fix: escape characters as octal sequences

golden/data.qbe

@@ -1,3 +1,3 @@
 export
 data $d = align 8
-{z 16, b $g + 32 "foo\nbar\NULbaz" -1}
+{z 16, b $g + 32 "foo\012bar\000baz" -1}

src/Language/QBE.hs

@@ -85,17 +85,21 @@ import Data.Text (Text)
 import Data.Text.Short (ShortText)
 import qualified Data.Text.Short as TS
 import Data.ByteString (ByteString)
+import qualified Data.ByteString as BS
+import Data.ByteString.Internal (w2c)
 import Data.Word (Word64)
 import Data.List.NonEmpty (NonEmpty, toList)
 import Data.Maybe (maybeToList)
 import Prettyprinter
   ( Pretty(pretty), Doc, (<+>), vsep, hsep, hang, punctuate, group, flatAlt
-  , space, encloseSep, tupled, comma, equals, braces, lbrace, rbrace )
+  , space, encloseSep, tupled, comma, equals, braces, lbrace, rbrace, enclose )
 -- Instances
 import Data.Hashable (Hashable)
 import Control.DeepSeq (NFData)
 import Data.String (IsString)
 import Data.Data (Data)
+import Numeric (showOct)
+import Data.Char (isPrint, isAscii)
 
 -- * Identifiers
 ----------------
@@ -262,7 +266,17 @@ data DataItem
 instance Pretty DataItem where
   pretty (Symbol ident alignment) =
     hsep $ pretty ident : maybeToList ((pretty '+' <+>) . pretty <$> alignment)
-  pretty (String bs) = pretty $ show bs -- HACK: hoping that the escape sequences are the same...
+  -- ~~HACK: hoping that the escape sequences are the same...~~
+  -- ↑ wrong bitch (it's undocumented; i don't blame you babe.)
+  pretty (String bs) =
+    enclose "\"" "\"" . pretty . showHexSequences . BS.unpack $ bs
+    where
+      showHexSequences =
+        foldr (\a acc -> char a <> acc) ""
+      char c
+        | isAscii (w2c c) && isPrint (w2c c) = [w2c c]
+        | otherwise = "\\" <> pad 3 (showOct c "")
+      pad n s = replicate (max 0 (n - length s)) '0' <> s
   pretty (Const c) = pretty c
 
 data Field

test/Main.hs

@@ -6,8 +6,9 @@ module Main (main) where
 
 import Language.QBE
 
-import Test.Tasty (TestTree, defaultMain, testGroup)
+import Test.Tasty (TestTree, testGroup)
 import Test.Tasty.Silver (goldenVsAction)
+import Test.Tasty.Silver.Interactive (defaultMain)
 import System.FilePath ((</>), (<.>))
 import Prettyprinter (Pretty(pretty), layoutPretty, defaultLayoutOptions)
 import Prettyprinter.Render.Text (renderStrict)