#?Copyright?（C）?2013-2014?Free?Software?Foundation?Inc.

#?This?program?is?free?software;?you?can?redistribute?it?and/or?modify
#?it?under?the?terms?of?the?GNU?General?Public?License?as?published?by
#?the?Free?Software?Foundation;?either?version?3?of?the?License?or
#?（at?your?option）?any?later?version.
#
#?This?program?is?distributed?in?the?hope?that?it?will?be?useful
#?but?WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of
#?MERCHANTABILITY?or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the
#?GNU?General?Public?License?for?more?details.
#
#?You?should?have?received?a?copy?of?the?GNU?General?Public?License
#?along?with?this?program.??If?not?see?.

import?gdb

#?This?small?code?snippet?deals?with?problem?of?strings?in?Python?2.x
#?and?Python?3.x.??Python?2.x?has?str?and?unicode?classes?which?are
#?sub-classes?of?basestring.??In?Python?3.x?all?strings?are?encoded
#?and?basestring?has?been?removed.
try:
????basestring
except?NameError:
????basestring?=?str

class?frameDecorator（object）:
????“““Basic?implementation?of?a?frame?Decorator“““

????“““?This?base?frame?decorator?decorates?a?frame?or?another?frame
????decorator?and?provides?convenience?methods.??If?this?object?is
????wrapping?a?frame?decorator?defer?to?that?wrapped?object‘s?method
????if?it?has?one.??This?allows?for?frame?decorators?that?have
????sub-classed?frameDecorator?object?but?also?wrap?other?frame
????decorators?on?the?same?frame?to?correctly?execute.

????E.g

????If?the?result?of?frame?filters?running?means?we?have?one?gdb.frame
????wrapped?by?multiple?frame?decorators?all?sub-classed?from
????frameDecorator?the?resulting?hierarchy?will?be:

????Decorator1
??????--?（wraps）?Decorator2
????????--?（wraps）?frameDecorator
??????????--?（wraps）?gdb.frame

????In?this?case?we?have?two?frame?decorators?both?of?which?are
????sub-classed?from?frameDecorator.??If?Decorator1?just?overrides?the
????‘function‘?method?then?all?of?the?other?methods?are?carried?out
????by?the?super-class?frameDecorator.??But?Decorator2?may?have
????overriden?other?methods?so?frameDecorator?will?look?at?the
????‘base‘?parameter?and?defer?to?that?class‘s?methods.??And?so?on
????down?the?chain.“““

????#?‘base‘?can?refer?to?a?gdb.frame?or?another?frame?decorator.??In
????#?the?latter?case?the?child?class?will?have?called?the?super
????#?method?and?_base?will?be?an?object?conforming?to?the?frame?Filter
????#?class.
????def?__init__（self?base）:
????????self._base?=?base

????@staticmethod
????def?_is_limited_frame（frame）:
????????“““Internal?utility?to?determine?if?the?frame?is?special?or
????????limited.“““
????????sal?=?frame.find_sal（）

????????if?（not?sal.symtab?or?not?sal.symtab.filename
????????????or?frame.type（）?==?gdb.DUMMY_frame
????????????or?frame.type（）?==?gdb.SIGTRAMP_frame）:

????????????return?True

????????return?False

????def?elided（self）:
????????“““Return?any?elided?frames?that?this?class?might?be
????????wrapping?or?None.“““
????????if?hasattr（self._