Add UTF-16LE encoding

source/library/Witch/Encoding.hs

@@ -9,3 +9,6 @@ type ISO_8859_1 = Tagged.Tagged "ISO-8859-1"
 
 -- | <https://en.wikipedia.org/wiki/UTF-8>
 type UTF_8 = Tagged.Tagged "UTF-8"
+
+-- | <https://en.wikipedia.org/wiki/UTF-16>
+type UTF_16LE = Tagged.Tagged "UTF-16LE"

source/library/Witch/Instances.hs

@@ -31,6 +31,7 @@ import qualified Data.Set as Set
 import qualified Data.Tagged as Tagged
 import qualified Data.Text as Text
 import qualified Data.Text.Encoding as Text
+import qualified Data.Text.Encoding.Error as Text
 import qualified Data.Text.Lazy as LazyText
 import qualified Data.Text.Lazy.Encoding as LazyText
 import qualified Data.Time as Time
@@ -41,6 +42,7 @@ import qualified Data.Word as Word
 import qualified GHC.Float as Float
 import qualified Numeric
 import qualified Numeric.Natural as Natural
+import qualified System.IO.Unsafe as Unsafe
 import qualified Witch.Encoding as Encoding
 import qualified Witch.From as From
 import qualified Witch.TryFrom as TryFrom
@@ -1334,6 +1336,59 @@ instance From.From String (Encoding.UTF_8 ByteString.ByteString) where
 instance From.From String (Encoding.UTF_8 LazyByteString.ByteString) where
   from = Utility.via @LazyText.Text
 
+-- UTF-16LE
+
+-- | Uses 'Text.decodeUtf16LE'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE ByteString.ByteString) Text.Text where
+  tryFrom = Utility.eitherTryFrom $ todo @Text.UnicodeException . Text.decodeUtf16LE . From.from
+
+todo :: Exception.Exception e => a -> Either e a
+todo = Unsafe.unsafePerformIO . Exception.try . Exception.evaluate
+
+-- | Converts via 'Text.Text'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE ByteString.ByteString) LazyText.Text where
+  tryFrom = Utility.eitherTryFrom $ fmap (Utility.into @LazyText.Text) . Utility.tryInto @Text.Text
+
+-- | Converts via 'Text.Text'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE ByteString.ByteString) String where
+  tryFrom = Utility.eitherTryFrom $ fmap (Utility.into @String) . Utility.tryInto @Text.Text
+
+-- | Uses 'LazyText.decodeUtf16LE'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE LazyByteString.ByteString) LazyText.Text where
+  tryFrom = Utility.eitherTryFrom $ todo @Text.UnicodeException . LazyText.decodeUtf16LE . From.from
+
+-- | Converts via 'LazyText.Text'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE LazyByteString.ByteString) Text.Text where
+  tryFrom = Utility.eitherTryFrom $ fmap (Utility.into @Text.Text) . Utility.tryInto @LazyText.Text
+
+-- | Converts via 'LazyText.Text'.
+instance TryFrom.TryFrom (Encoding.UTF_16LE LazyByteString.ByteString) String where
+  tryFrom = Utility.eitherTryFrom $ fmap (Utility.into @String) . Utility.tryInto @LazyText.Text
+
+-- | Uses 'Text.encodeUtf16LE'.
+instance From.From Text.Text (Encoding.UTF_16LE ByteString.ByteString) where
+  from = From.from . Text.encodeUtf16LE
+
+-- | Converts via 'ByteString.ByteString'.
+instance From.From Text.Text (Encoding.UTF_16LE LazyByteString.ByteString) where
+  from = fmap From.from . Utility.into @(Encoding.UTF_16LE ByteString.ByteString)
+
+-- | Uses 'LazyText.encodeUtf16LE'.
+instance From.From LazyText.Text (Encoding.UTF_16LE LazyByteString.ByteString) where
+  from = From.from . LazyText.encodeUtf16LE
+
+-- | Converts via 'LazyByteString.ByteString'.
+instance From.From LazyText.Text (Encoding.UTF_16LE ByteString.ByteString) where
+  from = fmap From.from . Utility.into @(Encoding.UTF_16LE LazyByteString.ByteString)
+
+-- | Converts via 'Text.Text'.
+instance From.From String (Encoding.UTF_16LE ByteString.ByteString) where
+  from = Utility.via @Text.Text
+
+-- | Converts via 'LazyText.Text'.
+instance From.From String (Encoding.UTF_16LE LazyByteString.ByteString) where
+  from = Utility.via @LazyText.Text
+
 --
 
 realFloatToRational ::

source/test-suite/Main.hs

@@ -2162,6 +2162,75 @@ spec = describe "Witch" $ do
         f "" `shouldBe` Tagged.Tagged (LazyByteString.pack [])
         f "a" `shouldBe` Tagged.Tagged (LazyByteString.pack [0x61])
 
