---

yaml
---
r: 55164
b: refs/heads/snap-stage3
c: 6f18bb5
h: refs/heads/master
v: v3

Author: thestinger

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: 5f13e9ccc2e3328d4cd8ca49f84e6840dd998346
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 7fed4800733805156f0d157e45b01de405c4b48e
+refs/heads/snap-stage3: 6f18bb550e1293e77281b1cc76f1830a4da2d355
 refs/heads/try: 8eb2bab100b42f0ba751552d8eff00eb2134c55a
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/src/libcore/iter.rs

@@ -41,6 +41,8 @@ much easier to implement.
 
 */
 
+use option::{Option, Some, None};
+
 pub trait Times {
     fn times(&self, it: &fn() -> bool);
 }
@@ -104,6 +106,27 @@ pub fn all<T>(predicate: &fn(T) -> bool, iter: &fn(f: &fn(T) -> bool)) -> bool {
     true
 }
 
+/**
+ * Return the first element where `predicate` returns `true`, otherwise return `Npne` if no element
+ * is found.
+ *
+ * # Example:
+ *
+ * ~~~~
+ * let xs = ~[1u, 2, 3, 4, 5, 6];
+ * assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.each(f)).unwrap(), 4);
+ * ~~~~
+ */
+#[inline(always)]
+pub fn find<T>(predicate: &fn(&T) -> bool, iter: &fn(f: &fn(T) -> bool)) -> Option<T> {
+    for iter |x| {
+        if predicate(&x) {
+            return Some(x);
+        }
+    }
+    None
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -128,4 +151,10 @@ mod tests {
         assert!(all(|x: uint| x < 6, |f| uint::range(1, 6, f)));
         assert!(!all(|x: uint| x < 5, |f| uint::range(1, 6, f)));
     }
+
+    #[test]
+    fn test_find() {
+        let xs = ~[1u, 2, 3, 4, 5, 6];
+        assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.each(f)).unwrap(), 4);
+    }
 }