1 files changed, 31 insertions, 5 deletions
diff --git a/mako/pygen.py b/mako/pygen.py
index d6559e5..62967e3 100644
--- a/mako/pygen.py
+++ b/mako/pygen.py
@@ -37,10 +37,36 @@ class PythonPrinter(object):
 
         self._reset_multi_line_flags()
 
-    def write_blanks(self, num=1):
-        self.stream.write("\n" * num)
+        # marker for template source lines; this
+        # is part of source/template line mapping
+        self.last_source_line = -1
+
+        self.last_boilerplate_line = -1
+
+        # mapping of generated python lines to template
+        # source lines
+        self.source_map = {}
+
+        # list of "boilerplate" lines, these are lines
+        # that precede/follow a set of template source-mapped lines
+        self.boilerplate_map = []
+
+
+    def _update_lineno(self, num):
+        if self.last_boilerplate_line <= self.last_source_line:
+            self.boilerplate_map.append(self.lineno)
+            self.last_boilerplate_line = self.lineno
         self.lineno += num
 
+    def start_source(self, lineno):
+        if self.last_source_line != lineno:
+            self.source_map[self.lineno] = lineno
+            self.last_source_line = lineno
+
+    def write_blanks(self, num):
+        self.stream.write("\n" * num)
+        self._update_lineno(num)
+
     def write_indented_block(self, block):
         """print a line or lines of python which already contain indentation.
 
@@ -98,7 +124,7 @@ class PythonPrinter(object):
 
         # write the line
         self.stream.write(self._indent_line(line) + "\n")
-        self.lineno += 1
+        self._update_lineno(1)
 
         # see if this line should increase the indentation level.
         # note that a line can both decrase (before printing) and
@@ -218,13 +244,13 @@ class PythonPrinter(object):
         for entry in self.line_buffer:
             if self._in_multi_line(entry):
                 self.stream.write(entry + "\n")
-                self.lineno += 1
+                self._update_lineno(1)
             else:
                 entry = entry.expandtabs()
                 if stripspace is None and re.search(r"^[ \t]*[^# \t]", entry):
                     stripspace = re.match(r"^([ \t]*)", entry).group(1)
                 self.stream.write(self._indent_line(entry, stripspace) + "\n")
-                self.lineno += 1
+                self._update_lineno(1)
 
         self.line_buffer = []
         self._reset_multi_line_flags()