Merge branch 'master' into forward-compatible-rendering

src/Renderer/Patch.hs

@@ -1,6 +1,7 @@
 module Renderer.Patch (
   patch,
-  hunks
+  hunks,
+  Hunk(..)
 ) where
 
 import Alignment
@@ -76,16 +77,19 @@ getRange (Pure patch) = let Info range _ :< _ = getSplitTerm patch in range
 
 -- | Returns the header given two source blobs and a hunk.
 header :: Both SourceBlob -> Hunk a -> String
-header blobs hunk = "diff --git a/" ++ pathA ++ " b/" ++ pathB ++ "\n" ++
-  "index " ++ oidA ++ ".." ++ oidB ++ "\n" ++
-  "@@ -" ++ show offsetA ++ "," ++ show lengthA ++ " +" ++ show offsetB ++ "," ++ show lengthB ++ " @@\n"
-  where (lengthA, lengthB) = runBoth . fmap getSum $ hunkLength hunk
-        (offsetA, offsetB) = runBoth . fmap getSum $ offset hunk
-        (pathA, pathB) = runBoth $ path <$> blobs
-        (oidA, oidB) = runBoth $ oid <$> blobs
+header blobs hunk = filepathHeader ++ blobOidHeader ++ maybeOffsetHeader
+   where filepathHeader = "diff --git a/" ++ pathA ++ " b/" ++ pathB ++ "\n"
+         blobOidHeader = "index " ++ oidA ++ ".." ++ oidB ++ "\n"
+         maybeOffsetHeader = if lengthA > 0 && lengthB > 0 then offsetHeader else mempty
+         offsetHeader = "@@ -" ++ show offsetA ++ "," ++ show lengthA ++ " +" ++ show offsetB ++ "," ++ show lengthB ++ " @@\n"
+         (lengthA, lengthB) = runBoth . fmap getSum $ hunkLength hunk
+         (offsetA, offsetB) = runBoth . fmap getSum $ offset hunk
+         (pathA, pathB) = runBoth $ path <$> blobs
+         (oidA, oidB) = runBoth $ oid <$> blobs
 
 -- | Render a diff as a series of hunks.
 hunks :: Renderer a [Hunk (SplitDiff a Info)]
+hunks diff blobs | Both (True, True) <- Source.null . source <$> blobs = [Hunk { offset = mempty, changes = [], trailingContext = [] }]
 hunks diff blobs = hunksInRows (Both (1, 1)) . Prelude.fst $ splitDiffByLines diff (pure 0) (source <$> blobs)
 
 -- | Given beginning line numbers, turn rows in a split diff into hunks in a

src/Source.hs

@@ -5,6 +5,7 @@ import qualified Data.Vector as Vector
 import qualified Data.Text as T
 
 data SourceBlob = SourceBlob { source :: Source Char, oid :: String, path :: FilePath }
+  deriving (Show, Eq)
 
 -- | The contents of a source file, backed by a vector for efficient slicing.
 newtype Source a = Source { getVector :: Vector.Vector a  }

test/PatchOutputSpec.hs

@@ -12,5 +12,5 @@ import Test.Hspec
 spec :: Spec
 spec = parallel $
   describe "hunks" $
-    it "empty diffs have no hunks" $
-      hunks (Free . Annotated (pure (Info (Range 0 0) mempty)) $ Leaf "") (Both (SourceBlob (fromList "") "abcde" "path2.txt", SourceBlob (fromList "") "xyz" "path2.txt")) `shouldBe` []
+    it "empty diffs have empty hunks" $
+        hunks (Free . Annotated (pure (Info (Range 0 0) mempty)) $ Leaf "") (Both (SourceBlob (fromList "") "abcde" "path2.txt", SourceBlob (fromList "") "xyz" "path2.txt")) `shouldBe` [Hunk {offset = Both (0, 0), changes = [], trailingContext = []}]