子struct内保存parent引用

[wuyuedefeng]

1. A raw ptr version:

child

struct Parent {
    name: String,
    child: Child,
}

struct Child {
    name: String,
    parent: *const Parent,
}

fn main() {
    let child = Child {
        name: "child".into(),
        parent: std::ptr::null(),
    };
    let mut parent = Parent { 
        name: "parent".into(),
        child,
    };
    parent.child.parent = &parent;
    println!("parent: {}", parent.name);
    println!("child: {}", parent.child.name);
}

children

struct Parent {
    name: String,
    children: Vec<Child>,
}

struct Child {
    name: String,
    parent: *const Parent,
}

fn main() {
    let mut parent = Parent { name: "parent".into(), children: Vec::new() };
    let child1 = Child { name: "child1".into(), parent: &parent };
    parent.children.push(child1);
    
    for child in parent.children.iter() {
        if !child.parent.is_null() {
            unsafe {
                println!("child: {}, parent: {}", child.name, (*(child.parent)).name);    
            }
        }
    }
}

Child loop nesting

struct Node {
    name: String,
    parent: *const Node,
    children: Vec<Node>,
}

fn main() {
    let mut parent = Node { name: "parent".into(), parent: std::ptr::null(), children: Vec::new() };
    let child1 = Node { name: "child1".into(), parent: &parent, children: Vec::new() };
    parent.children.push(child1);
    
    for child in parent.children.iter() {
        if !child.parent.is_null() {
            unsafe {
                println!("child: {}, parent: {}", child.name, (*(child.parent)).name);    
            }
        }
    }
}

2. A Rc version:

use std::rc::Rc;

// All Parent state that needs to be shared with Child goes here
struct Data {
    name: String
}

struct Parent {
    children: Vec<Child>,
    data: Rc<Data>,
}

struct Child {
    parent: Rc<Data>, // or Weak<Inner> if that's desirable
    data: Rc<Data>,
}

fn main() {
    let data = Rc::new(Data { name: "parent".into() });
    let mut parent = Parent {children: Vec::new(), data};
    let child = Child {parent: Rc::clone(&parent.data), data: Rc::new(Data { name: "child1".into() })};
    parent.children.push(child);
    
    for child in parent.children.iter() {
        println!("child: {}, parent: {}", child.data.name, child.parent.name);
    }
}