hamon 0.1.1

A zero-cost, type-level static decorator and pipeline builder.
Documentation 
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use crate::Decorator;

pub struct ConditionDecorator<D, P> {
    decorator: D,
    pred: P,
}

impl<T, D, P> Decorator<T, T> for ConditionDecorator<D, P>
where
    D: Decorator<T, T>,
    P: FnMut(&T) -> bool,
{
    fn produce(&mut self, input: T) -> T {
        if (self.pred)(&input) {
            self.decorator.produce(input)
        } else {
            input
        }
    }
}

/// A trait extends the optional validation on the decorator being declared
///
/// It's the extension so the usage of it falls entirely on your hands. Once, you have imported this trait
/// any registered decorators can only take effect if the condition applies on it evaluated to True
pub trait DecoratorExt<T>: Decorator<T, T> {
    /// Combine the condition with the current decorator. Later when it's being consumed via `step` or `build`
    /// The determination of wrap up with the existing decorator is the result of the Predicate.
    fn when<P>(self, pred: P) -> ConditionDecorator<Self, P>
    where
        P: FnMut(&T) -> bool,
        Self: Sized,
    {
        ConditionDecorator {
            decorator: self,
            pred,
        }
    }
}

impl<F: Decorator<T, T>, T> DecoratorExt<T> for F {}