Struct ArcSupplier 

pub struct ArcSupplier<T> { /* private fields */ }

Thread-safe shared ownership stateless supplier.

Uses Arc<dyn Fn() -> T + Send + Sync> for thread-safe shared ownership. Lock-free - no Mutex needed! Can be cloned and sent across threads with excellent concurrent performance.

Ownership Model

Methods borrow &self instead of consuming self. The original supplier remains usable after method calls:

use qubit_function::{ArcSupplier, Supplier};

let source = ArcSupplier::new(|| 10);
let mapped = source.map(|x| x * 2);
// source is still usable here!

Lock-Free Performance

Unlike ArcStatefulSupplier, this implementation doesn’t need Mutex. Multiple threads can call get() concurrently without lock contention, making it ideal for high-concurrency scenarios.

Examples

Thread-safe Factory

use qubit_function::{ArcSupplier, Supplier};
use std::thread;

let factory = ArcSupplier::new(|| {
    String::from("Hello")
});

let f1 = factory.clone();
let f2 = factory.clone();

let h1 = thread::spawn(move || f1.get());
let h2 = thread::spawn(move || f2.get());

assert_eq!(h1.join().unwrap(), "Hello");
assert_eq!(h2.join().unwrap(), "Hello");

Reusable Transformations

use qubit_function::{ArcSupplier, Supplier};

let base = ArcSupplier::new(|| 10);
let doubled = base.map(|x| x * 2);
let tripled = base.map(|x| x * 3);

// All remain usable
assert_eq!(base.get(), 10);
assert_eq!(doubled.get(), 20);
assert_eq!(tripled.get(), 30);

Author

Haixing Hu

Implementations

impl<T> ArcSupplier<T>

pub fn new<F>(f: F) -> Self

where F: Fn() -> T + Send + Sync + 'static,

Creates a new supplier.

Wraps the provided closure in the appropriate smart pointer type for this supplier implementation.

Examples found in repository

examples/suppliers/stateful_supplier_demo.rs (line 157)

fn demo_arc_supplier() {
    println!("--- ArcSupplier ---");

    // Basic usage (Fn)
    let supplier = ArcSupplier::new(|| 42);
    let s = supplier;
    println!("Basic: {}", s.get());

    // Reusable transformations (Fn)
    let source = ArcSupplier::new(|| 10);
    let doubled = source.map(|x| x * 2);
    let tripled = source.map(|x| x * 3);

    let s = source;
    let d = doubled;
    let t = tripled;
    println!("Source: {}", s.get());
    println!("Doubled: {}", d.get());
    println!("Tripled: {}", t.get());

    // Stateful with ArcStatefulSupplier (FnMut)
    let call_count = Arc::new(Mutex::new(0));
    let call_count_clone = Arc::clone(&call_count);
    let source = ArcStatefulSupplier::new(move || {
        let mut c = call_count_clone.lock().unwrap();
        *c += 1;
        println!("  Computation #{}", *c);
        42
    });

    // Memoization with ArcStatefulSupplier
    let memoized = source.memoize();
    let mut m = memoized;
    println!("First call: {}", m.get());
    println!("Second call (cached): {}", m.get());
    println!("Call count: {}", *call_count.lock().unwrap());
    println!();
}

fn demo_arc_supplier_threading() {
    println!("--- ArcStatefulSupplier Threading ---");

    let counter = Arc::new(Mutex::new(0));
    let counter_clone = Arc::clone(&counter);

    let supplier = ArcStatefulSupplier::new(move || {
        let mut c = counter_clone.lock().unwrap();
        *c += 1;
        *c
    });

    let mut s1 = supplier.clone();
    let mut s2 = supplier.clone();
    let mut s3 = supplier;

    let h1 = thread::spawn(move || {
        let v1 = s1.get();
        let v2 = s1.get();
        println!("Thread 1: {} {}", v1, v2);
        (v1, v2)
    });

    let h2 = thread::spawn(move || {
        let v1 = s2.get();
        let v2 = s2.get();
        println!("Thread 2: {} {}", v1, v2);
        (v1, v2)
    });

    let v1 = s3.get();
    let v2 = s3.get();
    println!("Main thread: {} {}", v1, v2);

    h1.join().unwrap();
    h2.join().unwrap();

    println!("Final counter: {}", *counter.lock().unwrap());
    println!();
}

fn demo_rc_supplier() {
    println!("--- RcSupplier ---");

