From 4da644edf60e238d74334f121d5d07870496e368 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gerd=20M=C3=B6llmann?= <gerd@gnu.org>
Date: Mon, 9 Oct 2023 15:20:37 +0200
Subject: [PATCH] ; LLDB synthetic child provider

---
 etc/emacs_lldb.py | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/etc/emacs_lldb.py b/etc/emacs_lldb.py
index f92a7e03a41..24b127a1fb9 100644
--- a/etc/emacs_lldb.py
+++ b/etc/emacs_lldb.py
@@ -88,7 +88,7 @@ class Lisp_Object:
         self.init_values()
 
     def init_unsigned(self):
-        if self.lisp_obj.GetNumChildren() != 0:
+        if self.lisp_obj.GetType().GetTypeClass() == lldb.eTypeClassStruct:
             # Lisp_Object is actually a struct.
             lisp_word = self.lisp_obj.GetValueForExpressionPath(".i")
             self.unsigned = lisp_word.GetValueAsUnsigned()
@@ -213,6 +213,41 @@ def xdebug_print(debugger, command, result, internal_dict):
 def type_summary_Lisp_Object(obj, internal_dict):
     return Lisp_Object(obj).summary()
 
+# Don't know at the moment how to use this outside of the LLDB gui
+# command.  And it's still incomplete.
+class Lisp_Object_Provider:
+    def __init__(self, valobj, internal_dict):
+        self.valobj = valobj
+        self.lisp_obj = Lisp_Object(valobj)
+        self.child = None
+
+    def update(self):
+        if self.lisp_obj.lisp_type == "Lisp_Symbol":
+            self.child = self.lisp_obj.get_symbol_name().Clone("name")
+            self.child.SetSyntheticChildGenerated(True)
+        elif self.lisp_obj.lisp_type == "Lisp_String":
+            self.child = self.lisp_obj.get_string_data().Clone("data")
+            self.child.SetSyntheticChildGenerated(True)
+        else:
+            self.child = self.lisp_obj.value.Clone("untagged")
+            self.child.SetSyntheticChildGenerated(True)
+
+    def has_children(self):
+        return True
+
+    def num_children(self):
+        return 1
+
+    def get_child_index(self, name):
+        return 0
+
+    # This works insofar as struct frame * works, but it doesn't work
+    # Lisp_Symbol, for example.
+    def get_child_at_index(self, index):
+        if index != 0:
+            return None
+        return self.child
+
 
 ########################################################################
 #                           Initialization
@@ -246,6 +281,17 @@ def define_type_summary(debugger, regex, function):
                            f"--python-function {python_function} "
                            + regex)
 
+# Define Python class CLS as a children provider for the types
+# matching REFEXP.  Providers are defined in the category Emacs, and
+# can be seen with 'type synthetic list -w Emacs', and deleted in a
+# similar way.
+def define_type_synthetic(debugger, regex, cls):
+    python_class = __name__ + "." + cls.__name__
+    debugger.HandleCommand(f"type synthetic add "
+                           f"--category Emacs "
+                           f"--python-class {python_class} "
+                           + regex)
+
 # Enable a given category of type summary providers.
 def enable_type_category(debugger, category):
     debugger.HandleCommand(f"type category enable {category}")
@@ -255,6 +301,7 @@ def __lldb_init_module(debugger, internal_dict):
     define_command(debugger, xbacktrace)
     define_command(debugger, xdebug_print)
     define_type_summary(debugger, "Lisp_Object", type_summary_Lisp_Object)
+    define_type_synthetic(debugger, "Lisp_Object", Lisp_Object_Provider)
     enable_type_category(debugger, "Emacs")
     print('Emacs debugging support has been installed.')
 
-- 
2.39.2