[project @ 1999-04-13 15:46:49 by sof]

[ghc-hetmet.git] / ghc / compiler / basicTypes / SrcLoc.lhs

diff --git a/ghc/compiler/basicTypes/SrcLoc.lhs b/ghc/compiler/basicTypes/SrcLoc.lhs
index f051eef..5ebb9e6 100644 (file)
--- a/ghc/compiler/basicTypes/SrcLoc.lhs
+++ b/ghc/compiler/basicTypes/SrcLoc.lhs
@@ -1,5 +1,5 @@
 %
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
 %************************************************************************
 %*                                                                     *
@@ -28,9 +28,10 @@ module SrcLoc (
 
 #include "HsVersions.h"
 
+import Util            ( thenCmp )
 import Outputable
 import FastString      ( unpackFS )
-import GlaExts         ( Int(..), Int#, (+#) )
+import GlaExts         ( Int(..), (+#) )
 \end{code}
 
 %************************************************************************
@@ -89,6 +90,29 @@ incSrcLine loc       = loc
 %************************************************************************
 
 \begin{code}
+-- SrcLoc is an instance of Ord so that we can sort error messages easily
+instance Eq SrcLoc where
+  loc1 == loc2 = case loc1 `cmpSrcLoc` loc2 of
+                  EQ    -> True
+                  other -> False
+
+instance Ord SrcLoc where
+  compare = cmpSrcLoc
+
+cmpSrcLoc NoSrcLoc NoSrcLoc = EQ
+cmpSrcLoc NoSrcLoc other    = LT
+
+cmpSrcLoc (UnhelpfulSrcLoc s1) (UnhelpfulSrcLoc s2) = s1 `compare` s2
+cmpSrcLoc (UnhelpfulSrcLoc s1) other               = GT
+
+cmpSrcLoc (SrcLoc s1 l1) NoSrcLoc           = GT
+cmpSrcLoc (SrcLoc s1 l1) (UnhelpfulSrcLoc _) = LT
+cmpSrcLoc (SrcLoc s1 l1) (SrcLoc s2 l2)      = (s1 `compare` s2) `thenCmp` (l1 `cmpline` l2)
+                                            where
+                                               l1 `cmpline` l2 | l1 <#  l2 = LT
+                                                               | l1 ==# l2 = EQ
+                                                               | otherwise = GT 
+                                         
 instance Outputable SrcLoc where
     ppr (SrcLoc src_path src_line)
       = getPprStyle $ \ sty ->