From 108dc9c0d3acefb4597619ae7755cf2199e5d8b8 Mon Sep 17 00:00:00 2001
From: Gustavo Castellanos <gustavoaca1997@gmail.com>
Date: Thu, 3 Oct 2019 04:22:29 -0400
Subject: [PATCH 1/4] Fixes #144

---
 templates/wrappers.hs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/templates/wrappers.hs b/templates/wrappers.hs
index 4263a18..7214e38 100644
--- a/templates/wrappers.hs
+++ b/templates/wrappers.hs
@@ -179,7 +179,8 @@ data AlexState = AlexState {
         alex_inp :: ByteString.ByteString,      -- the current input
         alex_chr :: !Char,      -- the character before the input
 #endif /* ALEX_MONAD_BYTESTRING */
-        alex_scd :: !Int        -- the current startcode
+        alex_scd :: !Int,        -- the current startcode
+        alex_errs :: [String]   -- lexical errors so far
 #ifdef ALEX_MONAD_USER_STATE
       , alex_ust :: AlexUserState -- AlexUserState will be defined in the user program
 #endif
@@ -199,6 +200,7 @@ runAlex input__ (Alex f)
                         alex_pos = alexStartPos,
                         alex_inp = input__,
                         alex_chr = '\n',
+                        alex_errs = [],
 #ifdef ALEX_MONAD_USER_STATE
                         alex_ust = alexInitUserState,
 #endif
@@ -252,6 +254,15 @@ alexSetInput (pos,c,inp__,bpos)
 alexError :: String -> Alex a
 alexError message = Alex $ const $ Left message
 
+alexPushError :: String -> Alex ()
+alexPushError message = Alex $ \s@AlexState{alex_errs=errs} -> Right (s{ alex_errs=message:errs }, ())
+
+-- Use this function for returning all lexical errors that have occurred
+alexThrowErrors :: Alex ()
+alexThrowErrors = Alex $ \s@AlexState{alex_errs=errs} -> case errs of
+  [] -> Right (s, ())
+  _ -> Left $ concatMap (++ "\n") $ reverse errs
+
 alexGetStartCode :: Alex Int
 alexGetStartCode = Alex $ \s@AlexState{alex_scd=sc} -> Right (s, sc)
 
@@ -275,7 +286,10 @@ alexMonadScan = do
   sc <- alexGetStartCode
   case alexScan inp__ sc of
     AlexEOF -> alexEOF
-    AlexError ((AlexPn _ line column),_,_,_) -> alexError $ "lexical error at line " ++ (show line) ++ ", column " ++ (show column)
+    AlexError (p@(AlexPn _ line column),x,y,s) -> do
+      alexPushError $ "lexical error at line " ++ (show line) ++ ", column " ++ (show column)
+      alexSetInput (p, x, y, (tail s))
+      alexMonadScan
     AlexSkip  inp__' _len -> do
         alexSetInput inp__'
         alexMonadScan

From a14a6bf5b4f288dde23ff34f169b534e9816c289 Mon Sep 17 00:00:00 2001
From: Gustavo Castellanos <gustavoaca1997@gmail.com>
Date: Thu, 3 Oct 2019 04:44:12 -0400
Subject: [PATCH 2/4] Solve bug with ALEX_MONAD_BYTESTRING

---
 templates/wrappers.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/templates/wrappers.hs b/templates/wrappers.hs
index 7214e38..eb7a551 100644
--- a/templates/wrappers.hs
+++ b/templates/wrappers.hs
@@ -288,7 +288,11 @@ alexMonadScan = do
     AlexEOF -> alexEOF
     AlexError (p@(AlexPn _ line column),x,y,s) -> do
       alexPushError $ "lexical error at line " ++ (show line) ++ ", column " ++ (show column)
+#ifndef ALEX_MONAD_BYTESTRING
       alexSetInput (p, x, y, (tail s))
+#else
+      alexSetInput (p, x, y, s-n)
+#endif
       alexMonadScan
     AlexSkip  inp__' _len -> do
         alexSetInput inp__'

From fce6396e0d41f18cac47a25e010af4d2f09b00e8 Mon Sep 17 00:00:00 2001
From: Gustavo Castellanos <gustavoaca1997@gmail.com>
Date: Thu, 3 Oct 2019 05:17:14 -0400
Subject: [PATCH 3/4] Some fixes

---
 templates/wrappers.hs | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/templates/wrappers.hs b/templates/wrappers.hs
index eb7a551..0ae14e6 100644
--- a/templates/wrappers.hs
+++ b/templates/wrappers.hs
@@ -285,14 +285,28 @@ alexMonadScan = do
 #endif /* ALEX_MONAD_BYTESTRING */
   sc <- alexGetStartCode
   case alexScan inp__ sc of
-    AlexEOF -> alexEOF
+    AlexEOF -> do
+      alexThrowErrors
+      alexEOF
+
+#if defined(ALEX_BASIC)
+    AlexError (p@(AlexPn _ line column), x, s) -> do
+#elif !defined(ALEX_MONAD_BYTESTRING)
     AlexError (p@(AlexPn _ line column),x,y,s) -> do
+#else
+    AlexError (p@(AlexPn _ line column), x, s, y) -> do
+#endif
+
       alexPushError $ "lexical error at line " ++ (show line) ++ ", column " ++ (show column)
-#ifndef ALEX_MONAD_BYTESTRING
-      alexSetInput (p, x, y, (tail s))
+
+#if defined(ALEX_BASIC)
+      alexSetInput (p, x, tail s)
+#elif !defined(ALEX_MONAD_BYTESTRING)
+      alexSetInput (p, x, y, tail s)
 #else
-      alexSetInput (p, x, y, s-n)
+      alexSetInput (p, x, ByteString.tail s, y)
 #endif
+
       alexMonadScan
     AlexSkip  inp__' _len -> do
         alexSetInput inp__'

From 90e623115c6c1a8c4aa9035ca0c9af42a3f0cea0 Mon Sep 17 00:00:00 2001
From: Gustavo Castellanos <gustavoaca1997@gmail.com>
Date: Thu, 3 Oct 2019 05:33:15 -0400
Subject: [PATCH 4/4] Remove last '\n' in final error message

---
 templates/wrappers.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/templates/wrappers.hs b/templates/wrappers.hs
index 0ae14e6..d498074 100644
--- a/templates/wrappers.hs
+++ b/templates/wrappers.hs
@@ -261,7 +261,7 @@ alexPushError message = Alex $ \s@AlexState{alex_errs=errs} -> Right (s{ alex_er
 alexThrowErrors :: Alex ()
 alexThrowErrors = Alex $ \s@AlexState{alex_errs=errs} -> case errs of
   [] -> Right (s, ())
-  _ -> Left $ concatMap (++ "\n") $ reverse errs
+  _ -> Left $ init $ concatMap (++ "\n") $ reverse errs
 
 alexGetStartCode :: Alex Int
 alexGetStartCode = Alex $ \s@AlexState{alex_scd=sc} -> Right (s, sc)