Struct BoxConditionalMutator 

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

BoxConditionalMutator struct

A conditional mutator that only executes when a predicate is satisfied. Uses BoxMutator and BoxPredicate for single ownership semantics.

This type is typically created by calling BoxMutator::when() and is designed to work with the or_else() method to create if-then-else logic.

Features

• Single Ownership: Not cloneable, consumes self on use
• Conditional Execution: Only mutates when predicate returns true
• Chainable: Can add or_else branch to create if-then-else logic
• Implements Mutator: Can be used anywhere a Mutator is expected

Examples

Basic Conditional Execution

use prism3_function::{Mutator, BoxMutator};

let mutator = BoxMutator::new(|x: &mut i32| *x *= 2);
let mut conditional = mutator.when(|x: &i32| *x > 0);

let mut positive = 5;
conditional.mutate(&mut positive);
assert_eq!(positive, 10); // Executed

let mut negative = -5;
conditional.mutate(&mut negative);
assert_eq!(negative, -5); // Not executed

With or_else Branch

use prism3_function::{Mutator, BoxMutator};

let mut mutator = BoxMutator::new(|x: &mut i32| *x *= 2)
    .when(|x: &i32| *x > 0)
    .or_else(|x: &mut i32| *x -= 1);

let mut positive = 5;
mutator.mutate(&mut positive);
assert_eq!(positive, 10); // when branch executed

let mut negative = -5;
mutator.mutate(&mut negative);
assert_eq!(negative, -6); // or_else branch executed

Author

Haixing Hu

Implementations

impl<T> BoxConditionalMutator<T>

where T: 'static,

pub fn and_then<C>(self, next: C) -> BoxMutator<T>

where C: Mutator<T> + 'static,

Chains another mutator in sequence

Combines the current conditional mutator with another mutator into a new mutator. The current conditional mutator executes first, followed by the next mutator.

Parameters

• next - The next mutator to execute. Note: This parameter is passed by value and will transfer ownership. If you need to preserve the original mutator, clone it first (if it implements Clone). Can be:
  • A closure: |x: &mut T|
  • A BoxMutator<T>
  • An ArcMutator<T>
  • An RcMutator<T>
  • Any type implementing Mutator<T>

Returns

Returns a new BoxMutator<T>

Examples

Direct value passing (ownership transfer)

use prism3_function::{Mutator, BoxMutator};

let cond1 = BoxMutator::new(|x: &mut i32| *x *= 2).when(|x: &i32| *x > 0);
let cond2 = BoxMutator::new(|x: &mut i32| *x = 100).when(|x: &i32| *x > 100);

// cond2 is moved here
let mut chained = cond1.and_then(cond2);
let mut value = 60;
chained.mutate(&mut value);
assert_eq!(value, 100); // First *2 = 120, then capped to 100
// cond2.mutate(&mut value); // Would not compile - moved

Preserving original with clone

use prism3_function::{Mutator, BoxMutator};

let cond1 = BoxMutator::new(|x: &mut i32| *x *= 2).when(|x: &i32| *x > 0);
let cond2 = BoxMutator::new(|x: &mut i32| *x = 100).when(|x: &i32| *x > 100);

// Clone to preserve original
let mut chained = cond1.and_then(cond2.clone());
let mut value = 60;
chained.mutate(&mut value);
assert_eq!(value, 100); // First *2 = 120, then capped to 100

// Original still usable
let mut value2 = 50;
cond2.mutate(&mut value2);
assert_eq!(value2, 100);

pub fn or_else<C>(self, else_mutator: C) -> BoxMutator<T>

where C: Mutator<T> + 'static,

Adds an else branch

Executes the original mutator when the condition is satisfied, otherwise executes else_mutator.

Parameters

• else_mutator - The mutator for the else branch. Note: This parameter is passed by value and will transfer ownership. If you need to preserve the original mutator, clone it first (if it implements Clone). Can be:
  • A closure: |x: &mut T|
  • A BoxMutator<T>
  • An RcMutator<T>
  • An ArcMutator<T>
  • Any type implementing Mutator<T>

Returns

Returns the composed BoxMutator<T>

Examples

Using a closure (recommended)

use prism3_function::{Mutator, BoxMutator};

let mut mutator = BoxMutator::new(|x: &mut i32| *x *= 2)
    .when(|x: &i32| *x > 0)
    .or_else(|x: &mut i32| *x -= 1);

let mut positive = 5;
mutator.mutate(&mut positive);
assert_eq!(positive, 10); // Condition satisfied, execute *2

let mut negative = -5;
mutator.mutate(&mut negative);
assert_eq!(negative, -6); // Condition not satisfied, execute -1

