From: Evgenii Akentev <i@ak3n.com>
Date: Sun, 9 Jul 2023 14:56:12 +0000 (+0400)
Subject: Fix goToLine when line number is negative
X-Git-Url: https://git.ak3n.com/?a=commitdiff_plain;h=166cd97553e918c5bdf67d38ab86dc1a9326d0da;p=line-indexed-cursor.git

Fix goToLine when line number is negative
---

diff --git a/src/System/IO/LineIndexedCursor.hs b/src/System/IO/LineIndexedCursor.hs
index 14d62cd..10e2819 100644
--- a/src/System/IO/LineIndexedCursor.hs
+++ b/src/System/IO/LineIndexedCursor.hs
@@ -83,8 +83,9 @@ getCurrentLineNumber' CursorHandle{..} = do
   pure cln
 
 goToLine' :: CursorHandle -> Integer -> IO Integer
-goToLine' CursorHandle{..} ln = do
-  modifyMVar linesIdx $ \(idx, size, _) -> do
+goToLine' ch@CursorHandle{..} ln =
+  if (ln < 0) then getCurrentLineNumber' ch
+  else modifyMVar linesIdx $ \(idx, size, _) -> do
     if ln > size then do
       hSeek fileHandle AbsoluteSeek (idx !! 0)
       -- try to read until the requested line number
diff --git a/test/Main.hs b/test/Main.hs
index 8e002ec..9e74031 100644
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -29,6 +29,13 @@ main = hspec $ do
         l <- getCurrentLine c
         l `shouldBe` Just "Sed elementum velit sit amet orci mollis tincidunt."
 
+      it "goToLine is negative" $ \(_, c) -> do
+        ln <- goToLine c (-10)
+        ln `shouldBe` 0
+
+        l <- getCurrentLine c
+        l `shouldBe` Just "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
+
       it "goToLine is too big" $ \(_, c) -> do
         l <- getCurrentLine c
         l `shouldBe` Just "Lorem ipsum dolor sit amet, consectetur adipiscing elit."