[lldb] Accept negative indexes in __getitem__

[kastiglione]

Summary

To the Python bindings, add support for Python-like indexing with negative indexes.

While was using script, I tried to access a thread's bottom frame with thread.frame[-1], but that failed. This change updates the __getitem__ implementations to support negative indexes as one would expect in Python.

[mib]

This is nice although I wish there was a builtin way to do it. LGTM with a test :)

[kastiglione]

I wondered what to do about tests. Should I pick one of these to test? Just
doesn't seem worth tests for each…

[mib]

In D143282#4103165, @kastiglione wrote:

I wondered what to do about tests. Should I pick one of these to test? Just
doesn't seem worth tests for each…

Yeah, that sounds good to me :)

[bulbazord]

A simple test would be what you did in your commit summary, trying to get thread.frame[-1] and verifying that it's the correct frame. LGTM with a test.

[kastiglione]

Add a couple tests

lldb/bindings/interface/SBBreakpoint.i

%pythoncode %{
                 self.sbbreakpoint = sbbreakpoint
 
             def __len__(self):
                 if self.sbbreakpoint:
                     return int(self.sbbreakpoint.GetNumLocations())
                 return 0
 
             def __getitem__(self, key):
-                if type(key) is int and key < len(self):
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
                         return self.sbbreakpoint.GetLocationAtIndex(key)
                 return None
 
         def get_locations_access_object(self):
             '''An accessor function that returns a locations_access() object which allows lazy location access from a lldb.SBBreakpoint object.'''
             return self.locations_access (self)
 
         def get_breakpoint_location_list(self):
             '''An accessor function that returns a list() that contains all locations in a lldb.SBBreakpoint object.'''

lldb/bindings/interface/SBInstructionList.i

%pythoncode %{
         def __len__(self):
             '''Access len of the instruction list.'''
             return int(self.GetSize())
 
         def __getitem__(self, key):
             '''Access instructions by integer index for array access or by lldb.SBAddress to find an instruction that matches a section offset address object.'''
             if type(key) is int:
                 # Find an instruction by index
-                if key < len(self):
+                count = len(self)
+                if -count <= key < count:
+                    key %= count
                     return self.GetInstructionAtIndex(key)
             elif type(key) is SBAddress:
                 # Find an instruction using a lldb.SBAddress object
                 lookup_file_addr = key.file_addr
                 closest_inst = None
                 for idx in range(self.GetSize()):
                     inst = self.GetInstructionAtIndex(idx)
                     inst_file_addr = inst.addr.file_addr

lldb/bindings/interface/SBModule.i

%pythoncode %{
             def __len__(self):
                 if self.sbmodule:
                     return int(self.sbmodule.GetNumSymbols())
                 return 0
 
             def __getitem__(self, key):
                 count = len(self)
                 if type(key) is int:
-                    if key < count:
+                    if -count <= key < count:
+                        key %= count
                         return self.sbmodule.GetSymbolAtIndex(key)
                 elif type(key) is str:
                     matches = []
                     sc_list = self.sbmodule.FindSymbols(key)
                     for sc in sc_list:
                         symbol = sc.symbol
                         if symbol:
                             matches.append(symbol)
%pythoncode %{
             def __len__(self):
                 if self.sbmodule:
                     return int(self.sbmodule.GetNumSections())
                 return 0
 
             def __getitem__(self, key):
                 count = len(self)
                 if type(key) is int:
-                    if key < count:
+                    if -count <= key < count:
+                        key %= count
                         return self.sbmodule.GetSectionAtIndex(key)
                 elif type(key) is str:
                     for idx in range(count):
                         section = self.sbmodule.GetSectionAtIndex(idx)
                         if section.name == key:
                             return section
                 elif isinstance(key, self.re_compile_type):
                     matches = []
%pythoncode %{
             def __len__(self):
                 if self.sbmodule:
                     return int(self.sbmodule.GetNumCompileUnits())
                 return 0
 
             def __getitem__(self, key):
                 count = len(self)
                 if type(key) is int:
-                    if key < count:
+                    if -count <= key < count:
+                        key %= count
                         return self.sbmodule.GetCompileUnitAtIndex(key)
                 elif type(key) is str:
                     is_full_path = key[0] == '/'
                     for idx in range(count):
                         comp_unit = self.sbmodule.GetCompileUnitAtIndex(idx)
                         if is_full_path:
                             if comp_unit.file.fullpath == key:
                                 return comp_unit

lldb/bindings/interface/SBProcess.i

%pythoncode %{
                 self.sbprocess = sbprocess
 
             def __len__(self):
                 if self.sbprocess:
                     return int(self.sbprocess.GetNumThreads())
                 return 0
 
             def __getitem__(self, key):
-                if type(key) is int and key < len(self):
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
                         return self.sbprocess.GetThreadAtIndex(key)
                 return None
 
         def get_threads_access_object(self):
             '''An accessor function that returns a modules_access() object which allows lazy thread access from a lldb.SBProcess object.'''
             return self.threads_access (self)
 
         def get_process_thread_list(self):
             '''An accessor function that returns a list() that contains all threads in a lldb.SBProcess object.'''