Examples found in repository

examples/mutator_demo.rs (line 109)

fn main() {
    println!("=== Mutator Demo ===\n");

    // ========================================================================
    // Example 1: BoxMutator Basic Usage
    // ========================================================================
    println!("Example 1: BoxMutator Basic Usage");
    println!("{}", "-".repeat(50));

    let mut mutator = BoxMutator::new(|x: &mut i32| {
        *x *= 2;
    });
    let mut value = 5;
    println!("Initial value: {}", value);
    mutator.mutate(&mut value);
    println!("After BoxMutator execution: {}\n", value);

    // ========================================================================
    // Example 2: BoxMutator Method Chaining
    // ========================================================================
    println!("Example 2: BoxMutator Method Chaining");
    println!("{}", "-".repeat(50));

    let mut chained = BoxMutator::new(|x: &mut i32| {
        *x *= 2; // multiply by 2
    })
    .and_then(|x: &mut i32| {
        *x += 10; // add 10
    })
    .and_then(|x: &mut i32| {
        *x = *x * *x; // square
    });

    let mut value = 5;
    println!("Initial value: {}", value);
    chained.mutate(&mut value);
    println!("Result: {} (5 * 2 + 10 = 20, 20 * 20 = 400)\n", value);

    // ========================================================================
    // Example 3: Closure Extension Methods
    // ========================================================================
    println!("Example 3: Direct Use of Closure Extension Methods");
    println!("{}", "-".repeat(50));

    let mut closure_chain = (|x: &mut i32| *x *= 2).and_then(|x: &mut i32| *x += 10);

    let mut value = 5;
    println!("Initial value: {}", value);
    closure_chain.mutate(&mut value);
    println!("Result: {} (5 * 2 + 10 = 20)\n", value);

    // ========================================================================
    // Example 4: BoxMutator Factory Methods
    // ========================================================================
    println!("Example 4: BoxMutator Factory Methods");
    println!("{}", "-".repeat(50));

    // noop
    let mut noop = BoxMutator::<i32>::noop();
    let mut value = 42;
    println!("Before noop: {}", value);
    noop.mutate(&mut value);
    println!("After noop: {} (unchanged)\n", value);

    // ========================================================================
    // Example 5: Conditional Mutator
    // ========================================================================
    println!("Example 5: Conditional Mutator");
    println!("{}", "-".repeat(50));

    // when (conditional execution)
    let mut increment_if_positive = BoxMutator::new(|x: &mut i32| *x += 1).when(|x: &i32| *x > 0);

    let mut positive = 5;
    let mut negative = -5;
    println!(
        "Before when - positive: {}, negative: {}",
        positive, negative
    );
    increment_if_positive.mutate(&mut positive);
    increment_if_positive.mutate(&mut negative);
    println!(
        "After when - positive: {}, negative: {}\n",
        positive, negative
    );

    // when().or_else() (conditional branching)
    let mut adjust = BoxMutator::new(|x: &mut i32| *x *= 2)
        .when(|x: &i32| *x > 0)
        .or_else(|x: &mut i32| *x = -*x);

    let mut positive = 10;
    let mut negative = -10;
    println!(
        "Before when().or_else() - positive: {}, negative: {}",
        positive, negative
    );
    adjust.mutate(&mut positive);
    adjust.mutate(&mut negative);
    println!(
        "After when().or_else() - positive: {}, negative: {}\n",
        positive, negative
    );

    // ========================================================================
    // Example 6: ArcMutator - Multi-threaded Sharing
    // ========================================================================
    println!("Example 6: ArcMutator - Multi-threaded Sharing");
    println!("{}", "-".repeat(50));

    let shared = ArcMutator::new(|x: &mut i32| *x *= 2);

    // Clone for another thread
    let shared_clone = shared.clone();
    let handle = thread::spawn(move || {
        let mut value = 5;
        let mut mutator = shared_clone;
        mutator.mutate(&mut value);
        println!("In thread: 5 * 2 = {}", value);
        value
    });

    // Use in main thread
    let mut value = 3;
    let mut mutator = shared;
    mutator.mutate(&mut value);
    println!("Main thread: 3 * 2 = {}", value);

    let thread_result = handle.join().unwrap();
    println!("Thread result: {}\n", thread_result);