    // Basic usage (Fn)
    let supplier = RcSupplier::new(|| 42);
    let s = supplier;
    println!("Basic: {}", s.get());

    // Shared state (FnMut) - use RcStatefulSupplier
    let counter = Rc::new(RefCell::new(0));
    let counter_clone = Rc::clone(&counter);
    let supplier = RcStatefulSupplier::new(move || {
        let mut c = counter_clone.borrow_mut();
        *c += 1;
        *c
    });

    let mut s1 = supplier.clone();
    let mut s2 = supplier.clone();

    println!("First clone: {}", s1.get());
    println!("Second clone: {}", s2.get());
    println!("First clone again: {}", s1.get());

    // Reusable transformations (Fn)
    let source = RcSupplier::new(|| 10);
    let doubled = source.map(|x| x * 2);
    let tripled = source.map(|x| x * 3);
    let squared = source.map(|x| x * x);

    let s = source;
    let d = doubled;
    let t = tripled;
    let sq = squared;

    println!("Source: {}", s.get());
    println!("Doubled: {}", d.get());
    println!("Tripled: {}", t.get());
    println!("Squared: {}", sq.get());
    println!();
}

fn demo_type_conversions() {
    println!("--- Type Conversions ---");

    // Closure to Box (Fn)
    let closure = || 42;
    let boxed = Supplier::into_box(closure);
    println!("Closure -> Box: {}", boxed.get());

    // Closure to Rc (Fn)
    let closure = || 100;
    let rc = Supplier::into_rc(closure);
    println!("Closure -> Rc: {}", rc.get());

    // Closure to Arc (Fn)
    let closure = || 200;
    let arc = Supplier::into_arc(closure);
    println!("Closure -> Arc: {}", arc.get());

    // Box to Rc (Fn)
    let boxed = BoxSupplier::new(|| 42);
    let rc = boxed.into_rc();
    println!("Box -> Rc: {}", rc.get());

    // Arc to Box (Fn)
    let arc = ArcSupplier::new(|| 42);
    let boxed = arc.into_box();
    println!("Arc -> Box: {}", boxed.get());

    // Rc to Box (Fn)
    let rc = RcSupplier::new(|| 42);
    let boxed = rc.into_box();
    println!("Rc -> Box: {}", boxed.get());

    println!();
}

pub fn new_with_name<F>(name: &str, f: F) -> Self

where F: Fn() -> T + Send + Sync + 'static,

Creates a new named supplier.

Wraps the provided closure and assigns it a name, which is useful for debugging and logging purposes.

pub fn new_with_optional_name<F>(f: F, name: Option<String>) -> Self

where F: Fn() -> T + Send + Sync + 'static,

Creates a new named supplier with an optional name.

Wraps the provided closure and assigns it an optional name.

pub fn name(&self) -> Option<&str>

Gets the name of this supplier.

Returns

Returns Some(&str) if a name was set, None otherwise.

pub fn set_name(&mut self, name: &str)

Sets the name of this supplier.

Parameters

• name - The name to set for this supplier

pub fn clear_name(&mut self)

Clears the name of this supplier.

pub fn map<U, M>(&self, mapper: M) -> ArcSupplier<U>

where T: 'static, M: Transformer<T, U> + Send + Sync + 'static, U: 'static,

Maps the output using a transformation function.

