72 lines
1.9 KiB
Haskell
72 lines
1.9 KiB
Haskell
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-- | Once a target is compiled, the user usually wants to save it to the disk.
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-- This is where the 'Route' type comes in; it determines where a certain target
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-- should be written.
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--
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-- When a route is applied (using 'runRoute'), it either returns a 'Just'
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-- 'FilePath' (meaning the target should be written to that file path), or
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-- 'Nothing' (meaning this target should not be written anywhere).
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--
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module Hakyll.Core.Route
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( Route
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, runRoute
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, idRoute
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, setExtension
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, ifMatch
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) where
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import Data.Monoid (Monoid, mempty, mappend)
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import Control.Monad (mplus)
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import System.FilePath (replaceExtension)
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import Hakyll.Core.Identifier
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import Hakyll.Core.Identifier.Pattern
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-- | Type used for a route
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--
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newtype Route = Route {unRoute :: Identifier -> Maybe FilePath}
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instance Monoid Route where
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mempty = Route $ const Nothing
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mappend (Route f) (Route g) = Route $ \id' -> f id' `mplus` g id'
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-- | Apply a route to an identifier
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--
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runRoute :: Route -> Identifier -> Maybe FilePath
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runRoute = unRoute
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-- | A route that uses the identifier as filepath. For example, the target with
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-- ID @foo\/bar@ will be written to the file @foo\/bar@.
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--
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idRoute :: Route
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idRoute = Route $ Just . toFilePath
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-- | Set (or replace) the extension of a route.
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--
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-- Example:
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--
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-- > runRoute (setExtension "html") "foo/bar"
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--
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-- Result:
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--
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-- > Just "foo/bar.html"
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--
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-- Example:
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--
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-- > runRoute (setExtension "html") "posts/the-art-of-trolling.markdown"
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--
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-- Result:
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--
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-- > Just "posts/the-art-of-trolling.html"
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--
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setExtension :: String -> Route
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setExtension exension = Route $ fmap (flip replaceExtension exension)
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. unRoute idRoute
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-- | Modify a route: apply the route if the identifier matches the given
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-- pattern, fail otherwise.
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--
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ifMatch :: Pattern -> Route -> Route
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ifMatch pattern (Route route) = Route $ \id' ->
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if doesMatch pattern id' then route id'
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else Nothing
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