1 files changed, 29 insertions, 1 deletions
diff --git a/Lib/sre_constants.py b/Lib/sre_constants.py
index 7480bf3ae0..bdea5e42b4 100644
--- a/Lib/sre_constants.py
+++ b/Lib/sre_constants.py
@@ -21,7 +21,35 @@ from _sre import MAXREPEAT, MAXGROUPS
 # should this really be here?
 
 class error(Exception):
-    pass
+    def __init__(self, msg, pattern=None, pos=None):
+        self.msg = msg
+        self.pattern = pattern
+        self.pos = pos
+        if pattern is not None and pos is not None:
+            msg = '%s at position %d' % (msg, pos)
+            if isinstance(pattern, str):
+                newline = '\n'
+            else:
+                newline = b'\n'
+            self.lineno = pattern.count(newline, 0, pos) + 1
+            self.colno = pos - pattern.rfind(newline, 0, pos)
+            if newline in pattern:
+                msg = '%s (line %d, column %d)' % (msg, self.lineno, self.colno)
+        else:
+            self.lineno = self.colno = None
+        super().__init__(msg)
+
+def linecol(doc, pos):
+    if isinstance(pattern, str):
+        newline = '\n'
+    else:
+        newline = b'\n'
+    lineno = pattern.count(newline, 0, pos) + 1
+    if lineno == 1:
+        colno = pos + 1
+    else:
+        colno = pos - doc.rindex(newline, 0, pos)
+    return lineno, colno
 
 
 class _NamedIntConstant(int):