diff --git a/src/configobj/__init__.py b/src/configobj/__init__.py
index 3f6eac0..a5c0840 100644
--- a/src/configobj/__init__.py
+++ b/src/configobj/__init__.py
@@ -472,6 +472,7 @@ def _initialise(self):
         self.default_values = {}
         self.extra_values = []
         self._created = False
+        self.source_map = {}
 
 
     def _interpolate(self, key, value):
@@ -514,7 +515,7 @@ def _check(entry):
         return val
 
 
-    def __setitem__(self, key, value, unrepr=False):
+    def __setitem__(self, key, value, unrepr=False, line_range=None):
         """
         Correctly set a value.
 
@@ -571,7 +572,8 @@ def __setitem__(self, key, value, unrepr=False):
                 else:
                     raise TypeError('Value is not a string "%s".' % value)
             dict.__setitem__(self, key, value)
-
+            if line_range:
+                self.source_map[key]=line_range
 
     def __delitem__(self, key):
         """Remove items from the sequence when deleting."""
@@ -582,6 +584,7 @@ def __delitem__(self, key):
             self.sections.remove(key)
         del self.comments[key]
         del self.inline_comments[key]
+        del self.source_map[key]
 
 
     def get(self, key, default=None):
@@ -1031,6 +1034,14 @@ def _get_triple_quote(value):
     return tsquot if "'''" in value else tdquot
 
 
+def _get_triple_quote(value):
+    """Helper for triple-quoting round-trips."""
+    if ('"""' in value) and ("'''" in value):
+        raise ConfigObjError('Value cannot be safely quoted: {0!r}'.format(value))
+
+    return tsquot if "'''" in value else tdquot
+
+
 class ConfigObj(Section):
     """An object to read, create, and write config files."""
 
@@ -1599,6 +1610,7 @@ def _parse(self, infile):
             # it's not a section marker,
             # so it should be a valid ``key = value`` line
             mat = self._keyword.match(line)
+            start_line=cur_index
             if mat is None:
                 self._handle_error(
                     'Invalid line ({0!r}) (matched as neither section nor keyword)'.format(line),
@@ -1662,7 +1674,7 @@ def _parse(self, infile):
                 # add the key.
                 # we set unrepr because if we have got this far we will never
                 # be creating a new section
-                this_section.__setitem__(key, value, unrepr=True)
+                this_section.__setitem__(key, value, unrepr=True, line_range=(start_line, cur_index))
                 this_section.inline_comments[key] = comment
                 this_section.comments[key] = comment_list
                 continue
@@ -2448,3 +2460,4 @@ def get_extra_values(conf, _prepend=()):
 
 
 """*A programming language is a medium of expression.* - Paul Graham"""
+ium of expression.* - Paul Graham"""