Crate dptree

An implementation of the chain (tree) of responsibility pattern.

[examples/web_server.rs]

use dptree::prelude::*;

type WebHandler = Endpoint<'static, String>;

#[rustfmt::skip]
#[tokio::main]
async fn main() {
    let web_server = dptree::entry()
        .branch(smiles_handler())
        .branch(sqrt_handler())
        .branch(not_found_handler());
     
    assert_eq!(
        web_server.dispatch(dptree::deps!["/smile"]).await,
        ControlFlow::Break("🙃".to_owned())
    );
    assert_eq!(
        web_server.dispatch(dptree::deps!["/sqrt 16"]).await,
        ControlFlow::Break("4".to_owned())
    );
    assert_eq!(
        web_server.dispatch(dptree::deps!["/lol"]).await,
        ControlFlow::Break("404 Not Found".to_owned())
    );
}

fn smiles_handler() -> WebHandler {
    dptree::filter(|req: &'static str| req.starts_with("/smile"))
        .endpoint(|| async { "🙃".to_owned() })
}

fn sqrt_handler() -> WebHandler {
    dptree::filter_map(|req: &'static str| {
        if req.starts_with("/sqrt") {
            let (_, n) = req.split_once(' ')?;
            n.parse::<f64>().ok()
        } else {
            None
        }
    })
    .endpoint(|n: f64| async move { format!("{}", n.sqrt()) })
}

fn not_found_handler() -> WebHandler {
    dptree::endpoint(|| async { "404 Not Found".to_owned() })
}

For a high-level overview, please see README.md.

Modules

description

Built-in handler description types.

di

An implementation of dependency injection.

prelude

Commonly used items.

Macros

case

Filters an enumeration, passing its payload forwards.

deps

Constructs DependencyMap with a list of dependencies.

Structs

Handler

An instance that receives an input and decides whether to break a chain or pass the value further.

Type

A run-time representation of a type. Used only for run-time type inference and checking of handler chains.

Enums

HandlerSignature

A run-time handler signature. Used only for run-time type inference and checking of handler chains.

Traits

HandlerDescription

Handler description.

Functions

endpoint

Constructs a handler that has no further handlers in a chain.

entry

Constructs an entry point handler.

filter

Constructs a handler that filters input with the predicate pred.

filter_async

The asynchronous version of filter.

filter_async_with_description

filter_async with a custom description.

filter_map

Constructs a handler that optionally passes a value of a new type further.

filter_map_async

The asynchronous version of filter_map.

filter_map_async_with_description

filter_map_async with a custom description.

filter_map_with_description

filter_map with a custom description.

filter_with_description

filter with a custom description.

from_fn

Constructs a handler from a function.

from_fn_with_description

from_fn with a custom description.

inspect

Constructs a handler that inspects current state. Like map but does not add return value of f to the container.

inspect_async

The asynchronous version of inspect.

inspect_async_with_description

inspect_async with a custom description.

inspect_with_description

inspect with a custom description.

map

Constructs a handler that passes a value of a new type further.

map_async

The asynchronous version of map.

map_async_with_description

map_async with a custom description.

map_with_description

map with a custom description.

type_check

Performs run-time type checking.

Type Aliases

Cont

A continuation representing the rest of a handler chain.

Endpoint

A handler with no further handlers in a chain.

HandlerResult

An output type produced by a handler.