Struct RcTransformer 

pub struct RcTransformer<T, R> { /* private fields */ }

RcTransformer - single-threaded transformer wrapper

A single-threaded, clonable transformer wrapper optimized for scenarios that require sharing without thread-safety overhead.

Features

• Based on: Rc<dyn Fn(T) -> R>
• Ownership: Shared ownership via reference counting (non-atomic)
• Reusability: Can be called multiple times (each call consumes its input)
• Thread Safety: Not thread-safe (no Send + Sync)
• Clonable: Cheap cloning via Rc::clone

Author

Hu Haixing

Implementations

impl<T, R> RcTransformer<T, R>

where T: 'static, R: 'static,

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

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

Creates a new RcTransformer

Parameters

• f - The closure or function to wrap

Examples

use prism3_function::{RcTransformer, Transformer};

let double = RcTransformer::new(|x: i32| x * 2);
assert_eq!(double.transform(21), 42);

Examples found in repository

examples/transformer_demo.rs (line 57)

fn main() {
    println!("=== Transformer Demo - Type Transformation (consumes T) ===\n");

    // ====================================================================
    // Part 1: BoxTransformer - Single ownership, reusable
    // ====================================================================
    println!("--- BoxTransformer ---");
    let double = BoxTransformer::new(|x: i32| x * 2);
    println!("double.transform(21) = {}", double.transform(21));
    println!("double.transform(42) = {}", double.transform(42));

    // Identity and constant
    let identity = BoxTransformer::<i32, i32>::identity();
    println!("identity.transform(42) = {}", identity.transform(42));

    let constant = BoxTransformer::constant("hello");
    println!("constant.transform(123) = {}", constant.transform(123));
    println!();

    // ====================================================================
    // Part 2: ArcTransformer - Thread-safe, cloneable
    // ====================================================================
    println!("--- ArcTransformer ---");
    let arc_double = ArcTransformer::new(|x: i32| x * 2);
    let arc_cloned = arc_double.clone();

    println!("arc_double.transform(21) = {}", arc_double.transform(21));
    println!("arc_cloned.transform(42) = {}", arc_cloned.transform(42));

    // Multi-threaded usage
    let for_thread = arc_double.clone();
    let handle = thread::spawn(move || for_thread.transform(100));
    println!(
        "In main thread: arc_double.transform(50) = {}",
        arc_double.transform(50)
    );
    println!("In child thread: result = {}", handle.join().unwrap());
    println!();

    // ====================================================================
    // Part 3: RcTransformer - Single-threaded, cloneable
    // ====================================================================
    println!("--- RcTransformer ---");
    let rc_double = RcTransformer::new(|x: i32| x * 2);
    let rc_cloned = rc_double.clone();

    println!("rc_double.transform(21) = {}", rc_double.transform(21));
    println!("rc_cloned.transform(42) = {}", rc_cloned.transform(42));
    println!();

    // ====================================================================
    // Part 4: Practical Examples
    // ====================================================================
    println!("=== Practical Examples ===\n");

    // Example 1: String transformation
    println!("--- String Transformation ---");
    let to_upper = BoxTransformer::new(|s: String| s.to_uppercase());
    println!(
        "to_upper.transform('hello') = {}",
        to_upper.transform("hello".to_string())
    );
    println!(
        "to_upper.transform('world') = {}",
        to_upper.transform("world".to_string())
    );
    println!();

    // Example 2: Type conversion pipeline
    println!("--- Type Conversion Pipeline ---");
    let parse_int = BoxTransformer::new(|s: String| s.parse::<i32>().unwrap_or(0));
    let double_int = BoxTransformer::new(|x: i32| x * 2);
    let to_string = BoxTransformer::new(|x: i32| x.to_string());

    let pipeline = parse_int.and_then(double_int).and_then(to_string);
    println!(
        "pipeline.transform('21') = {}",
        pipeline.transform("21".to_string())
    );
    println!();

    // Example 3: Shared transformation logic
    println!("--- Shared Transformation Logic ---");
    let square = ArcTransformer::new(|x: i32| x * x);

