From 823321ee27f221db98b0e06a22601f126797eed0 Mon Sep 17 00:00:00 2001
From: gbrochar <gaetanbrochard@protonmail.com>
Date: Mon, 7 Dec 2020 12:44:23 +0100
Subject: [PATCH] smart pointers

---
 refcells/Cargo.toml        |  9 ++++
 refcells/src/main.rs       | 18 ++++++++
 smart_pointers/Cargo.toml  |  9 ++++
 smart_pointers/src/main.rs | 91 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 127 insertions(+)
 create mode 100644 refcells/Cargo.toml
 create mode 100644 refcells/src/main.rs
 create mode 100644 smart_pointers/Cargo.toml
 create mode 100644 smart_pointers/src/main.rs

diff --git a/refcells/Cargo.toml b/refcells/Cargo.toml
new file mode 100644
index 0000000..a0411eb
--- /dev/null
+++ b/refcells/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "refcells"
+version = "0.1.0"
+authors = ["gbrochar <gaetanbrochard@protonmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/refcells/src/main.rs b/refcells/src/main.rs
new file mode 100644
index 0000000..8834f24
--- /dev/null
+++ b/refcells/src/main.rs
@@ -0,0 +1,18 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+fn main() {
+    let mut x = 5;
+    let y = &mut x;
+
+    *y = 10;
+    println!("y: {}", y);
+    drop(y);
+    println!("x: {}", x);
+    
+    let a = Rc::new(RefCell::new(5));
+    let b = Rc::clone(&a);
+
+    *b.borrow_mut() += 10;
+    println!("a: {:?}, b: {:?}", a, b);
+}
diff --git a/smart_pointers/Cargo.toml b/smart_pointers/Cargo.toml
new file mode 100644
index 0000000..8f7d6bc
--- /dev/null
+++ b/smart_pointers/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "smart_pointers"
+version = "0.1.0"
+authors = ["gbrochar <gaetanbrochard@protonmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/smart_pointers/src/main.rs b/smart_pointers/src/main.rs
new file mode 100644
index 0000000..d6b228b
--- /dev/null
+++ b/smart_pointers/src/main.rs
@@ -0,0 +1,91 @@
+use std::rc::Rc;
+
+#[derive(Debug)]
+enum List {
+    Cons(i32, Rc<List>),
+    Nil,
+}
+
+use std::ops::Deref;
+
+struct MyBox<T>(T);
+
+impl<T> MyBox<T> {
+    fn new(x: T) -> MyBox<T> {
+        MyBox(x)
+    }
+}
+
+impl<T> Deref for MyBox<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.0
+    }
+}
+
+struct CustomSmartPointer {
+    data: String,
+}
+
+impl Drop for CustomSmartPointer {
+    fn drop(&mut self) {
+        println!("Dropping CustomSmartPointer with data `{}`!", self.data);
+    }
+}
+
+use crate::List::{Cons, Nil};
+
+fn hello(name: &str) {
+    println!("Hello, {}!", name);
+}
+
+fn main() {
+    let b = Box::new(5);
+    println!("b = {}", b);
+
+    let list = Cons(1, Rc::new(Cons(2, Rc::new(Cons(3, Rc::new(Nil))))));
+
+    println!("{:?}", list);
+
+    let x = 5;
+    let y = MyBox::new(x);
+    
+    assert_eq!(5, x);
+    assert_eq!(5, *y);
+
+    let m = MyBox::new(String::from("Rust"));
+    hello(&m);
+    hello(&(*m)[..]);
+
+    
+    let c = CustomSmartPointer {
+        data: String::from("my stuff"),
+    };
+    let d = CustomSmartPointer {
+        data: String::from("other stuff"),
+    };
+    println!("CustomSmartPointers created.");
+    println!("{}, {}", c.data, d.data);
+    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));
+    }
+    match b {
+        Cons(_aa, bb) => {
+            match &*bb {
+                Cons(cc, _dd) => println!("{}", cc),
+                Nil => println!("Nil"),
+            }
+        }
+        Nil => println!("Nil"),
+    };
+    println!("count after c goes out of scope = {}", Rc::strong_count(&a));
+}
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