Struct Deferred 

pub struct Deferred<S> { /* private fields */ }

Struct that holds parts and state of deferred logic to execute whenever you want to.

Note

Everytime when you want to resume execution, you consume deferred context and produce new one so keep in mind to restore it before resume() and store it again after resume().

Implementations

impl<S> Deferred<S>

pub fn new(state: S, parts: Vec<Part<S>>) -> Self

Creates new deferred execution.

Arguments

• state - context initial state.
• parts - vector of logic parts.

Example

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| state!(c.state() + 2)
    ])
}

assert_eq!(foo(1).consume(), 4);

pub fn can_resume(&self) -> bool

Tells if deferred execution can be resumed.

Example

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| state!(c.state() + 2)
    ])
}

let d = foo(1);
assert_eq!(d.can_resume(), true);
let d = d.resume().unwrap();
assert_eq!(d.can_resume(), true);
let d = d.resume().unwrap();
assert_eq!(d.can_resume(), false);

pub fn state(&self) -> Option<&S>

Gets reference to current state stored in context.

Example

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| state!(c.state() + 2)
    ])
}

let d = foo(1);
assert_eq!(d.state(), Some(&1));
let d = d.resume().unwrap();
assert_eq!(d.state(), Some(&2));
let d = d.resume().unwrap();
assert_eq!(d.state(), Some(&4));

pub fn resume(self) -> Option<Self>

Resumes deferred execution, which means we execute next logic part and store its state.

Note

While you resume execution, you consume it and return new one so keep in mind that you need to store it again or replace with old one after calling resume().

Example

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| foo2(c.state()).into(),
        |c| state!(c.state() + 2)
    ])
}

fn foo2(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() * 2),
        |c| state!(c.state() * 3)
    ])
}

let d = foo(1);
assert!(d.can_resume());
assert_eq!(d.state(), Some(&1));

let d = d.resume().unwrap();
assert!(d.can_resume());
assert_eq!(d.state(), Some(&2));

let d = d.resume().unwrap();
assert!(d.can_resume());
assert_eq!(d.state(), Some(&4));

let d = d.resume().unwrap();
assert!(d.can_resume());
assert_eq!(d.state(), Some(&12));

let d = d.resume().unwrap();
assert!(!d.can_resume());
assert_eq!(d.state(), Some(&14));

pub fn consume(self) -> S

Consumes deferred execution, which means we execute all remaining logic parts and returns final state.

Example

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| state!(c.state() + 2)
    ])
}

assert_eq!(foo(1).consume(), 4);

pub fn unwrap(self) -> S

Alias for consume() method.

Trait Implementations

impl<S> Into<Context<S>> for Deferred<S>

fn into(self) -> Context<S>

Converts this type into the (usually inferred) input type.