bhv 0.4.0

A crate providing means to create and use Behavior Trees
Documentation 
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use std::marker::PhantomData;

#[allow(unused_imports)]
use crate::events_impl::{
    core::{Bhv, Status},
    events::{Event, UnitEventPump},
};

/// The type of the result of [`action`].
#[derive(Clone)]
pub struct Action<A, C>(A, PhantomData<C>)
    where
        A: FnMut(&mut C);

/// The type of the result of [`cond`].
#[derive(Clone)]
pub struct Cond<P, C>(P, PhantomData<C>)
    where
        P: Fn(&C) -> bool;

/// The type of the result of [`async_action`].
#[derive(Clone)]
pub struct AsyncAction<A, C>(A, PhantomData<C>)
    where A: FnMut(&mut C) -> Status;

impl<A, C> Bhv for Action<A, C>
    where A: FnMut(&mut C) {
    type Context = C;
    #[inline]
    fn react(&mut self, _event: &dyn Event, ctx: &mut Self::Context) -> Status {
        self.0(ctx);
        Status::Success
    }
}

impl<P, C> Bhv for Cond<P, C>
    where P: Fn(&C) -> bool {
    type Context = C;
    #[inline]
    fn react(&mut self, _event: &dyn Event, ctx: &mut Self::Context) -> Status {
        if self.0(ctx) {
            Status::Success
        } else {
            Status::Failure
        }
    }
}

impl<A, C> Bhv for AsyncAction<A, C>
    where A: FnMut(&mut C) -> Status {
    type Context = C;
    #[inline]
    fn react(&mut self, _event: &dyn Event, ctx: &mut Self::Context) -> Status {
        self.0(ctx)
    }
}


/// Adapt a function that returns nothing into a behavior, returning [`Status::Success`]
/// on every call to [`Bhv::react`].
///
/// # Example
///
/// ```
/// use bhv::*;
///
/// let print = action(|v| println!("Value is {}", *v));
/// print.execute(UnitEventPump, &mut 42);
/// ```
#[inline]
pub fn action<A, C>(a: A) -> Action<A, C>
    where A: FnMut(&mut C) { Action(a, PhantomData) }

/// Adapt a predicate into a behavior, returning [`Status::Success`] if
/// the predicate returns `true` and [`Status::Failure`] otherwise.
///
/// # Example
///
/// ```
/// use bhv::*;
///
/// let check = sel! {
///     seq! {
///         cond(|v| *v >= 10),
///         action(|_| println!("v >= 10")),
///     },
///     action(|_| println!("v < 10")),
/// };
///
/// check.execute(UnitEventPump, &mut 10);
/// ```
#[inline]
pub fn cond<P, C>(p: P) -> Cond<P, C>
    where P: Fn(&C) -> bool { Cond(p, PhantomData) }


/// Wrap a function returning a [`crate::Status`] into a behavior.
///
/// # Example
///
/// ```
/// use bhv::*;
///
/// struct State {
///     a: i32,
///     b: i32,
///     n: i32,
/// }
///
/// impl State {
///     fn new(steps: i32) -> Self {
///         Self { a: 0, b: 1, n: steps }
///     }
/// }
///
/// let mut state = State::new(10); // show first 10 fibonacci numbers
///
/// let code = async_action(|s: &mut State| {
///     if s.n == 0 {
///         Status::Success
///     } else {
///         print!("{} ", s.b);
///         let tmp = s.b;
///         s.b += s.a;
///         s.a = tmp;
///
///         s.n -= 1;
///         Status::Running
///     }
/// });
///
/// code.execute(UnitEventPump, &mut state);
///
/// assert_eq!(state.b, 89);
/// ```
#[inline]
pub fn async_action<A, C>(a: A) -> AsyncAction<A, C>
    where A: FnMut(&mut C) -> Status { AsyncAction(a, PhantomData) }