memory_xor.rs

memory_xor.rs

// Only using standard library features for this illustrative concept,
// as the listed crates don't provide a direct, safe XOR-list implementation.

use std::ptr;
use std::mem;

// --- A simplified structure for an XOR-linked list node ---
struct Node {
    pub value: u32,
    // The "link" is the XOR of the *pointers* to the previous and next nodes.
    // In a real implementation, this would involve unsafe pointer casting.
    pub link: usize, 
}

// --- Illustration of the core XOR-linking logic ---

fn main() {
    println!("📦 XOR-Linked Memory Concept Demonstration 📦");

    // 1. Setup - Create three nodes
    // In a real scenario, these would be heap-allocated Boxed nodes.
    let mut node_a = Node { value: 10, link: 0 };
    let mut node_b = Node { value: 20, link: 0 };
    let mut node_c = Node { value: 30, link: 0 };

    // Get the memory addresses (pointers) as usize values
    // WARNING: This is *highly* unsafe and non-portable in a real application!
    // It's for demonstration only.
    let ptr_a = &node_a as *const Node as usize;
    let ptr_b = &mut node_b as *mut Node as usize; // Needs mut for link update
    let ptr_c = &node_c as *const Node as usize;

    println!("\nAddresses:");
    println!("Node A Address: {:#x}", ptr_a);
    println!("Node B Address: {:#x}", ptr_b);
    println!("Node C Address: {:#x}", ptr_c);
    
    // 2. Linking
    
    // --- Link A -> B ---
    // A's link = (0) XOR (Pointer to B)
    node_a.link = 0 ^ ptr_b;

    // --- Link B ---
    // B's link = (Pointer to A) XOR (Pointer to C)
    // We need 'mut' to modify B's link:
    let node_b_mut = unsafe { &mut *(ptr_b as *mut Node) };
    node_b_mut.link = ptr_a ^ ptr_c;

    // --- Link C <- B ---
    // C's link = (Pointer to B) XOR (0)
    node_c.link = ptr_b ^ 0;

    println!("\nLinks (XOR Pointers):");
    println!("Node A Link (0 ^ B): {:#x}", node_a.link);
    println!("Node B Link (A ^ C): {:#x}", node_b_mut.link);
    println!("Node C Link (B ^ 0): {:#x}", node_c.link);

    // 3. Traversal (Forward: A -> B -> C)

    println!("\nTraversal (A -> B -> C):");
    let mut current_ptr = ptr_a;
    let mut prev_ptr = 0; // Previous is NULL (0) for the start node

    while current_ptr != 0 {
        let current_node = unsafe { &*(current_ptr as *const Node) };
        println!("  - Value: {}", current_node.value);

        // Calculate the next pointer: Next = Link XOR Previous
        let next_ptr = current_node.link ^ prev_ptr;

        // Move to the next node
        prev_ptr = current_ptr;
        current_ptr = next_ptr;

        // Safety break for cycles, though none expected here
        if current_ptr == ptr_a && prev_ptr != 0 { break; } 
    }
}

https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=ab516638005b619a940a3f600449e9db