basic-fabric.py

from time import sleep
import json

# Simplified version of get_node_from_instance
def get_node_from_instance(inst):
 # For simplicity, we assume inst is already the node.
 return inst

# Guarded Callback Handling
def invoke_guarded_callback_impl(name, func, context, *args):
 try:
 func(context, *args)
 except Exception as error:
 reporter.on_error(error)

class Reporter:
 def __init__(self):
 self.has_error = False
 self.caught_error = None

 def on_error(self, error):
 self.has_error = True
 self.caught_error = error

reporter = Reporter()

# Synthetic Event System
class SyntheticEvent:
 def __init__(self, dispatch_config, target_inst, native_event, native_event_target):
 self.dispatch_config = dispatch_config
 self._target_inst = target_inst
 self.native_event = native_event
 self._dispatch_instances = self._dispatch_listeners = None
 dispatch_config = self.__class__.Interface
 for prop_name in dispatch_config:
 if prop_name in dispatch_config:
 self[prop_name] = dispatch_config[prop_name](native_event) if dispatch_config[prop_name] else native_event.get(prop_name, None)
 self.target = native_event_target

 def prevent_default(self):
 self.is_default_prevented = True

 def stop_propagation(self):
 self.is_propagation_stopped = True


# Responder Event Handling
class ResponderSyntheticEvent(SyntheticEvent):
 def __init__(self, dispatch_config, target_inst, native_event, native_event_target):
 super().__init__(dispatch_config, target_inst, native_event, native_event_target)
 self.touch_history = None

class ResponderEventPlugin:
 @staticmethod
 def extract_events(top_level_type, target_inst, native_event, native_event_target):
 # Implement touch event extraction logic here, similar to JavaScript version
 pass

# Node Creation and Updates
class Node:
 def __init__(self, node_type, props=None, context=None):
 self.node_type = node_type
 self.props = props or {}
 self.context = context
 self.children = []

 def add_child(self, child):
 self.children.append(child)

 def update_props(self, new_props):
 self.props.update(new_props)

 def to_dict(self):
 """Recursively converts the node and its children to a dictionary."""
 return {
 "node_type": self.node_type,
 "props": self.props,
 "children": [child.to_dict() for child in self.children]
 }

 def to_json(self):
 """Converts the node tree to a JSON string."""
 return json.dumps(self.to_dict(), indent=4)
 

# Creating and cloning nodes
def create_node(context, node_type, root_container, props, internal_instance_handle):
 return Node(node_type, props, context)

def clone_node_with_new_props(node, new_props):
 node.update_props(new_props)
 return node

# Guarded callback wrapper to catch and handle errors
def invoke_guarded_callback_and_catch_first_error(listener, event):
 try:
 listener(event) # Execute the listener with the event
 except Exception as e:
 print(f"Error occurred while executing callback: {e}")
 # Additional error handling logic can go here if needed


# Event Dispatching
def execute_dispatch(event, listener, inst):
 event.current_target = get_node_from_instance(inst)
 invoke_guarded_callback_and_catch_first_error(listener, event)
 event.current_target = None

def execute_direct_dispatch(event):
 dispatch_listener = event._dispatch_listeners
 event.current_target = dispatch_listener and get_node_from_instance(event._dispatch_instances) or None
 if dispatch_listener:
 dispatch_listener(event)
 event.current_target = None
 event._dispatch_listeners = None
 event._dispatch_instances = None
 return dispatch_listener


def schedule_callback(callback, priority=1):
 sleep(priority) # Simulate delay based on priority
 callback()

def cancel_callback(callback):
 # Logic to cancel the scheduled callback (if needed)
 pass

def should_yield():
 # Placeholder to control when to yield to other tasks
 return False

# Basic Reconciliation Logic
def diff_trees(old_node, new_node):
 changes = []

 # Type change
 if old_node.node_type != new_node.node_type:
 changes.append(("REPLACE", new_node))
 return changes

 # Prop change
 for key in new_node.props:
 if new_node.props.get(key) != old_node.props.get(key):
 changes.append(("UPDATE_PROP", key, new_node.props[key]))

 # Child changes
 old_children = old_node.children
 new_children = new_node.children
 for i, child in enumerate(new_children):
 if i < len(old_children):
 changes.extend(diff_trees(old_children[i], child))
 else:
 changes.append(("ADD_CHILD", child))

 return changes

# Node Update Handling
def apply_changes(node, changes):
 for change in changes:
 if change[0] == "REPLACE":
 node = change[1] # Replace the node with the new one
 elif change[0] == "UPDATE_PROP":
 node.props[change[1]] = change[2] # Update the property
 elif change[0] == "ADD_CHILD":
 node.add_child(change[1]) # Add a new child
 return node

