Add pretty printer for literal null, undefined, MinKey, and MaxKey.

Author: visemet

gdbmongo/bsonmisc_printer.py

@@ -26,6 +26,7 @@
 import gdb
 
 from gdbmongo.objectid_printer import MongoOID
+from gdbmongo.printer_protocol import SupportsToString
 from gdbmongo.string_data_printer import MongoStringData
 
 
@@ -212,3 +213,62 @@ def to_value(self) -> gdb.Value:
 
 setattr(MongoBSONSymbol, "_fields_",
         [(field.name, field.type) for field in dataclasses.fields(MongoBSONSymbol)])
+
+
+# pylint: disable-next=too-few-public-methods
+class UndefinedLabelerPrinter(SupportsToString):
+    # pylint: disable=missing-function-docstring
+    """Pretty-printer for literal undefined value."""
+
+    def __init__(self, val: gdb.Value, /) -> None:
+        self.val = val
+
+    def to_string(self) -> str:
+        return "undefined"
+
+
+# pylint: disable-next=too-few-public-methods
+class NullLabelerPrinter(SupportsToString):
+    # pylint: disable=missing-function-docstring
+    """Pretty-printer for literal null value."""
+
+    def __init__(self, val: gdb.Value, /) -> None:
+        self.val = val
+
+    def to_string(self) -> str:
+        return "null"
+
+
+# pylint: disable-next=too-few-public-methods
+class MinKeyLabelerPrinter(SupportsToString):
+    # pylint: disable=missing-function-docstring
+    """Pretty-printer for literal MinKey value."""
+
+    def __init__(self, val: gdb.Value, /) -> None:
+        self.val = val
+
+    def to_string(self) -> str:
+        return "MinKey()"
+
+
+# pylint: disable-next=too-few-public-methods
+class MaxKeyLabelerPrinter(SupportsToString):
+    # pylint: disable=missing-function-docstring
+    """Pretty-printer for literal MaxKey value."""
+
+    def __init__(self, val: gdb.Value, /) -> None:
+        self.val = val
+
+    def to_string(self) -> str:
+        return "MaxKey()"
+
+
+def add_printers(pretty_printer: gdb.printing.RegexpCollectionPrettyPrinter, /) -> None:
+    """Add the BSON-related printers to the pretty printer collection given."""
+    pretty_printer.add_printer("mongo::MaxKeyLabeler", "^mongo::MaxKeyLabeler$",
+                               MaxKeyLabelerPrinter)
+    pretty_printer.add_printer("mongo::MinKeyLabeler", "^mongo::MinKeyLabeler$",
+                               MinKeyLabelerPrinter)
+    pretty_printer.add_printer("mongo::NullLabeler", "^mongo::NullLabeler$", NullLabelerPrinter)
+    pretty_printer.add_printer("mongo::UndefinedLabeler", "^mongo::UndefinedLabeler$",
+                               UndefinedLabelerPrinter)

gdbmongo/interaction.py

@@ -22,8 +22,9 @@
 import gdb
 import gdb.printing
 
-from gdbmongo import (abseil_printers, date_printer, decorable_printer, lock_manager_printer,
-                      objectid_printer, string_data_printer, timestamp_printer)
+from gdbmongo import (abseil_printers, bsonmisc_printer, date_printer, decorable_printer,
+                      lock_manager_printer, objectid_printer, string_data_printer,
+                      timestamp_printer)
 from gdbmongo.detect_toolchain import ToolchainVersionDetector
 from gdbmongo.printer_protocol import SupportsChildren, SupportsToString
 from gdbmongo.stdlib_printers_loader import resolve_import
@@ -83,6 +84,7 @@ def register_printers(*, essentials: bool = True, stdlib: bool = False, abseil:
 
     if mongo_extras:
         pretty_printer_mongo_extras = RegexpCollectionPrettyPrinter("gdbmongo-mongo-extras")
+        bsonmisc_printer.add_printers(pretty_printer_mongo_extras)
         date_printer.add_printers(pretty_printer_mongo_extras)
         decorable_printer.add_printers(pretty_printer_mongo_extras)
         objectid_printer.add_printers(pretty_printer_mongo_extras)