From f4ed6b5a85346e0add561fa5b8af9649e8a1a7df Mon Sep 17 00:00:00 2001
From: Sascha Brawer <sascha@brawer.ch>
Date: Sat, 1 Aug 2015 10:24:44 +0200
Subject: [PATCH] Make pretty error messages for LexerError

---
 Lib/fontTools/feaLib/lexer.py      |  8 ++++++++
 Lib/fontTools/feaLib/lexer_test.py | 10 ++++++++++
 2 files changed, 18 insertions(+)

diff --git a/Lib/fontTools/feaLib/lexer.py b/Lib/fontTools/feaLib/lexer.py
index d38210ff5..b544378eb 100644
--- a/Lib/fontTools/feaLib/lexer.py
+++ b/Lib/fontTools/feaLib/lexer.py
@@ -9,6 +9,14 @@ class LexerError(Exception):
         Exception.__init__(self, message)
         self.location = location
 
+    def __str__(self):
+        message = Exception.__str__(self)
+        if self.location:
+            path, line, column = self.location
+            return "%s:%d:%d: %s" % (path, line, column, message)
+        else:
+            return message
+
 
 class Lexer(object):
     NUMBER = "NUMBER"
diff --git a/Lib/fontTools/feaLib/lexer_test.py b/Lib/fontTools/feaLib/lexer_test.py
index 6c095fc1f..6fa3d42f0 100644
--- a/Lib/fontTools/feaLib/lexer_test.py
+++ b/Lib/fontTools/feaLib/lexer_test.py
@@ -9,6 +9,16 @@ def lex(s):
     return [(typ, tok) for (typ, tok, _) in Lexer(s, "test.fea")]
 
 
+class LexerErrorTest(unittest.TestCase):
+    def test_str(self):
+        err = LexerError("Squeak!", ("foo.fea", 23, 42))
+        self.assertEqual(str(err), "foo.fea:23:42: Squeak!")
+
+    def test_str_nolocation(self):
+        err = LexerError("Squeak!", None)
+        self.assertEqual(str(err), "Squeak!")
+
+
 class LexerTest(unittest.TestCase):
     def test_empty(self):
         self.assertEqual(lex(""), [])