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--------------------------------------------------------------------------------
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Hakyll.Core.Compiler
( Compiler
, getUnderlying
, getUnderlyingExtension
, makeItem
, getRoute
, getResourceBody
, getResourceString
, getResourceLBS
, getResourceFilePath
, Internal.Snapshot
, saveSnapshot
, Internal.load
, Internal.loadSnapshot
, Internal.loadBody
, Internal.loadSnapshotBody
, Internal.loadAll
, Internal.loadAllSnapshots
, cached
, unsafeCompiler
, debugCompiler
, noResult
, withErrorMessage
) where
--------------------------------------------------------------------------------
import Control.Monad (unless, when, (>=>))
import Data.Binary (Binary)
import Data.ByteString.Lazy (ByteString)
import qualified Data.List.NonEmpty as NonEmpty
import Data.Typeable (Typeable)
import System.Environment (getProgName)
import System.FilePath (takeExtension)
--------------------------------------------------------------------------------
import Hakyll.Core.Compiler.Internal
import qualified Hakyll.Core.Compiler.Require as Internal
import Hakyll.Core.Dependencies
import Hakyll.Core.Identifier
import Hakyll.Core.Item
import Hakyll.Core.Logger as Logger
import Hakyll.Core.Provider
import Hakyll.Core.Routes
import qualified Hakyll.Core.Store as Store
--------------------------------------------------------------------------------
-- | Get the underlying identifier.
getUnderlying :: Compiler Identifier
getUnderlying = compilerUnderlying <$> compilerAsk
--------------------------------------------------------------------------------
-- | Get the extension of the underlying identifier. Returns something like
-- @".html"@
getUnderlyingExtension :: Compiler String
getUnderlyingExtension = takeExtension . toFilePath <$> getUnderlying
--------------------------------------------------------------------------------
-- | Create an item from the underlying identifier and a given value.
makeItem :: a -> Compiler (Item a)
makeItem x = do
identifier <- getUnderlying
return $ Item identifier x
--------------------------------------------------------------------------------
-- | Get the route for a specified item
getRoute :: Identifier -> Compiler (Maybe FilePath)
getRoute identifier = do
provider <- compilerProvider <$> compilerAsk
routes <- compilerRoutes <$> compilerAsk
-- Note that this makes us dependend on that identifier: when the metadata
-- of that item changes, the route may change, hence we have to recompile
(mfp, um) <- compilerUnsafeIO $ runRoutes routes provider identifier
when um $ compilerTellDependencies [IdentifierDependency identifier]
return mfp
--------------------------------------------------------------------------------
-- | Get the full contents of the matched source file as a string,
-- but without metadata preamble, if there was one.
getResourceBody :: Compiler (Item String)
getResourceBody = getResourceWith resourceBody
--------------------------------------------------------------------------------
-- | Get the full contents of the matched source file as a string.
getResourceString :: Compiler (Item String)
getResourceString = getResourceWith resourceString
--------------------------------------------------------------------------------
-- | Get the full contents of the matched source file as a lazy bytestring.
getResourceLBS :: Compiler (Item ByteString)
getResourceLBS = getResourceWith resourceLBS
--------------------------------------------------------------------------------
-- | Get the file path of the resource we are compiling
getResourceFilePath :: Compiler FilePath
getResourceFilePath = do
provider <- compilerProvider <$> compilerAsk
id' <- compilerUnderlying <$> compilerAsk
return $ resourceFilePath provider id'
--------------------------------------------------------------------------------
-- | Overloadable function for 'getResourceString' and 'getResourceLBS'
getResourceWith :: (Provider -> Identifier -> IO a) -> Compiler (Item a)
getResourceWith reader = do
provider <- compilerProvider <$> compilerAsk
id' <- compilerUnderlying <$> compilerAsk
let filePath = toFilePath id'
if resourceExists provider id'
then compilerUnsafeIO $ Item id' <$> reader provider id'
else fail $ error' filePath
where
error' fp = "Hakyll.Core.Compiler.getResourceWith: resource " ++
show fp ++ " not found"
--------------------------------------------------------------------------------
-- | Save a snapshot of the item. This function returns the same item, which
-- convenient for building '>>=' chains.
saveSnapshot :: (Binary a, Typeable a)
=> Internal.Snapshot -> Item a -> Compiler (Item a)
saveSnapshot snapshot item = do
store <- compilerStore <$> compilerAsk
logger <- compilerLogger <$> compilerAsk
compilerUnsafeIO $ do
Logger.debug logger $ "Storing snapshot: " ++ snapshot
Internal.saveSnapshot store snapshot item
-- Signal that we saved the snapshot.
Compiler $ \_ -> return $ CompilerSnapshot snapshot (return item)
--------------------------------------------------------------------------------
-- | Turn on caching for a compilation value to avoid recomputing it
-- on subsequent Hakyll runs.
-- The storage key consists of the underlying identifier of the compiled
-- ressource and the given name.
cached :: (Binary a, Typeable a)
=> String
-> Compiler a
-> Compiler a
cached name compiler = do
id' <- compilerUnderlying <$> compilerAsk
store <- compilerStore <$> compilerAsk
provider <- compilerProvider <$> compilerAsk
-- Give a better error message when the resource is not there at all.
unless (resourceExists provider id') $ fail $ itDoesntEvenExist id'
let modified = resourceModified provider id'
if modified
then do
x <- compiler
compilerUnsafeIO $ Store.set store [name, show id'] x
return x
else do
compilerTellCacheHits 1
x <- compilerUnsafeIO $ Store.get store [name, show id']
progName <- compilerUnsafeIO getProgName
case x of Store.Found x' -> return x'
_ -> fail $ error' progName
where
error' progName =
"Hakyll.Core.Compiler.cached: Cache corrupt! " ++
"Try running: " ++ progName ++ " clean"
itDoesntEvenExist id' =
"Hakyll.Core.Compiler.cached: You are trying to (perhaps " ++
"indirectly) use `cached` on a non-existing resource: there " ++
"is no file backing " ++ show id'
--------------------------------------------------------------------------------
-- | Run an IO computation without dependencies in a Compiler
unsafeCompiler :: IO a -> Compiler a
unsafeCompiler = compilerUnsafeIO
--------------------------------------------------------------------------------
-- | Fail so that it is treated as non-defined in an @\$if()\$@ branching
-- "Hakyll.Web.Template" macro, and alternative
-- 'Hakyll.Web.Template.Context.Context's are tried
--
-- @since 4.13.0
noResult :: String -> Compiler a
noResult = compilerNoResult . return
--------------------------------------------------------------------------------
-- | Prepend an error line to the error, if there is one. This allows you to
-- add helpful context to error messages.
--
-- @since 4.13.0
withErrorMessage :: String -> Compiler a -> Compiler a
withErrorMessage x = do
compilerTry >=> either (compilerResult . CompilerError . prepend) return
where
prepend (CompilationFailure es) = CompilationFailure (x `NonEmpty.cons` es)
prepend (CompilationNoResult es) = CompilationNoResult (x : es)
--------------------------------------------------------------------------------
-- | Compiler for debugging purposes.
-- Passes a message to the debug logger that is printed in verbose mode.
debugCompiler :: String -> Compiler ()
debugCompiler msg = do
logger <- compilerLogger <$> compilerAsk
compilerUnsafeIO $ Logger.debug logger msg
|
