErrorHandler (InternalError e) =
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applyLayout' "Internal Server Error"
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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<h1>Internal Server Error
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<p>#{e}
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|]
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defaultErrorHandler (BadMethod m) =
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applyLayout' "Bad Method"
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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<h1>Method Not Supported
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<p>Method "#{m}" not supported
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|]
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-- | Return the same URL if the user is authorized to see it.
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--
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-- Built on top of 'isAuthorized'. This is useful for building page that only
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-- contain links to pages the user is allowed to see.
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maybeAuthorized :: Yesod a
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=> Route a
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-> Bool -- ^ is this a write request?
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-> GHandler s a (Maybe (Route a))
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maybeAuthorized r isWrite = do
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x <- isAuthorized r isWrite
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return $ if x == Authorized then Just r else Nothing
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-- | Convert a widget to a 'PageContent'.
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widgetToPageContent :: (Eq (Route master), Yesod master)
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=> GWidget sub master ()
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-> GHandler sub master (PageContent (Route master))
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widgetToPageContent (GWidget w) = do
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w' <- flip evalStateT 0
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$ runWriterT $ runWriterT $ runWriterT $ runWriterT
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$ runWriterT $ runWriterT $ runWriterT w
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let ((((((((),
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Body body),
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Last mTitle),
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scripts'),
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stylesheets'),
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style),
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jscript),
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Head head') = w'
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let title = maybe mempty unTitle mTitle
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let scripts = map (locationToHamlet . unScript) $ runUniqueList scripts'
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let stylesheets = map (locationToHamlet . unStylesheet)
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$ runUniqueList stylesheets'
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let cssToHtml = preEscapedLazyText . renderCss
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celper :: Cassius url -> Hamlet url
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celper = fmap cssToHtml
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jsToHtml (Javascript b) = preEscapedLazyText $ toLazyText b
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jelper :: Julius url -> Hamlet url
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jelper = fmap jsToHtml
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render <- getUrlRenderParams
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let renderLoc x =
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case x of
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Nothing -> Nothing
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Just (Left s) -> Just s
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Just (Right (u, p)) -> Just $ render u p
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cssLoc <-
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case style of
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Nothing -> return Nothing
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Just s -> do
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x <- addStaticContent "css" "text/css; charset=utf-8"
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$ encodeUtf8 $ renderCassius render s
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return $ renderLoc x
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jsLoc <-
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case jscript of
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Nothing -> return Nothing
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Just s -> do
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x <- addStaticContent "js" "text/javascript; charset=utf-8"
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$ encodeUtf8 $ renderJulius render s
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return $ renderLoc x
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let head'' =
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#if GHC7
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[hamlet|
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#else
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[$hamlet|
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#endif
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$forall s <- scripts
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<script src="^{s}">
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$forall s <- stylesheets
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<link rel="stylesheet" href="^{s}">
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$maybe s <- style
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$maybe s <- cssLoc
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<link rel="stylesheet" href="#{s}">
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$nothing
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<style>^{celper s}
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$maybe j <- jscript
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$maybe s <- jsLoc
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<script src="#{s}">
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$nothing
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<script>^{jelper j}
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\^{head'}
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|]
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return $ PageContent title head'' body
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yesodVersion :: String
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yesodVersion = showVersion Paths_yesod_core.version
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yesodRender :: Yesod y
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=> y
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-> Route y
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-> [(String, String)]
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-> String
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yesodRender y u qs =
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fromMaybe
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(joinPath y (approot y) ps $ qs ++ qs')
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(urlRenderOverride y u)
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where
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(ps, qs') = renderRoute u
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