    // Can be shared across different parts of the program
    let transformer1 = square.clone();
    let transformer2 = square.clone();

    println!("transformer1.transform(5) = {}", transformer1.transform(5));
    println!("transformer2.transform(7) = {}", transformer2.transform(7));
    println!("square.transform(3) = {}", square.transform(3));
    println!();

    // Example 4: Transformer registry
    println!("--- Transformer Registry ---");
    let mut transformers: HashMap<String, RcTransformer<i32, String>> = HashMap::new();

    transformers.insert(
        "double".to_string(),
        RcTransformer::new(|x: i32| format!("Doubled: {}", x * 2)),
    );
    transformers.insert(
        "square".to_string(),
        RcTransformer::new(|x: i32| format!("Squared: {}", x * x)),
    );

    if let Some(transformer) = transformers.get("double") {
        println!("Transformer 'double': {}", transformer.transform(7));
    }
    if let Some(transformer) = transformers.get("square") {
        println!("Transformer 'square': {}", transformer.transform(7));
    }
    println!();

    // ====================================================================
    // Part 5: Trait Usage
    // ====================================================================
    println!("=== Trait Usage ===\n");

    fn apply_transformer<F: Transformer<i32, String>>(f: &F, x: i32) -> String {
        f.transform(x)
    }

    let to_string = BoxTransformer::new(|x: i32| format!("Value: {}", x));
    println!("Via trait: {}", apply_transformer(&to_string, 42));

    println!("\n=== Demo Complete ===");
}

pub fn identity() -> RcTransformer<T, T>

Creates an identity transformer

Examples

use prism3_function::{RcTransformer, Transformer};

let identity = RcTransformer::<i32, i32>::identity();
assert_eq!(identity.transform(42), 42);

pub fn and_then<S, F>(&self, after: F) -> RcTransformer<T, S>

where S: 'static, F: Transformer<R, S> + 'static,

Chain composition - applies self first, then after

Creates a new transformer that applies this transformer first, then applies the after transformer to the result. Uses &self, so original transformer remains usable.

Type Parameters

• S - The output type of the after transformer
• F - The type of the after transformer (must implement Transformer<R, S>)

Parameters

• after - The transformer to apply after self. Note: This parameter is passed by value and will transfer ownership. If you need to preserve the original transformer, clone it first (if it implements Clone). Can be:
  • A closure: |x: R| -> S
  • A function pointer: fn(R) -> S
  • A BoxTransformer<R, S>
  • An RcTransformer<R, S> (will be moved)
  • An ArcTransformer<R, S>
  • Any type implementing Transformer<R, S>

Returns

A new RcTransformer representing the composition

Examples

Direct value passing (ownership transfer)

use prism3_function::{RcTransformer, Transformer};

let double = RcTransformer::new(|x: i32| x * 2);
let to_string = RcTransformer::new(|x: i32| x.to_string());

// to_string is moved here
let composed = double.and_then(to_string);

// Original double transformer still usable (uses &self)
assert_eq!(double.transform(21), 42);
assert_eq!(composed.transform(21), "42");
// to_string.transform(5); // Would not compile - moved

Preserving original with clone

use prism3_function::{RcTransformer, Transformer};

let double = RcTransformer::new(|x: i32| x * 2);
let to_string = RcTransformer::new(|x: i32| x.to_string());

// Clone to preserve original
let composed = double.and_then(to_string.clone());
assert_eq!(composed.transform(21), "42");

// Both originals still usable
assert_eq!(double.transform(21), 42);
assert_eq!(to_string.transform(5), "5");

pub fn compose<S, F>(&self, before: F) -> RcTransformer<S, R>

where S: 'static, F: Transformer<S, T> + 'static,

Reverse composition - applies before first, then self

Creates a new transformer that applies the before transformer first, then applies this transformer to the result. Uses &self, so original transformer remains usable.

