[Predator] Move ``FilterStackBuffer`` from stack parser to ``AddFilteredStack`` of stacktrace buffe…

appengine/findit/crash/chromecrash_parser.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import math
 import re
 
 from crash import callstack_filters
 from crash.stacktrace import CallStackBuffer
 from crash.stacktrace import StacktraceBuffer
 from crash.stacktrace import StackFrame
 from crash.stacktrace import Stacktrace
 from crash.stacktrace_parser import StacktraceParser
 from crash.type_enums import CallStackFormatType
 from crash.type_enums import LanguageType
 
 FRACAS_CALLSTACK_START_PATTERN = re.compile(r'CRASHED \[(.*) @ 0x(.*)\]')
 JAVA_CALLSTACK_START_PATTERN = re.compile(r'\(JAVA\) CRASHED \[(.*) @ 0x(.*)\]')
 DEFAULT_TOP_N_FRAMES = 7
 
 
 class ChromeCrashParser(StacktraceParser):
 
   def Parse(self, stacktrace_string, deps, signature=None, top_n_frames=None):
     """Parse fracas stacktrace string into Stacktrace instance."""
-    stacktrace_buffer = StacktraceBuffer(signature=signature)
     # Filters to filter callstack buffers.
     filters = [callstack_filters.FilterInlineFunction(),
                callstack_filters.KeepTopNFrames(top_n_frames or
                                                 DEFAULT_TOP_N_FRAMES)]
+    stacktrace_buffer = StacktraceBuffer(signature=signature, filters=filters)
 
     # Initial background callstack which is not to be added into Stacktrace.
     stack_buffer = CallStackBuffer()
     for line in stacktrace_string.splitlines():
       is_new_callstack, priority, format_type, language_type = (
           self._IsStartOfNewCallStack(line))
 
       if is_new_callstack:
-        # TODO(katesonia): Refactor this logic to ``AddFilteredStack`` method
-        # of StacktraceBuffer.
-        stack_buffer = StacktraceParser.FilterStackBuffer(stack_buffer, filters)
-        if stack_buffer:
-          stacktrace_buffer.stacks.append(stack_buffer)
-
+        stacktrace_buffer.AddFilteredStack(stack_buffer)
         stack_buffer = CallStackBuffer(priority=priority,
                                        format_type=format_type,
                                        language_type=language_type)
       else:
         frame = StackFrame.Parse(stack_buffer.language_type,
                                  stack_buffer.format_type, line, deps,
                                  len(stack_buffer.frames))
         if frame is not None:
           stack_buffer.frames.append(frame)
 
-    stack_buffer = StacktraceParser.FilterStackBuffer(stack_buffer, filters)
-    if stack_buffer:
-      stacktrace_buffer.stacks.append(stack_buffer)
+    # Add the last stack to stacktrace.
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
 
     return stacktrace_buffer.ToStacktrace()
 
   def _IsStartOfNewCallStack(self, line):
     """Determine whether a line is a start of a callstack or not.
 
     Returns a tuple - (is_new_callstack, stack_priority, format_type,
     language type).
     """
     if FRACAS_CALLSTACK_START_PATTERN.match(line):
       #Fracas only provide magic signature stack (crash stack).
       return True, 0, CallStackFormatType.DEFAULT, LanguageType.CPP
 
     if JAVA_CALLSTACK_START_PATTERN.match(line):
       return True, 0, CallStackFormatType.DEFAULT, LanguageType.JAVA
 
     return False, None, None, None