From 5858e3d5c7033f09b7fb2c006a2e227d0cff3d89 Mon Sep 17 00:00:00 2001
From: Jordan Gong <jordan.gong@protonmail.com>
Date: Sun, 20 Sep 2020 18:48:59 +0800
Subject: Count references `Rc`

---
 smart_pointer/src/main.rs | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

(limited to 'smart_pointer/src/main.rs')

diff --git a/smart_pointer/src/main.rs b/smart_pointer/src/main.rs
index d0be410..6778671 100644
--- a/smart_pointer/src/main.rs
+++ b/smart_pointer/src/main.rs
@@ -1,6 +1,7 @@
 // Recursive type using boxes
+use std::rc::Rc;
 enum List {
-    Cons(i32, Box<List>),
+    Cons(i32, Rc<List>),
     Nil,
 }
 
@@ -38,7 +39,7 @@ fn main() {
     println!("b = {}", b);
 
     use crate::List::{Cons, Nil};
-    let list = Cons(1, Box::new(Cons(2, Box::new(Cons(3, Box::new(Nil))))));
+    let list = Cons(1, Rc::new(Cons(2, Rc::new(Cons(3, Rc::new(Nil))))));
 
     // Dereferencing
     let x = 5;
@@ -79,4 +80,14 @@ fn main() {
     println!("CustomSmartPointer created.");
     drop(c);
     println!("CustomSmartPointer dropped before the end of main.");
+
+    let a = Rc::new(Cons(5, Rc::new(Cons(10, Rc::new(Nil)))));
+    println!("count after creating a = {}", Rc::strong_count(&a));
+    let b = Cons(3, Rc::clone(&a));
+    println!("count after creating b = {}", Rc::strong_count(&a));
+    {
+        let c = Cons(4, Rc::clone(&a));
+        println!("count after creating c = {}", Rc::strong_count(&a));
+    }
+    println!("count after c goes out of scope = {}", Rc::strong_count(&a));
 }
-- 
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