1 files changed, 56 insertions, 0 deletions

diff --git a/compiler/src/Caching.hs b/compiler/src/Caching.hs
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+++ b/compiler/src/Caching.hs
@@ -0,0 +1,56 @@
+-- ldgallery - A static generator which turns a collection of tagged
+--             pictures into a searchable web gallery.
+--
+-- Copyright (C) 2019-2020  Pacien TRAN-GIRARD
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU Affero General Public License for more details.
+--
+-- You should have received a copy of the GNU Affero General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+module Caching
+  ( Cache
+  , skipCache
+  , withCache
+  ) where
+
+
+import Control.Monad (when)
+import System.Directory (removePathForcibly, doesDirectoryExist, doesFileExist)
+
+import FileProcessors (FileProcessor)
+import Files
+
+
+type Cache = FileProcessor -> FileProcessor
+
+skipCache :: Cache
+skipCache processor inputPath outputPath =
+  removePathForcibly outputPath
+  >> processor inputPath outputPath
+
+withCache :: Cache
+withCache processor inputPath outputPath =
+  do
+    isDir <- doesDirectoryExist outputPath
+    when isDir $ removePathForcibly outputPath
+
+    fileExists <- doesFileExist outputPath
+    if fileExists then
+      do
+        needUpdate <- isOutdated True inputPath outputPath
+        if needUpdate then update else skip
+    else
+      update
+
+  where
+    update = processor inputPath outputPath
+    skip = putStrLn $ "Skipping:\t" ++ outputPath