Avoid excessive allocations and copies in iter::to_vec

dotdash · dotdash · commit a26d9db95f2f · 2013-04-13T14:29:14.000+02:00
The foldl based implementation allocates lots of unneeded vectors.
iter::map_to_vec is already optimized to avoid these.
diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs
@@ -161,7 +161,7 @@ pub fn foldl<A,B,IA:BaseIter<A>>(self: &IA, b0: B, blk: &fn(&B, &A) -> B)
 
 #[inline(always)]
 pub fn to_vec<A:Copy,IA:BaseIter<A>>(self: &IA) -> ~[A] {
-    foldl::<A,~[A],IA>(self, ~[], |r, a| vec::append(copy (*r), ~[*a]))
+    map_to_vec(self, |&x| x)
 }
 
 #[inline(always)]

Original file line number	Diff line number	Diff line change
`@@ -161,7 +161,7 @@ pub fn foldl<A,B,IA:BaseIter<A>>(self: &IA, b0: B, blk: &fn(&B, &A) -> B)`
`161`	`161`
`162`	`162`	`#[inline(always)]`
`163`	`163`	`pub fn to_vec<A:Copy,IA:BaseIter<A>>(self: &IA) -> ~[A] {`
`164`		`- foldl::<A,~[A],IA>(self, ~[], \|r, a\| vec::append(copy (r), ~[a]))`
	`164`	`+ map_to_vec(self, \|&x\| x)`
`165`	`165`	`}`
`166`	`166`
`167`	`167`	`#[inline(always)]`