    // ========================================================================
    // Example 7: ArcMutator Composition (without consuming original mutator)
    // ========================================================================
    println!("Example 7: ArcMutator Composition (borrowing &self)");
    println!("{}", "-".repeat(50));

    let double = ArcMutator::new(|x: &mut i32| *x *= 2);
    let add_ten = ArcMutator::new(|x: &mut i32| *x += 10);

    // Composition doesn't consume the original mutator
    let pipeline1 = double.and_then(&add_ten);
    let pipeline2 = add_ten.and_then(&double);

    let mut value1 = 5;
    let mut p1 = pipeline1;
    p1.mutate(&mut value1);
    println!("pipeline1 (double then add): 5 -> {}", value1);

    let mut value2 = 5;
    let mut p2 = pipeline2;
    p2.mutate(&mut value2);
    println!("pipeline2 (add then double): 5 -> {}", value2);

    // double and add_ten are still available
    let mut value3 = 10;
    let mut d = double;
    d.mutate(&mut value3);
    println!("Original double still available: 10 -> {}\n", value3);

    // ========================================================================
    // Example 8: RcMutator - Single-threaded Sharing
    // ========================================================================
    println!("Example 8: RcMutator - Single-threaded Sharing");
    println!("{}", "-".repeat(50));

    let rc_mutator = RcMutator::new(|x: &mut i32| *x *= 2);

    // Clone multiple copies
    let clone1 = rc_mutator.clone();
    let clone2 = rc_mutator.clone();

    let mut value1 = 5;
    let mut c1 = clone1;
    c1.mutate(&mut value1);
    println!("clone1: 5 -> {}", value1);

    let mut value2 = 3;
    let mut c2 = clone2;
    c2.mutate(&mut value2);
    println!("clone2: 3 -> {}", value2);

    let mut value3 = 7;
    let mut c3 = rc_mutator;
    c3.mutate(&mut value3);
    println!("Original: 7 -> {}\n", value3);

    // ========================================================================
    // Example 9: RcMutator Composition (borrowing &self)
    // ========================================================================
    println!("Example 9: RcMutator Composition (borrowing &self)");
    println!("{}", "-".repeat(50));

    let double = RcMutator::new(|x: &mut i32| *x *= 2);
    let add_ten = RcMutator::new(|x: &mut i32| *x += 10);

    let pipeline1 = double.and_then(&add_ten);
    let pipeline2 = add_ten.and_then(&double);

    let mut value1 = 5;
    let mut p1 = pipeline1;
    p1.mutate(&mut value1);
    println!("pipeline1 (double then add): 5 -> {}", value1);

    let mut value2 = 5;
    let mut p2 = pipeline2;
    p2.mutate(&mut value2);
    println!("pipeline2 (add then double): 5 -> {}\n", value2);

    // ========================================================================
    // Example 10: Unified Mutator trait
    // ========================================================================
    println!("Example 10: Unified Mutator trait");
    println!("{}", "-".repeat(50));

    fn apply_to_all<M: Mutator<i32>>(mutator: &mut M, values: &mut [i32]) {
        for value in values.iter_mut() {
            mutator.mutate(value);
        }
    }

    let mut values1 = vec![1, 2, 3, 4, 5];
    let mut box_mut = BoxMutator::new(|x: &mut i32| *x *= 2);
    println!("Using BoxMutator: {:?}", values1);
    apply_to_all(&mut box_mut, &mut values1);
    println!("Result: {:?}", values1);

    let mut values2 = vec![1, 2, 3, 4, 5];
    let mut arc_mut = ArcMutator::new(|x: &mut i32| *x *= 2);
    println!("Using ArcMutator: {:?}", values2);
    apply_to_all(&mut arc_mut, &mut values2);
    println!("Result: {:?}", values2);

    let mut values3 = vec![1, 2, 3, 4, 5];
    let mut rc_mut = RcMutator::new(|x: &mut i32| *x *= 2);
    println!("Using RcMutator: {:?}", values3);
    apply_to_all(&mut rc_mut, &mut values3);
    println!("Result: {:?}", values3);

    let mut values4 = vec![1, 2, 3, 4, 5];
    let mut closure = |x: &mut i32| *x *= 2;
    println!("Using closure: {:?}", values4);
    apply_to_all(&mut closure, &mut values4);
    println!("Result: {:?}\n", values4);

