Replace usage of StdVectorPrinter.Iterator's item and finish attributes.

The attributes were renamed as part of
gcc-mirror/gcc@64f1210, which leaves
VectorSizeWorker as the stable API definition in all libstdc++ pretty
printer versions we support.

Author: visemet

gdbmongo/decorable_printer.py

@@ -35,6 +35,7 @@
 import gdb
 
 from gdbmongo import stdlib_printers, stdlib_xmethods
+from gdbmongo.libstdcxxutil import vector_size
 from gdbmongo.printer_protocol import PrettyPrinterProtocol
 
 
@@ -153,8 +154,7 @@ def __init__(self, val: gdb.Value, /) -> None:
             fr"^void {registry_type.name}::constructAt<\s*(.*)\s*>\(void\*\)$")
 
     def __len__(self) -> int:
-        iterator = stdlib_printers.StdVectorPrinter("std::vector", self.decorations_info).children()
-        length = int(iterator.finish - iterator.item)
+        length = int(vector_size(self.decorations_info))
         return length
 
     def _iterate_raw_entries(self) -> typing.Iterator[typing.Tuple[gdb.Type, gdb.Value]]:
@@ -287,8 +287,7 @@ def __init__(self, val: gdb.Value, /) -> None:
             self._offset_field_name = "_offset"
 
     def __len__(self) -> int:
-        iterator = stdlib_printers.StdVectorPrinter("std::vector", self.registry_entries).children()
-        length = int(iterator.finish - iterator.item)
+        length = int(vector_size(self.registry_entries))
         return length
 
     def _iterate_raw_entries(self) -> typing.Iterator[typing.Tuple[gdb.Type, gdb.Value]]:

gdbmongo/libstdcxxutil.py

@@ -24,3 +24,9 @@ def shared_ptr_get(obj: gdb.Value, /) -> gdb.Value:
     """Return the stored T* pointer underlying a std::shared_ptr<T>."""
     xmethod_worker = stdlib_xmethods.SharedPtrMethodsMatcher().match(obj.type, "get")
     return xmethod_worker(obj)
+
+
+def vector_size(obj: gdb.Value, /) -> gdb.Value:
+    """Return the number of elements in a std::vector<T>."""
+    xmethod_worker = stdlib_xmethods.VectorMethodsMatcher().match(obj.type, "size")
+    return xmethod_worker(obj)

gdbmongo/stdlib_printers.pyi

@@ -81,14 +81,7 @@ class StdVectorPrinter(__PrettyPrinterProtocol):
         ...
 
     class Iterator(typing.Iterator[typing.Tuple[str, gdb.Value]], metaclass=abc.ABCMeta):
-
-        @property
-        def item(self) -> gdb.Value:
-            ...
-
-        @property
-        def finish(self) -> gdb.Value:
-            ...
+        ...
 
     def children(self) -> Iterator:
         ...