Fixes #187 - copying files from ext that do not exist. (#189)

waspc/src/ExternalCode.hs

@@ -7,8 +7,11 @@ module ExternalCode
     , SourceExternalCodeDir
     ) where
 
+import Control.Exception (catch)
+import System.IO.Error (isDoesNotExistError)
 import qualified Data.Text.Lazy as TextL
 import qualified Data.Text.Lazy.IO as TextL.IO
+import Data.Maybe (catMaybes)
 import Data.Text (Text)
 
 import qualified Util.IO
@@ -60,7 +63,14 @@ readFiles extCodeDirPath = do
     --     or create new file draft that will support that.
     --     In generator, when creating TextFileDraft, give it function/logic for text transformation,
     --     and it will be taken care of when draft will be written to the disk.
-    fileTexts <- mapM (TextL.IO.readFile . SP.toFilePath) absFilePaths
+    fileTexts <- catMaybes <$> mapM (tryReadFile . SP.toFilePath) absFilePaths
     let files = map (\(path, text) -> File path extCodeDirPath text) (zip relFilePaths fileTexts)
     return files
-
+    where
+        -- NOTE(matija): we had cases (e.g. tmp Vim files) where a file initially existed
+        -- but then got deleted before actual reading was invoked.
+        -- That would make this function crash, so we just ignore those errors.
+        tryReadFile :: FilePath -> IO (Maybe TextL.Text)
+        tryReadFile fp = (Just <$> (TextL.IO.readFile fp)) `catch` (\e -> if isDoesNotExistError e
+                                                                          then return Nothing
+                                                                          else ioError e)

waspc/src/Generator/FileDraft/WriteableMonad.hs

@@ -3,6 +3,8 @@ module Generator.FileDraft.WriteableMonad
        ) where
 
 
+import Control.Exception (catch)
+import System.IO.Error (isDoesNotExistError)
 import qualified System.Directory
 import qualified Data.Text.IO
 import Data.Aeson as Aeson
@@ -48,7 +50,16 @@ class (Monad m) => WriteableMonad m where
 
 instance WriteableMonad IO where
     createDirectoryIfMissing = System.Directory.createDirectoryIfMissing
-    copyFile = System.Directory.copyFile
+    -- TODO(matija): we should rename this function to make it clear it won't throw an exception when
+    -- a file does not exist.
+    copyFile src dst = do
+        -- NOTE(matija): we had cases (e.g. tmp Vim files) where a file initially existed
+        -- when the filedraft was created but then got deleted before actual copying was invoked.
+        -- That would make this function crash, so we just ignore those errors.
+        (System.Directory.copyFile src dst) `catch` (\e -> if isDoesNotExistError e
+                                                           then return ()
+                                                           else ioError e)
+
     writeFileFromText = Data.Text.IO.writeFile
     getTemplateFileAbsPath = Templates.getTemplateFileAbsPath
     getTemplatesDirAbsPath = Templates.getTemplatesDirAbsPath