Auto merge of #52 - nox:boxed-slice, r=SimonSapin

Implement HeapSizeOf for boxed slices

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Author: bors-servo

src/lib.rs

@@ -88,7 +88,7 @@ pub trait HeapSizeOf {
 //
 // However, in the best case, the two approaches should give the same results.
 //
-impl<T: HeapSizeOf> HeapSizeOf for Box<T> {
+impl<T: HeapSizeOf + ?Sized> HeapSizeOf for Box<T> {
     fn heap_size_of_children(&self) -> usize {
         // Measure size of `self`.
         unsafe {
@@ -97,6 +97,12 @@ impl<T: HeapSizeOf> HeapSizeOf for Box<T> {
     }
 }
 
+impl<T: HeapSizeOf> HeapSizeOf for [T] {
+    fn heap_size_of_children(&self) -> usize {
+        self.iter().fold(0, |size, item| size + item.heap_size_of_children())
+    }
+}
+
 impl HeapSizeOf for String {
     fn heap_size_of_children(&self) -> usize {
         unsafe {
@@ -276,7 +282,7 @@ macro_rules! known_heap_size(
     );
 );
 
-known_heap_size!(0, char);
+known_heap_size!(0, char, str);
 known_heap_size!(0, u8, u16, u32, u64, usize);
 known_heap_size!(0, i8, i16, i32, i64, isize);
 known_heap_size!(0, bool, f32, f64);

tests/tests.rs

@@ -15,7 +15,7 @@ pub const EMPTY: *mut () = 0x1 as *mut ();
 mod unstable {
     extern crate alloc;
 
-    use heapsize::heap_size_of;
+    use heapsize::{HeapSizeOf, heap_size_of};
     use std::os::raw::c_void;
 
     #[repr(C, simd)]
@@ -91,6 +91,12 @@ mod unstable {
         let x = Box::new(OverAligned(0, 0, 0, 0));
         assert_eq!(unsafe { heap_size_of(&*x as *const _ as *const c_void) }, 32 + 32);
     }
+
+    #[test]
+    fn test_boxed_str() {
+        let x = "raclette".to_owned().into_boxed_str();
+        assert_eq!(x.heap_size_of_children(), 8);
+    }
 }
 
 #[test]
@@ -157,3 +163,9 @@ fn test_heap_size() {
     let x = vec![0i64, 1i64, 2i64, 3i64];
     assert_eq!(x.heap_size_of_children(), 32);
 }
+
+#[test]
+fn test_boxed_slice() {
+    let x = vec![1i64, 2i64].into_boxed_slice();
+    assert_eq!(x.heap_size_of_children(), 16)
+}