Add SourceSpan module

semantic-diff.cabal

@@ -40,6 +40,7 @@ library
                      , Renderer.Summary
                      , SES
                      , Source
+                     , SourceSpan
                      , SplitDiff
                      , Syntax
                      , Term

src/Info.hs

@@ -5,11 +5,18 @@ import Data.Record
 import Prologue
 import Category
 import Range
+import SourceSpan
 import Test.QuickCheck
 
 newtype Cost = Cost { unCost :: Integer }
   deriving (Eq, Num, Ord, Show)
 
+sourceSpan :: HasField fields SourceSpan => Record fields -> SourceSpan
+sourceSpan = getField
+
+setSourceSpan :: HasField fields SourceSpan => Record fields -> SourceSpan -> Record fields
+setSourceSpan = setField
+
 characterRange :: HasField fields Range => Record fields -> Range
 characterRange = getField
 

src/SourceSpan.hs

@@ -0,0 +1,71 @@
+-- |
+-- Source position and span information
+--
+module SourceSpan where
+
+import Prologue
+import Data.Aeson ((.=), (.:))
+import qualified Data.Aeson as A
+
+-- |
+-- Source position information
+--
+data SourcePos = SourcePos
+  { -- |
+    -- Line number
+    --
+    line :: !Int
+    -- |
+    -- Column number
+    --
+  , column :: !Int
+  } deriving (Show, Read, Eq, Ord)
+
+displaySourcePos :: SourcePos -> Text
+displaySourcePos sp =
+  "line " <> show (line sp) <> ", column " <> show (column sp)
+
+instance A.ToJSON SourcePos where
+  toJSON SourcePos{..} =
+    A.toJSON [line, column]
+
+instance A.FromJSON SourcePos where
+  parseJSON arr = do
+    [line, col] <- A.parseJSON arr
+    pure $ SourcePos line col
+
+data SourceSpan = SourceSpan
+  { -- |
+    -- Source name
+    --
+    spanName :: !Text
+    -- |
+    -- Start of the span
+    --
+  , spanStart :: !SourcePos
+    -- End of the span
+    --
+  , spanEnd :: !SourcePos
+  } deriving (Show, Read, Eq, Ord)
+
+displayStartEndPos :: SourceSpan -> Text
+displayStartEndPos sp =
+  displaySourcePos (spanStart sp) <> " - " <> displaySourcePos (spanEnd sp)
+
+displaySourceSpan :: SourceSpan -> Text
+displaySourceSpan sp =
+  spanName sp <> " " <> displayStartEndPos sp
+
+instance A.ToJSON SourceSpan where
+  toJSON SourceSpan{..} =
+    A.object [ "name"  .= spanName
+             , "start" .= spanStart
+             , "end"   .= spanEnd
+             ]
+
+instance A.FromJSON SourceSpan where
+  parseJSON = A.withObject "SourceSpan" $ \o ->
+    SourceSpan     <$>
+      o .: "name"  <*>
+      o .: "start" <*>
+      o .: "end"