# Simplified Scheduler and Task Management
class Task:
 def __init__(self, callback, priority=1):
 self.callback = callback
 self.priority = priority

class Scheduler:
 def __init__(self):
 self.queue = []

 def schedule(self, task):
 self.queue.append(task)
 self.queue.sort(key=lambda x: x.priority, reverse=True) # Sort by priority

 def run(self):
 while self.queue:
 task = self.queue.pop(0)
 task.callback()

# Example usage of Scheduler
scheduler = Scheduler()
scheduler.schedule(Task(lambda: print("Task 1"), priority=2))
scheduler.schedule(Task(lambda: print("Task 2"), priority=1))
scheduler.run()

# UI Rendering Logic
class Renderer:
 def __init__(self):
 self.root_node = None

 def set_root(self, root_node):
 self.root_node = root_node

 def render(self):
 if self.root_node:
 self._render_node(self.root_node)

 def _render_node(self, node):
 print(f"Rendering {node.node_type} with props: {node.props}")
 for child in node.children:
 self._render_node(child)

# Example of setting up and rendering a simple UI
root = Node("View", {"style": "background-color: blue"})
child = Node("Text", {"value": "Hello, World!"})
root.add_child(child)

renderer = Renderer()
renderer.set_root(root)
renderer.render()

# Simplified Event Propagation
class Event:
 def __init__(self, type, target):
 self.type = type
 self.target = target
 self.current_target = target
 self.is_propagation_stopped = False
 self.is_default_prevented = False

 def stop_propagation(self):
 self.is_propagation_stopped = True

 def prevent_default(self):
 self.is_default_prevented = True

class EventDispatcher:
 def __init__(self):
 self.listeners = {}

 def add_event_listener(self, target, event_type, listener):
 if target not in self.listeners:
 self.listeners[target] = {}
 if event_type not in self.listeners[target]:
 self.listeners[target][event_type] = []
 self.listeners[target][event_type].append(listener)

 def dispatch_event(self, event):
 if event.target in self.listeners and event.type in self.listeners[event.target]:
 for listener in self.listeners[event.target][event.type]:
 listener(event)
 if event.is_propagation_stopped:
 break

# React-like Component System
class Component:
 def __init__(self, props=None):
 self.props = props or {}
 self.state = {}

 def set_state(self, new_state):
 self.state.update(new_state)
 self.render()

 def render(self):
 raise NotImplementedError("Subclasses must implement render()")

class View(Component):
 def __init__(self, props=None):
 super().__init__(props)

 def render(self):
 print(f"Rendering View with props: {self.props} and state: {self.state}")

class Text(Component):
 def __init__(self, props=None):
 super().__init__(props)

 def render(self):
 print(f"Rendering Text with props: {self.props} and state: {self.state}")

# Example of usage
view = View({"style": "background-color: red"})
text = Text({"value": "Hello, ReactPy!"})

view.set_state({"background_color": "blue"})
view.render()
text.render()

# Node Reconciliation and Diffing
def reconcile(old_node, new_node):
 changes = []

 # Check if node types are different
 if old_node.node_type != new_node.node_type:
 changes.append(("REPLACE", new_node))
 return changes

 # Check if node properties have changed
 for key, value in new_node.props.items():
 if old_node.props.get(key) != value:
 changes.append(("UPDATE_PROP", key, value))

 # Handle child nodes (diffing them)
 old_children = old_node.children
 new_children = new_node.children

 for i, new_child in enumerate(new_children):
 if i < len(old_children):
 changes.extend(reconcile(old_children[i], new_child))
 else:
 changes.append(("ADD_CHILD", new_child))

 # Remove any extra children
 for i in range(len(new_children), len(old_children)):
 changes.append(("REMOVE_CHILD", old_children[i]))

 return changes

# Applying Changes to Nodes
def apply_reconciliation_changes(node, changes):
 for change in changes:
 if change[0] == "REPLACE":
 node = change[1] # Replace the node with a new one
 elif change[0] == "UPDATE_PROP":
 node.props[change[1]] = change[2] # Update the property
 elif change[0] == "ADD_CHILD":
 node.add_child(change[1]) # Add a new child
 elif change[0] == "REMOVE_CHILD":
 node.children.remove(change[1]) # Remove the child
 return node

# Component Lifecycle
class Component:
 def __init__(self, props=None):
 self.props = props or {}
 self.state = {}
 self._is_mounted = False

 def set_state(self, new_state):
 self.state.update(new_state)
 self.render()

 def render(self):
 raise NotImplementedError("Subclasses must implement render()")

 def component_did_mount(self):
 print(f"{self.__class__.__name__} mounted.")

 def component_will_unmount(self):
 print(f"{self.__class__.__name__} will unmount.")