+    describe "TryFrom (UTF_16LE ByteString) Text" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE ByteString.ByteString) @Text.Text
+      it "works" $ do
+        f (Tagged.Tagged (ByteString.pack [])) `shouldBe` Just (Text.pack "")
+        f (Tagged.Tagged (ByteString.pack [0x24, 0x00])) `shouldBe` Just (Text.pack "\x24")
+        f (Tagged.Tagged (ByteString.pack [0xa3, 0x00])) `shouldBe` Just (Text.pack "\xa3")
+        f (Tagged.Tagged (ByteString.pack [0xac, 0x20])) `shouldBe` Just (Text.pack "\x20ac")
+        f (Tagged.Tagged (ByteString.pack [0x00, 0xd8, 0x48, 0xdf])) `shouldBe` Just (Text.pack "\x10348")
+        f (Tagged.Tagged (ByteString.pack [0x00])) `shouldBe` Nothing
+
+    describe "TryFrom (UTF_16LE ByteString) LazyText" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE ByteString.ByteString) @LazyText.Text
+      it "works" $ do
+        f (Tagged.Tagged (ByteString.pack [0x61, 0x00])) `shouldBe` Just (LazyText.pack "a")
+
+    describe "TryFrom (UTF_16LE ByteString) String" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE ByteString.ByteString) @String
+      it "works" $ do
+        f (Tagged.Tagged (ByteString.pack [0x61, 0x00])) `shouldBe` Just "a"
+
+    describe "TryFrom (UTF_16LE LazyByteString) LazyText" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE LazyByteString.ByteString) @LazyText.Text
+      it "works" $ do
+        f (Tagged.Tagged (LazyByteString.pack [0x61, 0x00])) `shouldBe` Just (LazyText.pack "a")
+
+    describe "TryFrom (UTF_16LE LazyByteString) Text" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE LazyByteString.ByteString) @Text.Text
+      it "works" $ do
+        f (Tagged.Tagged (LazyByteString.pack [0x61, 0x00])) `shouldBe` Just (Text.pack "a")
+
+    describe "TryFrom (UTF_16LE LazyByteString) String" $ do
+      let f = hush . Witch.tryFrom @(Encoding.UTF_16LE LazyByteString.ByteString) @String
+      it "works" $ do
+        f (Tagged.Tagged (LazyByteString.pack [0x61, 0x00])) `shouldBe` Just "a"
+
+    describe "From Text (UTF_16LE ByteString)" $ do
+      let f = Witch.from @Text.Text @(Encoding.UTF_16LE ByteString.ByteString)
+      it "works" $ do
+        f (Text.pack "") `shouldBe` Tagged.Tagged (ByteString.pack [])
+        f (Text.pack "\x24") `shouldBe` Tagged.Tagged (ByteString.pack [0x24, 0x00])
+        f (Text.pack "\xa3") `shouldBe` Tagged.Tagged (ByteString.pack [0xa3, 0x00])
+        f (Text.pack "\x20ac") `shouldBe` Tagged.Tagged (ByteString.pack [0xac, 0x20])
+        f (Text.pack "\x10348") `shouldBe` Tagged.Tagged (ByteString.pack [0x00, 0xd8, 0x48, 0xdf])
+
+    describe "From Text (UTF_16LE LazyByteString)" $ do
+      let f = Witch.from @Text.Text @(Encoding.UTF_16LE LazyByteString.ByteString)
+      it "works" $ do
+        f (Text.pack "a") `shouldBe` Tagged.Tagged (LazyByteString.pack [0x61, 0x00])
+
+    describe "From LazyText (UTF_16LE LazyByteString)" $ do
+      let f = Witch.from @LazyText.Text @(Encoding.UTF_16LE LazyByteString.ByteString)
+      it "works" $ do
+        f (LazyText.pack "a") `shouldBe` Tagged.Tagged (LazyByteString.pack [0x61, 0x00])
+
+    describe "From LazyText (UTF_16LE ByteString)" $ do
+      let f = Witch.from @LazyText.Text @(Encoding.UTF_16LE ByteString.ByteString)
+      it "works" $ do
+        f (LazyText.pack "a") `shouldBe` Tagged.Tagged (ByteString.pack [0x61, 0x00])
+
+    describe "From String (UTF_16LE ByteString)" $ do
+      let f = Witch.from @String @(Encoding.UTF_16LE ByteString.ByteString)
+      it "works" $ do
+        f "a" `shouldBe` Tagged.Tagged (ByteString.pack [0x61, 0x00])
+
+    describe "From String (UTF_16LE LazyByteString)" $ do
+      let f = Witch.from @String @(Encoding.UTF_16LE LazyByteString.ByteString)
+      it "works" $ do
+        f "a" `shouldBe` Tagged.Tagged (LazyByteString.pack [0x61, 0x00])
+
 newtype Age
   = Age Int.Int8
   deriving (Eq, Show)