Implement a map2() function in std._vec

2 files changed, 36 insertions, 1 deletions

diff --git a/src/lib/_vec.rs b/src/lib/_vec.rs
index 6fa0ed425ac..2ffe8bad08b 100644
--- a/src/lib/_vec.rs
+++ b/src/lib/_vec.rs
@@ -1,6 +1,8 @@
 import vbuf = rustrt.vbuf;
 import std.option;
 
+type operator2[T,U,V] = fn(&T, &U) -> V;
+
 native "rust" mod rustrt {
     type vbuf;
 
@@ -142,6 +144,22 @@ fn map[T, U](&option.operator[T,U] f, &vec[T] v) -> vec[U] {
     ret u;
 }
 
+fn map2[T,U,V](&operator2[T,U,V] f, &vec[T] v0, &vec[U] v1) -> vec[V] {
+    auto v0_len = len[T](v0);
+    if (v0_len != len[U](v1)) {
+        fail;
+    }
+
+    let vec[V] u = alloc[V](v0_len);
+    auto i = 0u;
+    while (i < v0_len) {
+        u += f(v0.(i), v1.(i));
+        i += 1u;
+    }
+
+    ret u;
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;
diff --git a/src/test/run-pass/lib-vec.rs b/src/test/run-pass/lib-vec.rs
index 815a3aa210a..4d6166483bc 100644
--- a/src/test/run-pass/lib-vec.rs
+++ b/src/test/run-pass/lib-vec.rs
@@ -37,7 +37,21 @@ fn test_map() {
   let vec[int] s = std._vec.map[int, int](op, v);
   let int i = 0;
   while (i < 5) {
-    check (v.(i) == s.(i));
+    check (v.(i) * v.(i) == s.(i));
+    i += 1;
+  }
+}
+
+fn test_map2() {
+  fn times(&int x, &int y) -> int { ret x * y; }
+  auto f = times;
+  auto v0 = vec(1, 2, 3, 4, 5);
+  auto v1 = vec(5, 4, 3, 2, 1);
+  auto u = std._vec.map2[int,int,int](f, v0, v1);
+
+  auto i = 0;
+  while (i < 5) {
+    check (v0.(i) * v1.(i) == u.(i));
     i += 1;
   }
 }
@@ -46,4 +60,7 @@ fn main() {
   test_init_elt();
   test_init_fn();
   test_slice();
+  test_map();
+  test_map2();
 }
+