Trait portal::Filter

pub trait Filter: FilterBase {
    fn and<F>(self, other: F) -> And<Self, F>
    where
        Self: Sized,
        <Self::Extract as Tuple>::HList: Combine<<F::Extract as Tuple>::HList>,
        F: Filter + Clone,
        F::Error: CombineRejection<Self::Error>,
    { ... }
    fn or<F>(self, other: F) -> Or<Self, F>
    where
        Self: Filter<Error = Rejection> + Sized,
        F: Filter,
        F::Error: CombineRejection<Self::Error>,
    { ... }
    fn map<F>(self, fun: F) -> Map<Self, F>
    where
        Self: Sized,
        F: Func<Self::Extract> + Clone,
    { ... }
    fn and_then<F>(self, fun: F) -> AndThen<Self, F>
    where
        Self: Sized,
        F: Func<Self::Extract> + Clone,
        F::Output: TryFuture + Send,
        <F::Output as TryFuture>::Error: CombineRejection<Self::Error>,
    { ... }
    fn or_else<F>(self, fun: F) -> OrElse<Self, F>
    where
        Self: Filter<Error = Rejection> + Sized,
        F: Func<Rejection>,
        F::Output: TryFuture<Ok = Self::Extract> + Send,
        <F::Output as TryFuture>::Error: IsReject,
    { ... }
    fn recover<F>(self, fun: F) -> Recover<Self, F>
    where
        Self: Filter<Error = Rejection> + Sized,
        F: Func<Rejection>,
        F::Output: TryFuture + Send,
        <F::Output as TryFuture>::Error: IsReject,
    { ... }
    fn unify<T>(self) -> Unify<Self>
    where
        Self: Filter<Extract = (Either<T, T>,)> + Sized,
        T: Tuple,
    { ... }
    fn untuple_one<T>(self) -> UntupleOne<Self>
    where
        Self: Filter<Extract = (T,)> + Sized,
        T: Tuple,
    { ... }
    fn with<W>(self, wrapper: W) -> W::Wrapped
    where
        Self: Sized,
        W: Wrap<Self>,
    { ... }
    fn boxed(self) -> BoxedFilter<Self::Extract>
    where
        Self: Sized + Send + Sync + 'static,
        Self::Extract: Send,
        Self::Error: Into<Rejection>,
    { ... }
}

Composable request filters.

A Filter can optionally extract some data from a request, combine it with others, mutate it, and return back some value as a reply. The power of Filters come from being able to isolate small subsets, and then chain and reuse them in various parts of your app.

Extracting Tuples

You may notice that several of these filters extract some tuple, often times a tuple of just 1 item! Why?

If a filter extracts a (String,), that simply means that it extracts a String. If you were to map the filter, the argument type would be exactly that, just a String.

What is it? It's just some type magic that allows for automatic combining and flattening of tuples. Without it, combining two filters together with and, where one extracted (), and another String, would mean the map would be given a single argument of ((), String,), which is just no fun.

Provided methods

fn and<F>(self, other: F) -> And<Self, F> where
    Self: Sized,
    <Self::Extract as Tuple>::HList: Combine<<F::Extract as Tuple>::HList>,
    F: Filter + Clone,
    F::Error: CombineRejection<Self::Error>, 

Composes a new Filter that requires both this and the other to filter a request.

Additionally, this will join together the extracted values of both filters, so that map and and_then receive them as separate arguments.

If a Filter extracts nothing (so, ()), combining with any other filter will simply discard the (). If a Filter extracts one or more items, combining will mean it extracts the values of itself combined with the other.

Example

use portal::Filter;

// Match `/hello/:name`...
portal::path("hello")
    .and(portal::path::param::<String>());

fn or<F>(self, other: F) -> Or<Self, F> where
    Self: Filter<Error = Rejection> + Sized,
    F: Filter,
    F::Error: CombineRejection<Self::Error>, 

Composes a new Filter of either this or the other filter.

Example

use std::net::SocketAddr;
use portal::Filter;

// Match either `/:u32` or `/:socketaddr`
portal::path::param::<u32>()
    .or(portal::path::param::<SocketAddr>());

fn map<F>(self, fun: F) -> Map<Self, F> where
    Self: Sized,
    F: Func<Self::Extract> + Clone, 

Composes this Filter with a function receiving the extracted value.

Example

use portal::Filter;

// Map `/:id`
portal::path::param().map(|id: u64| {
  format!("Hello #{}", id)
});

Func

The generic Func trait is implemented for any function that receives the same arguments as this Filter extracts. In practice, this shouldn't ever bother you, and simply makes things feel more natural.

For example, if three Filters were combined together, suppose one extracts nothing (so ()), and the other two extract two integers, a function that accepts exactly two integer arguments is allowed. Specifically, any Fn(u32, u32).

