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playground.rs

#![feature(pattern)]

use std::str::pattern::Pattern;
use std::marker::PhantomData;

#[derive(PartialEq, Eq)]
enum Method {
    Get,
    Post,
    Put,
    Head,
}

struct Req<'a> {
    method: Method,
    location: &'a str,
    content: &'a str,
}

#[derive(Debug)]
struct Resp(u16);

trait Handler<'a, Context> {
    fn handle(&'a self, c: Context, req: &'a Req<'a>) -> Option<Resp>;
}

struct Router<P, H, C=()>(Method, P, H, PhantomData<C>);
struct Chain<A, B, C=()>(A, B, PhantomData<C>);

impl<
    'a,
    C: Clone,
    A: Handler<'a, C>,
    B: Handler<'a, C>
> Handler<'a, C> for Chain<A, B, C> {
    fn handle(&'a self, c: C, req: &'a Req<'a>) -> Option<Resp> {
        let c_clone = c.clone();
        self.0.handle(c, req).or_else(|| self.1.handle(c_clone, req))
    }
}

impl<
    'a,
    C,
    P: Pattern<'a> + Clone,
    H: Handler<'a, C>
> Router<P, H, C> {
    fn new(m: Method, p: P, h: H) -> Self {
        Router(m, p, h, PhantomData)
    }
    
    fn get(p: P, h: H) -> Self {
        Self::new(Method::Get, p, h)
    }
}

impl<'a, C, A: Handler<'a, C>, B: Handler<'a, C>> Chain<A, B, C> {
    fn new(a: A, b: B) -> Chain<A, B, C> {
        Chain(a, b, PhantomData)
    }
}

trait HandleOr<'a, C>: Sized + Handler<'a, C> {
    fn or_else<Other: Handler<'a, C>>(
        self,
        other: Other
    ) -> Chain<Self, Other, C> {
        Chain::new(self, other)
    }
    
    fn or_new<
        OP: Pattern<'a> + Clone, OH: Handler<'a, C>
    >(
        self,
        m: Method,
        p: OP,
        h: OH
    ) -> Chain<Self, Router<OP, OH, C>, C> {
        self.or_else(Router::new(m, p, h))
    }
    
    fn or_get<
        OP: Pattern<'a> + Clone, OH: Handler<'a, C>
    >(
        self,
        p: OP,
        h: OH
    ) -> Chain<Self, Router<OP, OH, C>, C> {
        self.or_else(Router::get(p, h))
    }
}

impl<'a, C, H: Handler<'a, C>> HandleOr<'a, C> for H { }

impl<
    'a,
    C,
    P: Pattern<'a> + Clone,
    H: Handler<'a, C>
> Handler<'a, C> for Router<P, H, C> {
    fn handle(&'a self, c: C, req: &'a Req<'a>) -> Option<Resp> {
        if req.method == self.0 && req.location.contains(self.1.clone()) {
            self.2.handle(c, req)
        } else {
            None
        }
    }
}

impl<
    'a,
    C:,
    F: Fn(C, &'a Req<'a>) -> Option<Resp>
> Handler<'a, C> for F {
    fn handle(&'a self, c: C, req: &'a Req<'a>) -> Option<Resp> {
        self(c, req)
    }
}

fn main() {
    println!(
        "{:?}",
        Router::get("/test", |(), _| Some(Resp(200)))
            .or_get("/something_else", |(), _| Some(Resp(100)))
            .or_get("/last_thing", |(), _| Some(Resp(404)))
            .handle(
                (),
                &Req {
                    method: Method::Get,
                    location: "/last_thing",
                    content: "Hello!",
                }
            )
    );
}