fix remove() bug introduced when inlining _bubbleDown, fix unit test …

…to catch the above, document options.freeSpace; 0.9.5

Readme.md

@@ -36,12 +36,15 @@ create a new empty heap.
 
 Options:
 
-        compar  - comparison function to determine the item ordering.  The
-                  function should return a value less than zero if the first
-                  argument should be ordered before the second (compatible
-                  with the function passed to `sort()`).
-                  The default ordering if no compar is specified is by `<`:
-                  `function(a,b){ return a < b ? -1 : 1 }`
+    compar: comparison function to determine the item ordering.  The function
+        should return a value less than zero if the first argument should be
+        ordered before the second (compatible with the function passed to
+        `sort()`).  The default ordering if no compar is specified is by `<`:
+        `function(a,b){ return a < b ?  -1 : 1 }`
+
+    freeSpace: when the heap shrinks to 1/4 its high-water mark, reallocate
+        the storage space to free the unused memory, and reset the high-water
+        mark.  Default is false, avoiding the overhead of the array slice.
 
 ### insert( item )
 
@@ -51,11 +54,12 @@ only the `compar` function needs to know the actual type.
 ### remove( )
 
 remove and return the item at the root of the heap (the next item in the
-sequence), and rebalance the tree.
+sequence), and rebalance the tree.  When empty, returns `undefined`.
 
 ### peek( )
 
-return the item at the root of the heap, but do not remove it.
+return the item at the root of the heap, but do not remove it.  When empty,
+returns `undefined`.
 
 ### length
 

lib/qheap.js

@@ -15,7 +15,7 @@ module.exports = Heap;
 function Heap( opts ) {
     opts = opts || {};
     this._comparFunc = opts.compar || function(a, b) { return a < b ? -1 : 1 };
-    this._resize = opts.resizeArray || false;
+    this._freeSpace = opts.freeSpace || false;
     this._list = new Array(1);
     this.length = 0;
 }
@@ -58,7 +58,7 @@ Heap.prototype.get = function Heap_get( ) {
     var list = this._list;
     var ret = list[1];
     if (len < 2) {
-        if (len < 1) return null;
+        if (len < 1) return undefined;
         list[1] = undefined;
         this.length = 0;
         return ret;
@@ -70,7 +70,7 @@ Heap.prototype.get = function Heap_get( ) {
 
         var idx = 1;
         var comparfn = this._comparFunc;
-        var compar = function(i, j) { comparfn(list[i], list[j]); }
+        var compar = function(i, j) { return comparfn(list[i], list[j]); }
         while (true) {
             var l = 2*idx, r = 2*idx+1;
             if (r <= len && compar(r, idx) < 0) {
@@ -93,8 +93,8 @@ Heap.prototype.get = function Heap_get( ) {
 
     if (len > 10000 && list.length > 4 * len) {
         // use slice to actually free memory; 7% slower than setting .length
-        if (this._resize) this._list = list.slice(0, this.length);
-        else list.length = this.length;
+        if (this._freeSpace) this._list = list.slice(0, this.length+1);
+        else list.length = this.length+1;
     }
 
     return ret;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "qheap",
-  "version": "0.9.4",
+  "version": "0.9.5",
   "description": "very fast binary heap priority queue",
   "license": "Apache-2.0",
   "repository": {

test/test-qheap.js

@@ -46,12 +46,16 @@ module.exports = {
 
     'should sort the data': function(t) {
         var i, data = [580, 253, 610, 176];
-        for (i=0; i<100000; i++) data[i] = Math.random() * 1000 | 0;
-        for (var i in data) {
+        for (i=0; i<100000; i++) {
+            data[i] = Math.random() * 1000 | 0;
             this.cut.put(data[i]);
         }
         var ok = this.cut._check();
         t.ok(ok);
+        t.equal(this.cut.length, data.length);
+        var item = this.cut.get();
+        while (this.cut.peek() !== undefined) { var x = this.cut.get(); assert(x >= item); item = x; }
+        t.equal(this.cut.length, 0);
         t.done();
     },
 };