Add quick sort function to the std lib.

src/lib/sort.rs

@@ -39,6 +39,58 @@ fn merge[T](lteq[T] le, vec[T] a, vec[T] b) -> vec[T] {
                  merge_sort[T](le, b));
 }
 
+fn swap[T](vec[mutable T] arr, uint x, uint y) {
+    auto a = arr.(x);
+    arr.(x) = arr.(y);
+    arr.(y) = a;
+}
+
+fn part[T](lteq[mutable T] compare_func, vec[mutable T] arr, uint left,
+        uint right, uint pivot) -> uint {
+
+    fn compare[T](lteq[mutable T] compare_func, vec[mutable T]arr,
+           uint arr_idx, &T arr_value) -> bool {
+
+        ret compare_func(arr.(arr_idx),arr_value);
+    }
+
+    auto pivot_value = arr.(pivot);
+    swap[T](arr, pivot, right);
+    let uint storage_index = left;
+    let uint i = left;
+    while (i<right) {
+        if (compare[T](compare_func, arr, i, pivot_value)) {
+           swap[T](arr, i, storage_index);
+           storage_index += 1u;
+        }
+        i += 1u;
+    }
+    swap[T](arr, storage_index, right);
+    ret storage_index;
+}
+
+fn qsort[T](lteq[mutable T] compare_func, vec[mutable T] arr, uint left,
+        uint right) {
+
+    if (right > left) {
+        auto pivot = (left+right)/2u;
+        auto new_pivot = part[T](compare_func, arr, left, right, pivot);
+        if (new_pivot == 0u) {
+             ret;
+        }
+        qsort[T](compare_func, arr, left, new_pivot - 1u);
+        qsort[T](compare_func, arr, new_pivot + 1u, right);
+    }
+}
+
+fn quick_sort[T](lteq[mutable T] compare_func, vec[mutable T] arr) {
+
+    if (len[mutable T](arr) == 0u) {
+        ret;
+    }
+    qsort[T](compare_func, arr, 0u, (len[mutable T](arr)) - 1u);
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;

src/test/run-pass/lib-qsort.rs

@@ -0,0 +1,62 @@
+use std;
+
+fn check_sort(vec[mutable int] v1, vec[mutable int] v2) {
+  auto len = std._vec.len[int](v1);
+
+  fn ltequal(&int a, &int b) -> bool {
+    ret a <= b;
+  }
+  auto f = ltequal;
+  std.sort.quick_sort[int](f, v1);
+  auto i = 0u;
+  while (i < len) {
+    log v2.(i);
+    assert (v2.(i) == v1.(i));
+    i += 1u;
+  }
+}
+
+
+fn main() {
+  {
+    auto v1 = vec(mutable 3,7,4,5,2,9,5,8);
+    auto v2 = vec(mutable 2,3,4,5,5,7,8,9);
+    check_sort(v1, v2);
+  }
+
+  {
+    auto v1 = vec(mutable 1,1,1);
+    auto v2 = vec(mutable 1,1,1);
+    check_sort(v1, v2);
+  }
+
+  {
+    let vec[mutable int] v1 = vec(mutable);
+    let vec[mutable int] v2 = vec(mutable);
+    check_sort(v1, v2);
+  }
+
+  {
+    auto v1 = vec(mutable 9);
+    auto v2 = vec(mutable 9);
+    check_sort(v1, v2);
+  }
+
+  {
+    auto v1 = vec(mutable 9,3,3,3,9);
+    auto v2 = vec(mutable 3,3,3,9,9);
+    check_sort(v1, v2);
+  }
+
+}
+
+// Local Variables:
+// mode: rust;
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+
+