Implement Mul<usize> and MulAssign<usize> for String

src/libcollections/string.rs

@@ -60,7 +60,7 @@ use core::fmt;
 use core::hash;
 use core::iter::{FromIterator, FusedIterator};
 use core::mem;
-use core::ops::{self, Add, AddAssign, Index, IndexMut};
+use core::ops::{self, Add, AddAssign, Index, IndexMut, Mul, MulAssign};
 use core::ptr;
 use core::str as core_str;
 use core::str::pattern::Pattern;
@@ -1710,6 +1710,48 @@ impl<'a> AddAssign<&'a str> for String {
     }
 }
 
+/// Implements the `*` operator for multiplying `String` content.
+///
+/// ```
+/// let one = String::from("one");
+/// assert_eq!(one * 3, "oneoneone");
+/// ```
+#[stable(feature = "stringmultiply", since = "1.18.0")]
+impl Mul<usize> for String {
+    type Output = String;
+
+    #[inline]
+    fn mul(self, rhs: usize) -> String {
+        let size = self.len() * rhs;
+        let mut out = String::with_capacity(size);
+        for _ in 0..rhs {
+            out.push_str(self.as_str());
+        }
+        out
+    }
+}
+
+/// Implements the `*=` operator for multiplyng `String` content.
+///
+/// ```
+/// let mut one = String::from("one");
+/// one *= 3;
+/// assert_eq!(one, "oneoneone");
+/// ```
+#[stable(feature = "stringmultiply", since = "1.18.0")]
+impl MulAssign<usize> for String {
+    #[inline]
+    fn mul_assign(&mut self, rhs: usize) {
+        let content = self.clone();
+        let size = content.len() * rhs;
+        self.clear();
+        self.reserve(size);
+        for _ in 0..rhs {
+            self.push_str(content.as_str());
+        }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ops::Index<ops::Range<usize>> for String {
     type Output = str;

src/libcollections/tests/string.rs

@@ -206,6 +206,24 @@ fn test_add_assign() {
     assert_eq!(s.as_str(), "abcประเทศไทย中华Việt Nam");
 }
 
+#[test]
+fn test_mul() {
+    let s = String::from("abcประเทศไทย中华Việt Nam") * 0;
+    assert_eq!(s, "");
+    let s = String::from("abcประเทศไทย中华Việt Nam") * 2;
+    assert_eq!(s, "abcประเทศไทย中华Việt Namabcประเทศไทย中华Việt Nam");
+}
+
+#[test]
+fn test_mul_assign() {
+    let mut s = String::from("abcประเทศไทย中华Việt Nam");
+    s *= 0;
+    assert_eq!(s, "");
+    s = String::from("abcประเทศไทย中华Việt Nam");
+    s *= 2;
+    assert_eq!(s, "abcประเทศไทย中华Việt Namabcประเทศไทย中华Việt Nam");
+}
+
 #[test]
 fn test_push() {
     let mut data = String::from("ประเทศไทย中");