Detect runaway indentations and go back to first column instead of going crazy.

Even though the resulting statement is not correctly formatted, it's
much more usable than before.

2 files changed, 10 insertions, 1 deletions

diff --git a/CHANGES b/CHANGES
index ff2753b..aa94dbd 100644
--- a/CHANGES
+++ b/CHANGES
@@ -15,6 +15,9 @@ Enhancements
    statements in certain encodings more reliable (issue20).
  * Improve parsing speed when SQL contains CLOBs or BLOBs (issue86).
  * Improve formatting of ORDER BY clauses (issue89).
+ * Formatter now tries to detect runaway indentations caused by
+   parsing errors or invalid SQL statements. When re-indenting such
+   statements the formatter flips back to column 0 before going crazy.
 
 Other
  * Documentation updates.
diff --git a/sqlparse/filters.py b/sqlparse/filters.py
index e238f69..fdb32ac 100644
--- a/sqlparse/filters.py
+++ b/sqlparse/filters.py
@@ -261,7 +261,13 @@ class ReindentFilter:
 
     def nl(self):
         # TODO: newline character should be configurable
-        ws = '\n' + (self.char * ((self.indent * self.width) + self.offset))
+        space = (self.char * ((self.indent * self.width) + self.offset))
+        # Detect runaway indenting due to parsing errors
+        if len(space) > 200:
+            # something seems to be wrong, flip back
+            self.indent = self.offset = 0
+            space = (self.char * ((self.indent * self.width) + self.offset))
+        ws = '\n' + space
         return sql.Token(T.Whitespace, ws)
 
     def _split_kwds(self, tlist):