behaviortree 0.7.4

A #![no_std] compatible behavior tree library similar to 'BehaviorTree.CPP'.
Documentation 
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// Copyright © 2025 Stephan Kunz

//! [`BehaviorTreeObserver`] implementation.

#[cfg(feature = "std")]
extern crate std;

// region:      --- modules
use crate::{
	ConstString, Mutex,
	behavior::{BehaviorState, behavior_data::BehaviorData},
	tree::tree::BehaviorTree,
};
use alloc::{sync::Arc, vec::Vec};
#[cfg(feature = "std")]
use std::time::Instant;
// endregion:   --- modules

// region:      --- Statistics
/// Structure to collect various statistic data.
#[derive(Clone)]
pub struct Statistics {
	/// Last result of a tick, either Success or Failure.
	pub last_result: BehaviorState,
	/// Last state. Can be any state.
	pub current_state: BehaviorState,
	/// count state transitions, excluding transition to Idle.
	pub transitions_count: usize,
	/// count number of transitions to Success.
	pub success_count: usize,
	/// count number of transitions to Failure.
	pub failure_count: usize,
	/// count number of transitions to Skip.
	pub skip_count: usize,
	/// Duration of execution
	#[cfg(feature = "std")]
	pub timestamp: Instant,
}

impl Default for Statistics {
	fn default() -> Self {
		Self {
			last_result: BehaviorState::default(),
			current_state: BehaviorState::default(),
			transitions_count: Default::default(),
			success_count: Default::default(),
			failure_count: Default::default(),
			skip_count: Default::default(),
			#[cfg(feature = "std")]
			timestamp: Instant::now(),
		}
	}
}

impl Statistics {
	fn reset(&mut self) {
		self.last_result = BehaviorState::default();
		self.current_state = BehaviorState::default();
		self.transitions_count = Default::default();
		self.success_count = Default::default();
		self.failure_count = Default::default();
		self.skip_count = Default::default();
		#[cfg(feature = "std")]
		{
			self.timestamp = Instant::now();
		}
	}
}
// endregion:   --- Statistics

// region:      --- BehaviorTreeObserver
/// An observer collecting [`BehaviorTree`] statistics
pub struct BehaviorTreeObserver {
	/// The shared statistics data
	statistics: Arc<Mutex<Vec<Statistics>>>,
}

impl BehaviorTreeObserver {
	/// Construct a new [`BehaviorTreeObserver`].
	pub fn new(root: &mut BehaviorTree) -> Self {
		let id: ConstString = "statistics".into();
		let statistics: Arc<Mutex<Vec<Statistics>>> = Arc::new(Mutex::new(Vec::new()));

		// add a statistics entry and a callback for each tree element
		for element in root.iter_mut() {
			statistics.lock().push(Statistics::default());
			let statistics_clone: Arc<Mutex<Vec<Statistics>>> = statistics.clone();
			// the callback
			let callback = move |behavior: &BehaviorData, new_state: &mut BehaviorState| {
				let mut stats = statistics_clone.lock();
				let entry = &mut stats[behavior.uid() as usize];
				entry.transitions_count += 1;
				match new_state {
					BehaviorState::Failure => {
						entry.failure_count += 1;
						entry.last_result = *new_state;
					}
					BehaviorState::Idle | BehaviorState::Running => {}
					BehaviorState::Skipped => entry.skip_count += 1,
					BehaviorState::Success => {
						entry.success_count += 1;
						entry.last_result = *new_state;
					}
				}
				entry.current_state = *new_state;
				#[cfg(feature = "std")]
				{
					entry.timestamp = Instant::now();
				}
				drop(stats);
			};
			element.add_pre_state_change_callback(id.clone(), callback);
		}
		Self { statistics }
	}

	/// Get the [`Statistics`] for a [`BehaviorTreeElement`](crate::tree::tree_element::BehaviorTreeElement) using its uid.
	#[must_use]
	pub fn get_statistics(&self, uid: u16) -> Option<Statistics> {
		if self.statistics.lock().len() >= uid as usize {
			return Some((self.statistics.lock()[uid as usize]).clone());
		}
		None
	}

	/// Reset the [`BehaviorTreeObserver`].
	pub fn reset(&self) {
		for stats in &mut (*self.statistics.lock()) {
			stats.reset();
		}
	}
}
// endregion:   --- BehaviorTreeObserver