Merge pull request fizyk20#12 from llogiq/map

new map method

Author: fizyk20

Cargo.toml

@@ -12,7 +12,8 @@ documentation = "http://fizyk20.github.io/generic-array/generic_array/"
 name = "generic_array"
 
 [dependencies]
-typenum = "1.*"
+typenum = "1.3.1"
+nodrop = "0.1.6"
 
 [features]
 no_std = ["typenum/no_std"]

src/lib.rs

@@ -35,7 +35,9 @@
 #[cfg(feature="no_std")]
 extern crate core as std;
 extern crate typenum;
+extern crate nodrop;
 pub mod arr;
+use nodrop::NoDrop;
 use typenum::uint::{Unsigned, UTerm, UInt};
 use typenum::bit::{B0, B1};
 use std::fmt::Debug;
@@ -45,7 +47,7 @@ use std::ops::{Deref, DerefMut};
 use std::ptr;
 use std::slice;
 
-/// Trait making GenericArray work, marking types to be used as length of an array
+/// Trait making `GenericArray` work, marking types to be used as length of an array
 pub unsafe trait ArrayLength<T> : Unsigned {
     /// Associated type representing the array type for the number
     type ArrayType;
@@ -105,7 +107,7 @@ unsafe impl<T, N: ArrayLength<T>> ArrayLength<T> for UInt<N, B1> {
     type ArrayType = GenericArrayImplOdd<T, N::ArrayType>;
 }
 
-/// Struct representing a generic array - GenericArray<T, N> works like [T; N]
+/// Struct representing a generic array - `GenericArray<T, N>` works like [T; N]
 #[allow(dead_code)]
 pub struct GenericArray<T, U: ArrayLength<T>> {
     data: U::ArrayType
@@ -129,14 +131,45 @@ impl<T, N> DerefMut for GenericArray<T, N> where N: ArrayLength<T> {
     }
 }
 
+impl<T, N> GenericArray<T, N> where N: ArrayLength<T> {
+    /// map a function over a  slice to a `GenericArray`.
+    /// The length of the slice *must* be equal to the length of the array
+    pub fn map_slice<S, F: Fn(&S) -> T>(s: &[S], f: F) -> GenericArray<T, N> {
+        assert_eq!(s.len(), N::to_usize());
+        map_inner(s, f)
+    }
+    
+    /// map a function over a `GenericArray`.
+    pub fn map<U, F>(self, f: F) -> GenericArray<U, N>
+    where F: Fn(&T) -> U, N: ArrayLength<U> {
+        map_inner(&self, f)
+    }
+}
+
+#[inline]
+fn map_inner<S, F, T, N>(list: &[S], f: F) -> GenericArray<T, N>
+where F: Fn(&S) -> T, N: ArrayLength<T> {
+     unsafe {
+        let mut res : NoDrop<GenericArray<T, N>> = 
+                      NoDrop::new(std::mem::uninitialized());
+        for (s, r) in list.iter().zip(res.iter_mut()) {
+            std::ptr::write(r, f(s))
+        }
+        res.into_inner()
+    }
+}
+
 impl<T: Default, N> GenericArray<T, N> where N: ArrayLength<T> {
 
     /// Function constructing an array filled with default values
     pub fn new() -> GenericArray<T, N> {
         unsafe {
-            let mut res: GenericArray<T, N> = mem::uninitialized();
-            for r in res.iter_mut() { ptr::write(r, T::default()) }
-            res
+            let mut res : NoDrop<GenericArray<T, N>> = 
+                          NoDrop::new(std::mem::uninitialized());
+            for r in res.iter_mut() { 
+                ptr::write(r, T::default())
+            }
+            res.into_inner()
         }
     }
 
@@ -147,21 +180,18 @@ impl<T: Clone, N> GenericArray<T, N> where N: ArrayLength<T> {
     /// Function constructing an array from a slice; the length of the slice must be equal to the length of the array
     pub fn from_slice(list: &[T]) -> GenericArray<T, N> {
         assert_eq!(list.len(), N::to_usize());
-        unsafe {
-            let mut res: GenericArray<T, N> = mem::uninitialized();
-            for i in 0..N::to_usize() { ptr::write(&mut res[i], list[i].clone()) }
-            res
-        }
+        map_inner(list, |x: &T| x.clone())
     }
 
 }
 
 impl<T: Clone, N> Clone for GenericArray<T, N> where N: ArrayLength<T> {
     fn clone(&self) -> GenericArray<T, N> {
         unsafe {
-            let mut res: GenericArray<T, N> = mem::uninitialized();
+            let mut res : NoDrop<GenericArray<T, N>> = 
+                          NoDrop::new(std::mem::uninitialized());
             for i in 0..N::to_usize() { ptr::write(&mut res[i], self[i].clone()) }
-            res
+            res.into_inner()
         }
     }
 }