[lldb] Add scripted thread plan python base class to lldb & website (#97481)

Following a feedback request in #97262, I took out the scripted thread
plan python base class from it and make a separate PR for it.

This patch adds the scripted thread plan base python class to the lldb
python module as well as the lldb documentation website.

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>

lldb/bindings/python/CMakeLists.txt

@@ -108,7 +108,9 @@ function(finish_swig_python swig_target lldb_python_bindings_dir lldb_python_tar
     "${LLDB_SOURCE_DIR}/examples/python/templates/parsed_cmd.py"
     "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_process.py"
     "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_platform.py"
-    "${LLDB_SOURCE_DIR}/examples/python/templates/operating_system.py")
+    "${LLDB_SOURCE_DIR}/examples/python/templates/operating_system.py"
+    "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_thread_plan.py"
+    )
 
   if(APPLE)
     create_python_package(

lldb/docs/CMakeLists.txt

@@ -31,6 +31,7 @@ if (LLDB_ENABLE_PYTHON AND SPHINX_FOUND)
       COMMAND "${CMAKE_COMMAND}" -E copy "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_process.py" "${CMAKE_CURRENT_BINARY_DIR}/lldb/plugins/"
       COMMAND "${CMAKE_COMMAND}" -E copy "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_platform.py" "${CMAKE_CURRENT_BINARY_DIR}/lldb/plugins/"
       COMMAND "${CMAKE_COMMAND}" -E copy "${LLDB_SOURCE_DIR}/examples/python/templates/operating_system.py" "${CMAKE_CURRENT_BINARY_DIR}/lldb/plugins/"
+      COMMAND "${CMAKE_COMMAND}" -E copy "${LLDB_SOURCE_DIR}/examples/python/templates/scripted_thread_plan.py" "${CMAKE_CURRENT_BINARY_DIR}/lldb/plugins/"
       COMMENT "Copying lldb.py to pretend its a Python package.")
 
     add_dependencies(lldb-python-doc-package swig_wrapper_python lldb-python)

lldb/docs/python_extensions.rst

@@ -0,0 +1,39 @@
+Python Extensions
+=================
+
+LLDB provides scriptable extensions to augment the debugger's capabilities.
+This gives users the ability to tailor their debugging experience to their own needs.
+
+This page describes some of these scripting extensions:
+
+Operating System Thread Plugins
+-------------------------------
+
+.. automodapi:: lldb.plugins.operating_system
+    :no-heading:
+    :skip: ScriptedThread
+    :no-inheritance-diagram:
+
+Scripted Process Plugins
+-------------------------------
+
+.. automodapi:: lldb.plugins.scripted_process
+    :no-heading:
+    :skip: ABCMeta
+    :no-inheritance-diagram:
+
+Scripted Platform Plugins
+-------------------------------
+
+.. automodapi:: lldb.plugins.scripted_platform
+    :no-heading:
+    :skip: ABCMeta
+    :no-inheritance-diagram:
+
+Scripted Thread Plan Plugins
+-------------------------------
+
+.. automodapi:: lldb.plugins.scripted_thread_plan
+    :no-heading:
+    :no-inheritance-diagram:
+

lldb/examples/python/templates/scripted_thread_plan.py

@@ -0,0 +1,70 @@
+from abc import abstractmethod
+
+import lldb
+
+
+class ScriptedThreadPlan:
+    """
+    Class that provides data for an instance of a LLDB 'ScriptedThreadPlan' plug-in class used to construct custom stepping logic.
+
+    """
+
+    def __init__(self, thread_plan: lldb.SBThreadPlan):
+        """Initialization needs a valid lldb.SBThreadPlan object. This plug-in will get created after a live process is valid and has stopped.
+
+        Args:
+            thread_plan (lldb.SBThreadPlan): The underlying `ThreadPlan` that is pushed onto the plan stack.
+        """
+        self.thread_plan = thread_plan
+
+    def explains_stop(self, event: lldb.SBEvent) -> bool:
+        """Each plan is asked from youngest to oldest if it "explains" the stop. The first plan to claim the stop wins.
+
+        Args:
+            event (lldb.SBEvent): The process stop event.
+
+        Returns:
+            bool: `True` if this stop could be claimed by this thread plan, `False` otherwise.
+            Defaults to `True`.
+        """
+        return True
+
+    def is_stale(self) -> bool:
+        """If your plan is no longer relevant (for instance, you were stepping in a particular stack frame, but some other operation pushed that frame off the stack) return True and your plan will get popped.
+
+        Returns:
+            bool: `True` if this thread plan is stale, `False` otherwise.
+            Defaults to `False`.
+        """
+        return False
+
+    def should_stop(self, event: lldb.SBEvent) -> bool:
+        """Whether this thread plan should stop and return control to the user.
+        If your plan is done at this point, call SetPlanComplete on your thread plan instance. Also, do any work you need here to set up the next stage of stepping.
+
+        Args:
+            event (lldb.SBEvent): The process stop event.
+
+        Returns:
+            bool: `True` if this plan wants to stop and return control to the user at this point, `False` otherwise.
+            Defaults to `False`.
+        """
+        self.thread_plan.SetPlanComplete(True)
+        return True
+
+    def should_step(self) -> bool:
+        """Whether this thread plan should instruction step one instruction, or continue till the next breakpoint is hit.
+
+        Returns:
+            bool: `True` if this plan will instruction step one instruction, `False` otherwise.
+            Defaults to `True`.
+        """
+        return True
+
+    def stop_description(self, stream: lldb.SBStream) -> None:
+        """Customize the thread plan stop reason when the thread plan is complete.
+
+        Args:
+            stream (lldb.SBStream): The stream containing the stop description.
+        """
+        pass