1 files changed, 64 insertions, 0 deletions
diff --git a/src/HStyle/Block.hs b/src/HStyle/Block.hs
new file mode 100644
index 0000000..2fe38a2
--- /dev/null
+++ b/src/HStyle/Block.hs
@@ -0,0 +1,64 @@
+-- | A block of code
+{-# LANGUAGE OverloadedStrings #-}
+module HStyle.Block
+    ( Block
+    , fromText
+    , prettyBlock
+    , toLines
+    , subBlock
+    , perLine
+    , absoluteLineNumber
+    ) where
+
+import Data.Text (Text)
+import Data.Vector (Vector)
+import qualified Data.Vector as V
+import qualified Data.Text as T
+
+data Block = Block
+    { blockOffset :: Int
+    , blockLines  :: Vector Text
+    } deriving (Show)
+
+fromText :: Text -> Block
+fromText text = Block
+    { blockOffset = 0
+    , blockLines  = V.fromList $ T.lines text
+    }
+
+prettyBlock :: Int -> Block -> Text
+prettyBlock indent block = T.unlines $
+    map ((T.replicate indent " " `T.append`) . pretty) $
+    zip [offset + 1 ..] $ V.toList lines'
+  where
+    offset = blockOffset block
+    lines' = blockLines block
+    width  = length $ show (offset + V.length lines')
+
+    pretty (ln, t) =
+        let ln' = T.pack (show ln)
+            lnl = T.length ln'
+        in T.replicate (width - lnl) " " `T.append`
+            ln' `T.append` " " `T.append` t
+
+toLines :: Block -> [Text]
+toLines = V.toList . blockLines
+
+-- | Subblock from start to end -- including both.
+subBlock :: Int -> Int -> Block -> Block
+subBlock start end block = Block
+    { blockOffset = blockOffset block + start - 1
+    , blockLines  = V.slice (start - 1) (end - start + 1) $ blockLines block
+    }
+
+-- | Create a new block for every line.
+perLine :: Block -> [Block]
+perLine (Block offset lines')  = map line $
+    zip [offset + 0 ..] $ V.toList lines'
+  where
+    line (i, t) = Block i $ V.singleton t
+
+-- | Convert relative line number (within this block, 1-based) to an absolute
+-- line number
+absoluteLineNumber :: Int -> Block -> Int
+absoluteLineNumber i = (+ i) . blockOffset