bhv 0.4.0

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

use crate::{Bhv, Status};

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

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

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

/// Adapt a predicate into a behavior, returning [`Status::Success`] if
/// the predicate returns `true` and [`Status::Failure`] otherwise.
///
/// # Example
///
/// ```
/// use bhv::*;
///
/// let check = cond(|v| *v >= 10);
///
/// assert_eq!(check.clone().execute(&mut 10), true);
/// assert_eq!(check.execute(&mut 5), false);
/// ```
#[inline]
pub fn cond<Ctx, C>(c: C) -> Cond<Ctx, C>
    where
        C: Fn(&Ctx) -> bool,
{
    Cond(c, PhantomData)
}

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

/// Wrap a function returning a [`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(&mut state);
///
/// assert_eq!(state.b, 89);
/// ```
#[inline]
pub fn async_action<Ctx, A>(a: A) -> AsyncAction<Ctx, A>
    where A: FnMut(&mut Ctx) -> Status { AsyncAction(a, PhantomData) }

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

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

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