lldb/bindings/interface/SBSymbolContextList.i

%pythoncode %{
             object.'''
             return lldb_iter(self, 'GetSize', 'GetContextAtIndex')
 
         def __len__(self):
             return int(self.GetSize())
 
         def __getitem__(self, key):
             count = len(self)
-            if type(key) is int:
-                if key < count:
+            if isinstance(key, int):
+                if -count <= key < count:
+                    key %= count
                     return self.GetContextAtIndex(key)
                 else:
                     raise IndexError
             raise TypeError
 
         def get_module_array(self):
             a = []
             for i in range(len(self)):

lldb/bindings/interface/SBTarget.i

%pythoncode %{
             def __len__(self):
                 if self.sbtarget:
                     return int(self.sbtarget.GetNumModules())
                 return 0
 
             def __getitem__(self, key):
                 num_modules = self.sbtarget.GetNumModules()
                 if type(key) is int:
-                    if key < num_modules:
+                    if -num_modules <= key < num_modules:
+                        key %= num_modules
                         return self.sbtarget.GetModuleAtIndex(key)
                 elif type(key) is str:
                     if key.find('/') == -1:
                         for idx in range(num_modules):
                             module = self.sbtarget.GetModuleAtIndex(idx)
                             if module.file.basename == key:
                                 return module
                     else:

lldb/bindings/interface/SBThread.i

%pythoncode %{
                 self.sbthread = sbthread
 
             def __len__(self):
                 if self.sbthread:
                     return int(self.sbthread.GetNumFrames())
                 return 0
 
             def __getitem__(self, key):
-                if type(key) is int and key < self.sbthread.GetNumFrames():
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
                         return self.sbthread.GetFrameAtIndex(key)
                 return None
 
         def get_frames_access_object(self):
             '''An accessor function that returns a frames_access() object which allows lazy frame access from a lldb.SBThread object.'''
             return self.frames_access (self)
 
         def get_thread_frames(self):
             '''An accessor function that returns a list() that contains all frames in a lldb.SBThread object.'''

lldb/bindings/interface/SBTypeCategory.i

#ifdef SWIGPYTHON
                 def __len__(self):
                     if self.sbcategory and self.get_count_function:
                         return int(self.get_count_function(self.sbcategory))
                     return 0
 
                 def __getitem__(self, key):
                     num_items = len(self)
                     if type(key) is int:
-                        if key < num_items:
+                        if -num_items <= key < num_items:
+                            key %= num_items
                             return self.get_at_index_function(self.sbcategory,key)
                     elif type(key) is str:
                         return self.get_by_name_function(self.sbcategory,SBTypeNameSpecifier(key))
                     elif isinstance(key,self.regex_type):
                         return self.get_by_name_function(self.sbcategory,SBTypeNameSpecifier(key.pattern,True))
                     else:
                         print("error: unsupported item type: %s" % type(key))
                     return None

lldb/bindings/interface/SBTypeEnumMember.i

%pythoncode %{
 
         def __len__(self):
             '''Return the number of members in a lldb.SBTypeEnumMemberList object.'''
             return self.GetSize()
 
         def __getitem__(self, key):
           num_elements = self.GetSize()
           if type(key) is int:
-              if key < num_elements:
+              if -num_elements <= key < num_elements:
+                  key %= num_elements
                   return self.GetTypeEnumMemberAtIndex(key)
           elif type(key) is str:
               for idx in range(num_elements):
                   item = self.GetTypeEnumMemberAtIndex(idx)
                   if item.name == key:
                       return item
           return None
     %}
 #endif
 
 private:
     std::unique_ptr<lldb_private::TypeEnumMemberListImpl> m_opaque_ap;
 };
 
 } // namespace lldb

lldb/bindings/interface/SBValue.i

%pythoncode %{
                 self.sbvalue = sbvalue
 
             def __len__(self):
                 if self.sbvalue:
                     return int(self.sbvalue.GetNumChildren())
                 return 0
 
             def __getitem__(self, key):
-                if type(key) is int and key < len(self):
+                if isinstance(key, int):
+                    count = len(self)
+                    if -count <= key < count:
+                        key %= count
                         return self.sbvalue.GetChildAtIndex(key)
                 return None
 
         def get_child_access_object(self):
             '''An accessor function that returns a children_access() object which allows lazy member variable access from a lldb.SBValue object.'''
             return self.children_access (self)
 
         def get_value_child_list(self):
             '''An accessor function that returns a list() that contains all children in a lldb.SBValue object.'''

lldb/bindings/interface/SBValueList.i

%pythoncode %{
             return int(self.GetSize())
 
         def __getitem__(self, key):
             count = len(self)
             #------------------------------------------------------------
             # Access with "int" to get Nth item in the list
             #------------------------------------------------------------
             if type(key) is int:
-                if key < count:
+                if -count <= key < count:
+                    key %= count
                     return self.GetValueAtIndex(key)
             #------------------------------------------------------------
             # Access with "str" to get values by name
             #------------------------------------------------------------
             elif type(key) is str:
                 matches = []
                 for idx in range(count):
                     value = self.GetValueAtIndex(idx)