Add limit=n args to extract_stack and extract_tb calls, to minimize scanning through full call stack - trying to address UnicodeDecodeError exceptions from loading in more code than we need.

git-svn-id: svn://svn.code.sf.net/p/pyparsing/code/trunk@415 9bf210a0-9d2d-494c-87cf-cfb32e7dff7b

3 files changed, 64 insertions, 7 deletions

diff --git a/src/CHANGES b/src/CHANGES
index 6971d81..b73b7bb 100644
--- a/src/CHANGES
+++ b/src/CHANGES
@@ -4,6 +4,11 @@ Change Log
 

 Version 2.1.8 - 

 ------------------------------

+- Fixed issue in the optimization to _trim_arity, when the full 

+  stacktrace is retrieved to determine if a TypeError is raised in

+  pyparsing or in the caller's parse action. Code was traversing

+  the full stacktrace, and potentially encountering UnicodeDecodeError.

+

 - Fixed bug in ParserElement.inlineLiteralsUsing, causing infinite 

   loop with Suppress.

 

diff --git a/src/pyparsing.py b/src/pyparsing.py
index e101ab4..9191426 100644
--- a/src/pyparsing.py
+++ b/src/pyparsing.py
@@ -58,7 +58,7 @@ The pyparsing module handles some of the problems that are typically vexing when
 """

 

 __version__ = "2.1.8"

-__versionTime__ = "11 Aug 2016 20:00 UTC"

+__versionTime__ = "12 Aug 2016 14:46 UTC"

 __author__ = "Paul McGuire <ptmcg@users.sourceforge.net>"

 

 import string

@@ -1017,13 +1017,13 @@ def _trim_arity(func, maxargs=2):
     

     # traceback return data structure changed in Py3.5 - normalize back to plain tuples

     if system_version[:2] >= (3,5):

-        def extract_stack():

+        def extract_stack(limit=0):

             # special handling for Python 3.5.0 - extra deep call stack by 1

             offset = -3 if system_version == (3,5,0) else -2

-            frame_summary = traceback.extract_stack()[offset]

+            frame_summary = traceback.extract_stack(limit=-offset+limit-1)[offset]

             return [(frame_summary.filename, frame_summary.lineno)]

-        def extract_tb(tb):

-            frames = traceback.extract_tb(tb)

+        def extract_tb(tb, limit=0):

+            frames = traceback.extract_tb(tb, limit=limit)

             frame_summary = frames[-1]

             return [(frame_summary.filename, frame_summary.lineno)]

     else:

@@ -1036,7 +1036,7 @@ def _trim_arity(func, maxargs=2):
     LINE_DIFF = 6

     # IF ANY CODE CHANGES, EVEN JUST COMMENTS OR BLANK LINES, BETWEEN THE NEXT LINE AND 

     # THE CALL TO FUNC INSIDE WRAPPER, LINE_DIFF MUST BE MODIFIED!!!!

-    this_line = extract_stack()[-1]

+    this_line = extract_stack(limit=2)[-1]

     pa_call_line_synth = (this_line[0], this_line[1]+LINE_DIFF)

 

     def wrapper(*args):

@@ -1052,7 +1052,7 @@ def _trim_arity(func, maxargs=2):
                 else:

                     try:

                         tb = sys.exc_info()[-1]

-                        if not extract_tb(tb)[-1][:2] == pa_call_line_synth:

+                        if not extract_tb(tb, limit=2)[-1][:2] == pa_call_line_synth:

                             raise

                     finally:

                         del tb

diff --git a/src/unitTests.py b/src/unitTests.py
index 87b4beb..1f7964e 100644
--- a/src/unitTests.py
+++ b/src/unitTests.py
@@ -2529,6 +2529,58 @@ class TrimArityExceptionMaskingTest(ParseTestCase):
             exc_msg = str(e)

         assert exc_msg != invalid_message, "failed to catch TypeError thrown in _trim_arity"

 

+class TrimArityExceptionMaskingTest2(ParseTestCase):

+    def runTest(self):

+        

+        

+        # construct deep call tree

+        def A():

+            import traceback

+            

+            traceback.print_stack(limit=2)

+

+            from pyparsing import Word

+            

+            invalid_message = [

+                "<lambda>() takes exactly 1 argument (0 given)",

+                "<lambda>() missing 1 required positional argument: 't'"

+                ][PY_3]

+            try:

+                Word('a').setParseAction(lambda t: t[0]+1).parseString('aaa')

+            except Exception as e:

+                exc_msg = str(e)

+            assert exc_msg != invalid_message, "failed to catch TypeError thrown in _trim_arity"

+

+            

+        def B():

+            A()

+            

+        def C():

+            B()

+            

+        def D():

+            C()

+            

+        def E():

+            D()

+            

+        def F():

+            E()

+            

+        def G():

+            F()

+            

+        def H():

+            G()

+            

+        def J():

+            H()

+            

+        def K():

+            J()

+

+        K()

+

 class OneOrMoreStopTest(ParseTestCase):

     def runTest(self):

         from pyparsing import (Word, OneOrMore, alphas, Keyword, CaselessKeyword,