Type Parameters

• S - The input type of the before transformer
• F - The type of the before transformer (must implement Transformer<S, T>)

Parameters

• before - The transformer to apply before self. Note: This parameter is passed by value and will transfer ownership. If you need to preserve the original transformer, clone it first (if it implements Clone). Can be:
  • A closure: |x: S| -> T
  • A function pointer: fn(S) -> T
  • A BoxTransformer<S, T>
  • An RcTransformer<S, T> (will be moved)
  • An ArcTransformer<S, T>
  • Any type implementing Transformer<S, T>

Returns

A new RcTransformer representing the composition

Examples

Direct value passing (ownership transfer)

use prism3_function::{RcTransformer, Transformer};

let double = RcTransformer::new(|x: i32| x * 2);
let add_one = RcTransformer::new(|x: i32| x + 1);

// add_one is moved here
let composed = double.compose(add_one);
assert_eq!(composed.transform(5), 12); // (5 + 1) * 2
// add_one.transform(3); // Would not compile - moved

Preserving original with clone

use prism3_function::{RcTransformer, Transformer};

let double = RcTransformer::new(|x: i32| x * 2);
let add_one = RcTransformer::new(|x: i32| x + 1);

// Clone to preserve original
let composed = double.compose(add_one.clone());
assert_eq!(composed.transform(5), 12); // (5 + 1) * 2

// Both originals still usable
assert_eq!(double.transform(10), 20);
assert_eq!(add_one.transform(3), 4);

pub fn when<P>(self, predicate: P) -> RcConditionalTransformer<T, R>

where P: Predicate<T> + 'static,

Creates a conditional transformer (single-threaded shared version)

Returns a transformer that only executes when a predicate is satisfied. You must call or_else() to provide an alternative transformer.

Parameters

• predicate - The condition to check. Note: This parameter is passed by value and will transfer ownership. If you need to preserve the original predicate, clone it first (if it implements Clone). Can be:
  • A closure: |x: &T| -> bool
  • A function pointer: fn(&T) -> bool
  • A BoxPredicate<T>
  • An RcPredicate<T>
  • An ArcPredicate<T>
  • Any type implementing Predicate<T>

Returns

Returns RcConditionalTransformer<T, R>

Examples

Basic usage with or_else

use prism3_function::{Transformer, RcTransformer};

let double = RcTransformer::new(|x: i32| x * 2);
let identity = RcTransformer::<i32, i32>::identity();
let conditional = double.when(|x: &i32| *x > 0).or_else(identity);

let conditional_clone = conditional.clone();

assert_eq!(conditional.transform(5), 10);
assert_eq!(conditional_clone.transform(-5), -5);

Preserving predicate with clone

use prism3_function::{Transformer, RcTransformer, RcPredicate};

let double = RcTransformer::new(|x: i32| x * 2);
let is_positive = RcPredicate::new(|x: &i32| *x > 0);

// Clone to preserve original predicate
let conditional = double.when(is_positive.clone())
    .or_else(RcTransformer::identity());

assert_eq!(conditional.transform(5), 10);

// Original predicate still usable
assert!(is_positive.test(&3));

impl<T, R> RcTransformer<T, R>

where T: 'static, R: Clone + 'static,

pub fn constant(value: R) -> RcTransformer<T, R>

Creates a constant transformer

Examples

use prism3_function::{RcTransformer, Transformer};

let constant = RcTransformer::constant("hello");
assert_eq!(constant.transform(123), "hello");

Trait Implementations

impl<T, R> Clone for RcTransformer<T, R>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T, R> Transformer<T, R> for RcTransformer<T, R>

fn transform(&self, input: T) -> R

Transforms the input value to produce an output value

fn into_box(self) -> BoxTransformer<T, R>

where T: 'static, R: 'static,

Converts to BoxTransformer

fn into_rc(self) -> RcTransformer<T, R>

where T: 'static, R: 'static,

Converts to RcTransformer

fn into_arc(self) -> ArcTransformer<T, R>

where Self: Send + Sync, T: Send + Sync + 'static, R: Send + Sync + 'static,

Converts to ArcTransformer

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

where T: 'static, R: 'static,

Converts transformer to a closure