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author | Jasper Van der Jeugt <jaspervdj@gmail.com> | 2011-04-05 22:14:49 +0200 |
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committer | Jasper Van der Jeugt <jaspervdj@gmail.com> | 2011-04-05 22:14:49 +0200 |
commit | 015663657ceca7b168bf7d91fbc2fccc41c40904 (patch) | |
tree | c015978d1eec85981a33d261e32d99d4242acff3 /src/Hakyll/Core/Resource | |
parent | 433f36e6f3efdf95276fe0a5f486db3be2824445 (diff) | |
download | hakyll-015663657ceca7b168bf7d91fbc2fccc41c40904.tar.gz |
New resource module hierarchy
Diffstat (limited to 'src/Hakyll/Core/Resource')
-rw-r--r-- | src/Hakyll/Core/Resource/Provider.hs | 68 | ||||
-rw-r--r-- | src/Hakyll/Core/Resource/Provider/File.hs | 30 |
2 files changed, 98 insertions, 0 deletions
diff --git a/src/Hakyll/Core/Resource/Provider.hs b/src/Hakyll/Core/Resource/Provider.hs new file mode 100644 index 0000000..377b029 --- /dev/null +++ b/src/Hakyll/Core/Resource/Provider.hs @@ -0,0 +1,68 @@ +-- | This module provides an API for resource providers. Resource providers +-- allow Hakyll to get content from resources; the type of resource depends on +-- the concrete instance. +-- +-- A resource is represented by the 'Resource' type. This is basically just a +-- newtype wrapper around 'Identifier' -- but it has an important effect: it +-- guarantees that a resource with this identifier can be provided by one or +-- more resource providers. +-- +-- Therefore, it is not recommended to read files directly -- you should use the +-- provided 'Resource' methods. +-- +module Hakyll.Core.Resource.Provider + ( ResourceProvider (..) + , resourceExists + , resourceDigest + , resourceModified + ) where + +import Control.Monad ((<=<)) +import Data.Word (Word8) + +import qualified Data.ByteString.Lazy as LB +import OpenSSL.Digest.ByteString.Lazy (digest) +import OpenSSL.Digest (MessageDigest (MD5)) + +import Hakyll.Core.Identifier +import Hakyll.Core.Store +import Hakyll.Core.Resource + +-- | A value responsible for retrieving and listing resources +-- +data ResourceProvider = ResourceProvider + { -- | A list of all resources this provider is able to provide + resourceList :: [Resource] + , -- | Retrieve a certain resource as string + resourceString :: Resource -> IO String + , -- | Retrieve a certain resource as lazy bytestring + resourceLazyByteString :: Resource -> IO LB.ByteString + } + +-- | Check if a given identifier has a resource +-- +resourceExists :: ResourceProvider -> Identifier -> Bool +resourceExists provider = flip elem $ map unResource $ resourceList provider + +-- | Retrieve a digest for a given resource +-- +resourceDigest :: ResourceProvider -> Resource -> IO [Word8] +resourceDigest provider = digest MD5 <=< resourceLazyByteString provider + +-- | Check if a resource was modified +-- +resourceModified :: ResourceProvider -> Resource -> Store -> IO Bool +resourceModified provider resource store = do + -- Get the latest seen digest from the store + lastDigest <- storeGet store itemName $ unResource resource + -- Calculate the digest for the resource + newDigest <- resourceDigest provider resource + -- Check digests + if Just newDigest == lastDigest + -- All is fine, not modified + then return False + -- Resource modified; store new digest + else do storeSet store itemName (unResource resource) newDigest + return True + where + itemName = "Hakyll.Core.ResourceProvider.resourceModified" diff --git a/src/Hakyll/Core/Resource/Provider/File.hs b/src/Hakyll/Core/Resource/Provider/File.hs new file mode 100644 index 0000000..a795fac --- /dev/null +++ b/src/Hakyll/Core/Resource/Provider/File.hs @@ -0,0 +1,30 @@ +-- | A concrete 'ResourceProvider' that gets it's resources from the filesystem +-- +module Hakyll.Core.Resource.Provider.File + ( fileResourceProvider + ) where + +import Control.Applicative ((<$>)) + +import qualified Data.ByteString.Lazy as LB + +import Hakyll.Core.Resource +import Hakyll.Core.Resource.Provider +import Hakyll.Core.Identifier +import Hakyll.Core.Util.File +import Hakyll.Core.Configuration + +-- | Create a filesystem-based 'ResourceProvider' +-- +fileResourceProvider :: HakyllConfiguration -> IO ResourceProvider +fileResourceProvider configuration = do + -- Retrieve a list of identifiers + list <- map parseIdentifier . filter (not . ignoreFile configuration) <$> + getRecursiveContents False "." + + -- Construct a resource provider + return ResourceProvider + { resourceList = map Resource list + , resourceString = readFile . toFilePath . unResource + , resourceLazyByteString = LB.readFile . toFilePath . unResource + } |