code for 0x0c Operarot overloading

mike-kfed · mike-kfed · commit 0dc3179d8514 · 2021-07-02T17:31:40.000+02:00
diff --git a/0c_operator_overloading/rust/operator_overloading.rs b/0c_operator_overloading/rust/operator_overloading.rs
@@ -0,0 +1,62 @@
+use std::fmt;
+use std::fmt::Write;
+use std::ops;
+
+#[derive(Debug, Clone)]
+struct MyString(String);
+
+impl fmt::Display for MyString {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl ops::Add<String> for MyString {
+    type Output = MyString;
+
+    fn add(self, rhs: String) -> Self::Output {
+        println!("> MyString.add({}) was called", &rhs);
+        MyString(format!("{}{}", self.0, rhs))
+    }
+}
+
+impl ops::Add<i32> for MyString {
+    type Output = MyString;
+
+    fn add(self, rhs: i32) -> Self::Output {
+        println!("> MyString.add({}) was called", &rhs);
+        MyString(format!("{}{}", self.0, rhs))
+    }
+}
+
+impl ops::Add<MyString> for i32 {
+    type Output = MyString;
+
+    fn add(self, rhs: MyString) -> Self::Output {
+        println!("> i32.add({}) was called", &rhs);
+        MyString(format!("{}{}", self, rhs))
+    }
+}
+
+impl ops::Mul<i32> for MyString {
+    type Output = MyString;
+
+    fn mul(self, rhs: i32) -> Self::Output {
+        println!("> MyString.mul({}) was called", &rhs);
+        let caplen: usize = if rhs <= 0 { 0 } else { rhs as usize };
+        let mut temp = String::with_capacity(&self.0.len() * caplen);
+        for _ in 0..rhs {
+            temp.write_str(&self.0).expect("writing to string failed");
+        }
+        MyString(temp)
+    }
+}
+
+fn main() {
+    let ms = MyString("Foo".to_string());
+    println!("Foo + Bar = {}", ms + "Bar".to_string());
+    println!("Foo + -12 = {}", ms + -12_i32);
+    println!("100 + Foo = {}", 100_i32 + ms.clone());
+    println!("Foo * -12 = {}", ms.clone() * -12_i32);
+    println!("Foo * 12 = {}", ms.clone() * 12_i32);
+}
