Add vec::filter

2 files changed, 18 insertions, 0 deletions

diff --git a/src/lib/vec.rs b/src/lib/vec.rs
index 6ca0c9bb61e..fef91259b50 100644
--- a/src/lib/vec.rs
+++ b/src/lib/vec.rs
@@ -213,6 +213,17 @@ fn filter_map<@T, @U>(f: block(T) -> option::t<U>, v: [mutable? T]) -> [U] {
     ret result;
 }
 
+fn filter<@T>(f: block(T) -> bool, v: [mutable? T]) -> [T] {
+    let result = [];
+    for elem: T in v {
+        let elem2 = elem; // satisfies alias checker
+        if f(elem2) {
+            result += [elem2];
+        }
+    }
+    ret result;
+}
+
 fn foldl<@T, @U>(p: block(U, T) -> U, z: U, v: [mutable? T]) -> U {
     let sz = len(v);
     if sz == 0u { ret z; }
diff --git a/src/test/stdtest/vec.rs b/src/test/stdtest/vec.rs
index a9cda6c73d6..b7571d5bf0e 100644
--- a/src/test/stdtest/vec.rs
+++ b/src/test/stdtest/vec.rs
@@ -12,6 +12,8 @@ fn square_alias(n: uint) -> uint { ret n * n; }
 
 pure fn is_three(n: uint) -> bool { ret n == 3u; }
 
+pure fn is_odd(n: uint) -> bool { ret n % 2u == 1u; }
+
 fn square_if_odd(n: uint) -> option::t<uint> {
     ret if n % 2u == 1u { some(n * n) } else { none };
 }
@@ -269,7 +271,12 @@ fn test_filter_map() {
     assert (filter_map(halve, all_odd1) == []);
     assert (filter_map(halve, all_odd2) == []);
     assert (filter_map(halve, mix) == mix_dest);
+}
 
+#[test]
+fn test_filter() {
+    assert filter(is_odd, [1u, 2u, 3u]) == [1u, 3u];
+    assert filter(is_three, [1u, 2u, 4u, 8u, 16u]) == [];
 }
 
 #[test]