    // ========================================================================
    // Example 11: Complex Data Processing Pipeline
    // ========================================================================
    println!("Example 11: Complex Data Processing Pipeline");
    println!("{}", "-".repeat(50));

    let mut pipeline = BoxMutator::new(|x: &mut i32| {
        // Validation: clamp to 0-100
        *x = (*x).clamp(0, 100);
    })
    .and_then(|x: &mut i32| {
        // Normalization: scale to 0-10
        *x /= 10;
    })
    .and_then(|x: &mut i32| {
        // Transformation: square
        *x = *x * *x;
    });

    let mut value1 = -50;
    pipeline.mutate(&mut value1);
    println!("-50 -> {}", value1);

    let mut value2 = 200;
    pipeline.mutate(&mut value2);
    println!("200 -> {}", value2);

    let mut value3 = 30;
    pipeline.mutate(&mut value3);
    println!("30 -> {}\n", value3);

    // ========================================================================
    // Example 12: String Processing
    // ========================================================================
    println!("Example 12: String Processing");
    println!("{}", "-".repeat(50));

    let mut string_processor = BoxMutator::new(|s: &mut String| s.retain(|c| !c.is_whitespace()))
        .and_then(|s: &mut String| *s = s.to_lowercase())
        .and_then(|s: &mut String| s.push_str("!!!"));

    let mut text = String::from("Hello World");
    println!("Original: {}", text);
    string_processor.mutate(&mut text);
    println!("After processing: {}\n", text);

    // ========================================================================
    // Example 13: Type Conversion
    // ========================================================================
    println!("Example 13: Type Conversion");
    println!("{}", "-".repeat(50));

    // Closure -> BoxMutator
    let closure = |x: &mut i32| *x *= 2;
    let mut box_mut = closure.into_box();
    let mut value = 5;
    box_mut.mutate(&mut value);
    println!("Closure -> BoxMutator: 5 -> {}", value);

    // Closure -> RcMutator
    let closure = |x: &mut i32| *x *= 2;
    let mut rc_mut = closure.into_rc();
    let mut value = 5;
    rc_mut.mutate(&mut value);
    println!("Closure -> RcMutator: 5 -> {}", value);

    // Closure -> ArcMutator
    let closure = |x: &mut i32| *x *= 2;
    let mut arc_mut = closure.into_arc();
    let mut value = 5;
    arc_mut.mutate(&mut value);
    println!("Closure -> ArcMutator: 5 -> {}", value);

    // BoxMutator -> RcMutator
    let box_mut = BoxMutator::new(|x: &mut i32| *x *= 2);
    let mut rc_mut = box_mut.into_rc();
    let mut value = 5;
    rc_mut.mutate(&mut value);
    println!("BoxMutator -> RcMutator: 5 -> {}", value);

    // RcMutator -> BoxMutator
    let rc_mut = RcMutator::new(|x: &mut i32| *x *= 2);
    let mut box_mut = rc_mut.into_box();
    let mut value = 5;
    box_mut.mutate(&mut value);
    println!("RcMutator -> BoxMutator: 5 -> {}\n", value);

    // ========================================================================
    // Example 14: Custom Types
    // ========================================================================
    println!("Example 14: Custom Types");
    println!("{}", "-".repeat(50));

    #[derive(Debug, Clone)]
    struct Point {
        x: i32,
        y: i32,
    }

    let mut processor = BoxMutator::new(|p: &mut Point| p.x *= 2)
        .and_then(|p: &mut Point| p.y *= 2)
        .and_then(|p: &mut Point| p.x += p.y);

    let mut point = Point { x: 3, y: 4 };
    println!("Original point: {:?}", point);
    processor.mutate(&mut point);
    println!("After processing: {:?}\n", point);

    println!("=== All Examples Completed ===");
}

Trait Implementations

impl<T> Mutator<T> for BoxConditionalMutator<T>

where T: 'static,

fn mutate(&mut self, value: &mut T)

Performs the mutation operation

fn into_box(self) -> BoxMutator<T>

Convert this mutator into a BoxMutator<T>.

fn into_rc(self) -> RcMutator<T>

Convert this mutator into an RcMutator<T>.

fn into_fn(self) -> impl FnMut(&mut T)

Consume the mutator and return an FnMut(&mut T) closure.

fn into_arc(self) -> ArcMutator<T>

where Self: Sized + Send + 'static, T: Send + 'static,

Convert this mutator into an ArcMutator<T>.