Without Product and Func, this would be a lot messier. First of all, the ()s couldn't be discarded, and the tuples would be nested. So, instead, you'd need to pass an Fn(((), (u32, u32))). That's just a single argument. Bleck!

Even worse, the tuples would shuffle the types around depending on the exact invocation of ands. So, unit.and(int).and(int) would result in a different extracted type from unit.and(int.and(int), or from int.and(unit).and(int). If you changed around the order of filters, while still having them be semantically equivalent, you'd need to update all your maps as well.

Product, HList, and Func do all the heavy work so that none of this is a bother to you. What's more, the types are enforced at compile-time, and tuple flattening is optimized away to nothing by LLVM.

fn and_then<F>(self, fun: F) -> AndThen<Self, F> where
    Self: Sized,
    F: Func<Self::Extract> + Clone,
    F::Output: TryFuture + Send,
    <F::Output as TryFuture>::Error: CombineRejection<Self::Error>, 

Composes this Filter with a function receiving the extracted value.

The function should return some TryFuture type.

The Error type of the return Future needs be a Rejection, which means most futures will need to have their error mapped into one.

Example

use portal::Filter;

// Validate after `/:id`
portal::path::param().and_then(|id: u64| async move {
    if id != 0 {
        Ok(format!("Hello #{}", id))
    } else {
        Err(portal::reject::not_found())
    }
});

fn or_else<F>(self, fun: F) -> OrElse<Self, F> where
    Self: Filter<Error = Rejection> + Sized,
    F: Func<Rejection>,
    F::Output: TryFuture<Ok = Self::Extract> + Send,
    <F::Output as TryFuture>::Error: IsReject, 

Compose this Filter with a function receiving an error.

The function should return some TryFuture type yielding the same item and error types.

fn recover<F>(self, fun: F) -> Recover<Self, F> where
    Self: Filter<Error = Rejection> + Sized,
    F: Func<Rejection>,
    F::Output: TryFuture + Send,
    <F::Output as TryFuture>::Error: IsReject, 

Compose this Filter with a function receiving an error and returning a new type, instead of the same type.

This is useful for "customizing" rejections into new response types. See also the rejections example.

fn unify<T>(self) -> Unify<Self> where
    Self: Filter<Extract = (Either<T, T>,)> + Sized,
    T: Tuple, 

Unifies the extracted value of Filters composed with or.

When a Filter extracts some Either<T, T>, where both sides are the same type, this combinator can be used to grab the inner value, regardless of which side of Either it was. This is useful for values that could be extracted from multiple parts of a request, and the exact place isn't important.

Example

use std::net::SocketAddr;
use portal::Filter;

let client_ip = portal::header("x-real-ip")
    .or(portal::header("x-forwarded-for"))
    .unify()
    .map(|ip: SocketAddr| {
        // Get the IP from either header,
        // and unify into the inner type.
    });

fn untuple_one<T>(self) -> UntupleOne<Self> where
    Self: Filter<Extract = (T,)> + Sized,
    T: Tuple, 

Convenience method to remove one layer of tupling.

This is useful for when things like map don't return a new value, but just (), since portal will wrap it up into a ((),).

Example

use portal::Filter;

let route = portal::path::param()
    .map(|num: u64| {
        println!("just logging: {}", num);
        // returning "nothing"
    })
    .untuple_one()
    .map(|| {
        println!("the ((),) was removed");
        portal::reply()
    });

use portal::Filter;

let route = portal::any()
    .map(|| {
        // wanting to return a tuple
        (true, 33)
    })
    .untuple_one()
    .map(|is_enabled: bool, count: i32| {
        println!("untupled: ({}, {})", is_enabled, count);
    });

fn with<W>(self, wrapper: W) -> W::Wrapped where
    Self: Sized,
    W: Wrap<Self>, 

Wraps the current filter with some wrapper.

The wrapper may do some preparation work before starting this filter, and may do post-processing after the filter completes.

Example

use portal::Filter;

let route = portal::any()
    .map(portal::reply);

// Wrap the route with a log wrapper.
let route = route.with(portal::log("example"));

fn boxed(self) -> BoxedFilter<Self::Extract> where
    Self: Sized + Send + Sync + 'static,
    Self::Extract: Send,
    Self::Error: Into<Rejection>, 

Boxes this filter into a trait object, making it easier to name the type.

Example

use portal::Filter;

fn impl_reply() -> portal::filters::BoxedFilter<(impl portal::Reply,)> {
    portal::any()
        .map(portal::reply)
        .boxed()
}

fn named_i32() -> portal::filters::BoxedFilter<(i32,)> {
    portal::path::param::<i32>()
        .boxed()
}

fn named_and() -> portal::filters::BoxedFilter<(i32, String)> {
    portal::path::param::<i32>()
        .and(portal::header::<String>("host"))
        .boxed()
}

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Implementors

impl<T: FilterBase> Filter for T

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