Migrate some heap operations to std.algorithm

std/algorithm/sorting.d

@@ -1123,7 +1123,7 @@ private void quickSortImpl(alias less, Range)(Range r, size_t depth)
     {
         if (depth == 0)
         {
-            HeapSortImpl!(less, Range).heapSort(r);
+            HeapOps!(less, Range).heapSort(r);
             return;
         }
         depth = depth >= depth.max / 2 ? (depth / 3) * 2 : (depth * 2) / 3;
@@ -1167,8 +1167,8 @@ private void quickSortImpl(alias less, Range)(Range r, size_t depth)
     }
 }
 
-// Bottom-Up Heap-Sort Implementation
-private template HeapSortImpl(alias less, Range)
+// Heap operations for random-access ranges
+package(std) template HeapOps(alias less, Range)
 {
     import std.algorithm.mutation : swapAt;
 
@@ -1185,21 +1185,27 @@ private template HeapSortImpl(alias less, Range)
         if(r.length < 2) return;
 
         // Build Heap
-        size_t i = r.length / 2;
-        while(i > 0) sift(r, --i, r.length);
+        heapify(r);
 
         // Sort
-        i = r.length - 1;
+        size_t i = r.length - 1;
         while(i > 0)
         {
             swapAt(r, 0, i);
-            sift(r, 0, i);
+            percolate(r, 0, i);
             --i;
         }
     }
     
     //template because of @@@12410@@@
-    void sift()(Range r, size_t parent, immutable size_t end)
+    void heapify()(Range r)
+    {
+        size_t i = r.length / 2;
+        while(i > 0) percolate(r, --i, r.length);
+    }
+
+    //template because of @@@12410@@@
+    void percolate()(Range r, size_t parent, immutable size_t end)
     {
         immutable root = parent;
         size_t child = void;

std/container/binaryheap.d

@@ -59,9 +59,12 @@ if (isRandomAccessRange!(Store) || isRandomAccessRange!(typeof(Store.init[])))
 {
     import std.functional : binaryFun;
     import std.exception : enforce;
-    import std.algorithm : move, min;
+    import std.algorithm : move, min, HeapOps, swapAt;
     import std.typecons : RefCounted, RefCountedAutoInitialize;
     
+    alias percolate = HeapOps!(less, Store).percolate;
+    alias heapify = HeapOps!(less, Store).heapify;
+
 // Really weird @@BUG@@: if you comment out the "private:" label below,
 // std.algorithm can't unittest anymore
 //private:
@@ -103,40 +106,6 @@ if (isRandomAccessRange!(Store) || isRandomAccessRange!(typeof(Store.init[])))
         }
     }
 
-    // Assuming the element at "parent" perturbs the heap property in
-    // store r, percolates it down the heap such that the heap
-    // property is restored.
-    private void percolate(Store r, size_t parent, immutable size_t end)
-    {
-        immutable root = parent;
-        size_t child = void;
-        
-        // Sift down
-        for (;;)
-        {
-            child = parent * 2 + 1;
-            if (child >= end) break;
-            if (child + 1 < end && comp(r[child], r[child + 1])) child += 1;
-            
-            swap(r, parent, child);
-            parent = child;
-        }
-        
-        child = parent;
-        
-        // Sift up
-        while (child > root)
-        {
-            parent = (child - 1) / 2;
-            if (comp(r[parent], r[child]))
-            {
-                swap(r, parent, child);
-                child = parent;
-            }
-            else break;
-        }
-    }
-
     // @@@BUG@@@: add private here, std.algorithm doesn't unittest anymore
     /*private*/ void pop(Store store)
     {
@@ -149,28 +118,6 @@ if (isRandomAccessRange!(Store) || isRandomAccessRange!(typeof(Store.init[])))
         percolate(store, 0, store.length - 1);
     }
 
-    /*private*/ static void swap(Store _store, size_t i, size_t j)
-    {
-        static if (is(typeof(swap(_store[i], _store[j]))))
-        {
-            swap(_store[i], _store[j]);
-        }
-        else static if (is(typeof(_store.moveAt(i))))
-        {
-            auto t1 = _store.moveAt(i);
-            auto t2 = _store.moveAt(j);
-            _store[i] = move(t2);
-            _store[j] = move(t1);
-        }
-        else // assume it's a container and access its range with []
-        {
-            auto t1 = _store[].moveAt(i);
-            auto t2 = _store[].moveAt(j);
-            _store[i] = move(t2);
-            _store[j] = move(t1);
-        }
-    }
-
 public:
 
     /**
@@ -196,11 +143,7 @@ the heap work incorrectly.
         _store = move(s);
         _length = min(_store.length, initialSize);
         if (_length < 2) return;
-        for (auto i = (_length - 2) / 2; ; )
-        {
-            this.percolate(_store, i, _length);
-            if (i-- == 0) break;
-        }
+        heapify(s);
         assertValid();
     }
 
@@ -330,7 +273,7 @@ and $(D length == capacity), throws an exception.
             auto parentIdx = (n - 1) / 2;
             if (!comp(_store[parentIdx], _store[n])) break; // done!
             // must swap and continue
-            swap(_store, parentIdx, n);
+            swapAt(_store, parentIdx, n);
             n = parentIdx;
         }
         ++_length;