Parameters

• mapper - The transformation function to apply

Returns

A new $struct_name<U> with the mapped output

Examples

use qubit_function::{ArcSupplier, Supplier};

let source = ArcSupplier::new(|| 10);
let mapped = source.map(|x| x * 2);
// source is still usable
assert_eq!(mapped.get(), 20);

Examples found in repository

examples/suppliers/stateful_supplier_demo.rs (line 163)

fn demo_arc_supplier() {
    println!("--- ArcSupplier ---");

    // Basic usage (Fn)
    let supplier = ArcSupplier::new(|| 42);
    let s = supplier;
    println!("Basic: {}", s.get());

    // Reusable transformations (Fn)
    let source = ArcSupplier::new(|| 10);
    let doubled = source.map(|x| x * 2);
    let tripled = source.map(|x| x * 3);

    let s = source;
    let d = doubled;
    let t = tripled;
    println!("Source: {}", s.get());
    println!("Doubled: {}", d.get());
    println!("Tripled: {}", t.get());

    // Stateful with ArcStatefulSupplier (FnMut)
    let call_count = Arc::new(Mutex::new(0));
    let call_count_clone = Arc::clone(&call_count);
    let source = ArcStatefulSupplier::new(move || {
        let mut c = call_count_clone.lock().unwrap();
        *c += 1;
        println!("  Computation #{}", *c);
        42
    });

    // Memoization with ArcStatefulSupplier
    let memoized = source.memoize();
    let mut m = memoized;
    println!("First call: {}", m.get());
    println!("Second call (cached): {}", m.get());
    println!("Call count: {}", *call_count.lock().unwrap());
    println!();
}

pub fn filter<P>(&self, predicate: P) -> ArcSupplier<Option<T>>

where T: 'static, P: Predicate<T> + Send + Sync + 'static,

Filters output based on a predicate.

Parameters

• predicate - The predicate to test the supplied value

Returns

A new filtered $struct_name<Option<$t>>

Examples

use qubit_function::{ArcSupplier, Supplier};

let source = ArcSupplier::new(|| 42);
let filtered = source.filter(|x: &i32| x % 2 == 0);

assert_eq!(filtered.get(), Some(42));

pub fn zip<U, S>(&self, other: S) -> ArcSupplier<(T, U)>

where T: 'static, S: Supplier<U> + Send + Sync + 'static, U: 'static,

Combines this supplier with another, producing a tuple.

Parameters

• other - The other supplier to combine with

Returns

A new $struct_name<($t, U)>

Examples

use qubit_function::{ArcSupplier, Supplier};

let first = ArcSupplier::new(|| 42);
let second = ArcSupplier::new(|| "hello");

let zipped = first.zip(second);

assert_eq!(zipped.get(), (42, "hello"));

impl<T> ArcSupplier<T>

pub fn constant(value: T) -> Self

where T: Clone + Send + Sync + 'static,

Creates a supplier that returns a constant value.

Creates a supplier that always returns the same value. Useful for default values or placeholder implementations.

Note: This method requires T: Sync because the constant value is captured by a Fn closure which needs to be Sync for Arc.

Parameters

• value - The constant value to return

Returns

Returns a new supplier instance that returns the constant value.

Examples

use qubit_function::{ArcSupplier, Supplier};

let supplier = ArcSupplier::constant(42);
assert_eq!(supplier.get(), 42);
assert_eq!(supplier.get(), 42); // Can be called multiple times

Trait Implementations

impl<T> Clone for ArcSupplier<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for ArcSupplier<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Display for ArcSupplier<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Supplier<T> for ArcSupplier<T>

fn get(&self) -> T

Generates and returns a value.

fn into_box(self) -> BoxSupplier<T>

where Self: 'static,

Converts to BoxSupplier.

fn into_rc(self) -> RcSupplier<T>

where Self: 'static,

Converts to RcSupplier.

fn into_arc(self) -> ArcSupplier<T>

Converts to ArcSupplier.

fn into_fn(self) -> impl Fn() -> T

Converts to a closure implementing Fn() -> T.

fn into_once(self) -> BoxSupplierOnce<T>

where Self: 'static,

Converts to BoxSupplierOnce.

fn to_box(&self) -> BoxSupplier<T>

where Self: 'static,

Converts to BoxSupplier by cloning.

fn to_rc(&self) -> RcSupplier<T>

where Self: 'static,

Converts to RcSupplier by cloning.

fn to_arc(&self) -> ArcSupplier<T>

Converts to ArcSupplier by cloning.

fn to_fn(&self) -> impl Fn() -> T

Converts to a closure by cloning.

fn to_once(&self) -> BoxSupplierOnce<T>

where Self: 'static,

Converts to BoxSupplierOnce without consuming self