---

yaml
---
r: 28458
b: refs/heads/try
c: 8672b90
h: refs/heads/master
v: v3

Author: brson

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
-refs/heads/try: 85768d18ee8d893cac61b61e0801d5c6f1c4b536
+refs/heads/try: 8672b9003f17b6e38a9c55f92dfc1deef91b1344
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: d0c6ce338884ee21843f4b40bf6bf18d222ce5df

branches/try/src/libcore/vec.rs

@@ -43,6 +43,7 @@ export grow;
 export grow_fn;
 export grow_set;
 export truncate;
+export dedup;
 export map;
 export mapi;
 export map2;
@@ -625,6 +626,41 @@ fn truncate<T>(&v: ~[const T], newlen: uint) {
     }
 }
 
+/**
+ * Remove consecutive repeated elements from a vector; if the vector is
+ * sorted, this removes all duplicates.
+ */
+fn dedup<T: Eq>(&v: ~[const T]) unsafe {
+    if v.len() < 1 { return; }
+    let mut last_written = 0, next_to_read = 1;
+    do as_const_buf(v) |p, ln| {
+        // We have a mutable reference to v, so we can make arbitrary changes.
+        // (cf. push and pop)
+        let p = p as *mut T;
+        // last_written < next_to_read <= ln
+        while next_to_read < ln {
+            // last_written < next_to_read < ln
+            if *ptr::mut_offset(p, next_to_read) ==
+                *ptr::mut_offset(p, last_written) {
+                let _dropped <- *ptr::mut_offset(p, next_to_read);
+            } else {
+                last_written += 1;
+                // last_written <= next_to_read < ln
+                if next_to_read != last_written {
+                    *ptr::mut_offset(p, last_written) <-
+                        *ptr::mut_offset(p, next_to_read);
+                }
+            }
+            // last_written <= next_to_read < ln
+            next_to_read += 1;
+            // last_written < next_to_read <= ln
+        }
+    }
+    // last_written < next_to_read == ln
+    unsafe::set_len(v, last_written + 1);
+}
+
+
 // Appending
 #[inline(always)]
 pure fn append<T: Copy>(+lhs: ~[T], rhs: &[const T]) -> ~[T] {
@@ -2218,6 +2254,51 @@ mod tests {
         // If the unsafe block didn't drop things properly, we blow up here.
     }
 
+    #[test]
+    fn test_dedup() {
+        fn case(-a: ~[uint], -b: ~[uint]) {
+            let mut v = a;
+            dedup(v);
+            assert(v == b);
+        }
+        case(~[], ~[]);
+        case(~[1], ~[1]);
+        case(~[1,1], ~[1]);
+        case(~[1,2,3], ~[1,2,3]);
+        case(~[1,1,2,3], ~[1,2,3]);
+        case(~[1,2,2,3], ~[1,2,3]);
+        case(~[1,2,3,3], ~[1,2,3]);
+        case(~[1,1,2,2,2,3,3], ~[1,2,3]);
+    }
+
+    #[test]
+    fn test_dedup_unique() {
+        let mut v0 = ~[~1, ~1, ~2, ~3];
+        dedup(v0);
+        let mut v1 = ~[~1, ~2, ~2, ~3];
+        dedup(v1);
+        let mut v2 = ~[~1, ~2, ~3, ~3];
+        dedup(v2);
+        /*
+         * If the ~pointers were leaked or otherwise misused, valgrind and/or
+         * rustrt should raise errors.
+         */
+    }
+
+    #[test]
+    fn test_dedup_shared() {
+        let mut v0 = ~[@1, @1, @2, @3];
+        dedup(v0);
+        let mut v1 = ~[@1, @2, @2, @3];
+        dedup(v1);
+        let mut v2 = ~[@1, @2, @3, @3];
+        dedup(v2);
+        /*
+         * If the @pointers were leaked or otherwise misused, valgrind and/or
+         * rustrt should raise errors.
+         */
+    }
+
     #[test]
     fn test_map() {
         // Test on-stack map.