From: sof <unknown>
Date: Mon, 10 May 1999 16:55:43 +0000 (+0000)
Subject: [project @ 1999-05-10 16:55:43 by sof]
X-Git-Tag: Approximately_9120_patches~6234
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=d993f5b07a82df12aaba033f42925693ac524752;p=ghc-hetmet.git

[project @ 1999-05-10 16:55:43 by sof]
The implementation of hGetLine, as given in the report, doesn't handle
partial lines on unbuffered handles that well (not at all, as it turns
out). Fixed.
---

diff --git a/ghc/lib/std/IO.lhs b/ghc/lib/std/IO.lhs
index 6670ff3..5b5aef6 100644
--- a/ghc/lib/std/IO.lhs
+++ b/ghc/lib/std/IO.lhs
@@ -216,14 +216,34 @@ hGetChar handle =
      then return (chr intc)
      else constructErrorAndFail "hGetChar"
 
+{-
+  If EOF is reached before EOL is encountered, ignore the
+  EOF and return the partial line. Next attempt at calling
+  hGetLine on the handle will yield an EOF IO exception though.
+-}
 hGetLine :: Handle -> IO String
 hGetLine h = do
   c <- hGetChar h
-  if c == '\n' 
-   then return "" 
+  if c == '\n' then
+     return ""
    else do
-     s <- hGetLine h
-     return (c:s)
+    l <- getRest
+    return (c:l)
+ where
+  getRest = do
+    c <- 
+      catch 
+        (hGetChar h)
+        (\ err -> do
+          if isEOFError err then
+	     return '\n'
+	   else
+	     ioError err)
+    if c == '\n' then
+       return ""
+     else do
+       s <- getRest
+       return (c:s)
 
 \end{code}