Add new lexer primitive to parse hexadecimal numbers

src/Copar/Parser/Lexer.hs

@@ -23,6 +23,7 @@ module Copar.Parser.Lexer
   , signed
   , adouble
   , complex
+  , hex
   ) where
 
 import           Data.Char
@@ -182,3 +183,10 @@ complex inner =
     optionalNum = fmap (fromMaybe 0) . optional
     sumOf p1 p2 = (,) <$> signed p1 <*> optionalNum (mandatorySigned p2)
 {-# INLINE complex #-}
+
+
+-- | Parse a hexadecimal number consisting of the prefix "0x" followed by
+-- hexadecimal digits (both upper and lower case).
+hex :: (MonadParser m, Integral a) => m a
+hex = lexeme (string "0x" *> L.hexadecimal)
+{-# INLINE hex #-}

tests/Copar/Parser/LexerSpec.hs

@@ -13,6 +13,7 @@ spec :: Spec
 spec = do
   spaceSpec
   complexSpec
+  hexSpec
 
 spaceSpec :: Spec
 spaceSpec = describe "whitespace" $ do
@@ -128,3 +129,19 @@ complexSpec = describe "complex" $ do
 
     it "parses a sum without whitespace" $
       p "-8.5-8.5i" `shouldParse` ((-8.5) :+ (-8.5))
+
+hexSpec :: Spec
+hexSpec = describe "hex" $ do
+  let p = parse (L.hex <* eof) ""
+
+  it "parses uppercase digits" $
+    p "0xDEADBEEF" `shouldParse` (0xdeadbeef :: Word)
+
+  it "parses lowercase digits" $
+    p "0xdeadbeef" `shouldParse` (0xdeadbeef :: Word)
+
+  it "parses mixed digits" $
+    p "0xdeadBEEF" `shouldParse` (0xdeadbeef :: Word)
+
+  it "required the 0x prefix" $
+    p `shouldFailOn` "deadbeef"