 def mount(self):
 if not self._is_mounted:
 self._is_mounted = True
 self.component_did_mount()

 def unmount(self):
 if self._is_mounted:
 self._is_mounted = False
 self.component_will_unmount()

# Example of a Component with Lifecycle Methods
class MyComponent(Component):
 def __init__(self, props=None):
 super().__init__(props)
 self.state = {"count": 0}

 def render(self):
 print(f"Rendering MyComponent with props: {self.props} and state: {self.state}")

 def increment(self):
 self.set_state({"count": self.state["count"] + 1})
 print(f"Count incremented: {self.state['count']}")

# Creating and mounting the component
my_component = MyComponent(props={"name": "Test Component"})
my_component.mount() # Trigger the componentDidMount lifecycle method
my_component.render() # Initial render

# Updating the state and triggering the lifecycle method
my_component.increment()
my_component.render()

# Unmounting the component
my_component.unmount() # Trigger componentWillUnmount lifecycle method

# Handling Node Update in a UI Tree
class UIUpdater:
 def __init__(self, root_node):
 self.root_node = root_node

 def update_node(self, old_node, new_node):
 changes = reconcile(old_node, new_node) # Get differences between old and new node
 return apply_reconciliation_changes(old_node, changes) # Apply changes to the node

 def update_ui(self, new_tree):
 self.root_node = self.update_node(self.root_node, new_tree)
 print("UI updated to reflect changes.")

# Event Listener Management
class EventListenerManager:
 def __init__(self):
 self.listeners = {}

 def add_listener(self, target, event_type, listener):
 if target not in self.listeners:
 self.listeners[target] = {}
 if event_type not in self.listeners[target]:
 self.listeners[target][event_type] = []
 self.listeners[target][event_type].append(listener)

 def remove_listener(self, target, event_type, listener):
 if target in self.listeners and event_type in self.listeners[target]:
 self.listeners[target][event_type].remove(listener)
 if not self.listeners[target][event_type]:
 del self.listeners[target][event_type]
 if not self.listeners[target]:
 del self.listeners[target]

 def dispatch_event(self, event):
 if event.target in self.listeners and event.type in self.listeners[event.target]:
 for listener in self.listeners[event.target][event.type]:
 listener(event)
 if event.is_propagation_stopped:
 break

# Handling Task Scheduling and Execution
class TaskScheduler:
 def __init__(self):
 self.task_queue = []

 def schedule_task(self, task, priority=1):
 self.task_queue.append({"task": task, "priority": priority})
 self.task_queue.sort(key=lambda x: x["priority"], reverse=True) # Sort by priority

 def execute_tasks(self):
 while self.task_queue:
 task = self.task_queue.pop(0)["task"]
 task() # Execute the task

# Example usage of TaskScheduler
scheduler = TaskScheduler()

# Schedule tasks with different priorities
scheduler.schedule_task(lambda: print("High priority task"), priority=2)
scheduler.schedule_task(lambda: print("Low priority task"), priority=1)

# Execute the tasks
scheduler.execute_tasks()

# Complete Example and Final Integration with Child Node Update
class MyApp:
 def __init__(self):
 self.scheduler = TaskScheduler()
 self.event_manager = EventListenerManager()
 self.ui_updater = UIUpdater(None) # Initial empty root node
 self.root = Node("View", {"style": "background-color: white"})
 self.ui_updater.root_node = self.root # Set the root node for UI updates

 # Create child nodes and add them to the root
 self.child1 = Node("Text", {"value": "Child 1"})
 self.child2 = Node("Text", {"value": "Child 2"})
 self.root.add_child(self.child1)
 self.root.add_child(self.child2)

 def update_child_node(self, child, new_props):
 # Update the child node's props and trigger a re-render
 print(f"Updating {child.node_type} with new props: {new_props}")
 child.update_props(new_props)
 self.ui_updater.update_ui(self.root) # Reconcile the root to apply changes

 def start(self):
 # Schedule and run tasks
 self.scheduler.schedule_task(lambda: print("App has started"))
 self.scheduler.execute_tasks()

 # Initial UI render
 print("Initial UI Render:")
 self.ui_updater.update_ui(self.root)
 print(f"Root node style: {self.root.props['style']}")

 # Simulate updating the child nodes
 print("\nUpdating child nodes:")
 self.update_child_node(self.child1, {"value": "Updated Child 1"})
 self.update_child_node(self.child2, {"value": "Updated Child 2"})

 # Simulate an event dispatch (just an example)
 event = Event(type="click", target=self.root)
 self.event_manager.add_listener(self.root, "click", lambda e: print(f"Event {e.type} triggered on {e.target.node_type}"))
 self.event_manager.dispatch_event(event)

 print("Current UI Tree in JSON:")
 print(self.root.to_json())

# Running the application
app = MyApp()
app.start()