Count rings as they are added / removed to make .capacity O(1)

erayd · Sep 8, 2016 · a8028f2 · a8028f2
1 parent d6237c7
commit a8028f2
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Showing 3 changed files with 8 additions and 6 deletions.
diff --git a/README.md b/README.md
@@ -3,7 +3,7 @@ Spique - A Spiral Double-Ended Queue
 
 Spique is a deque implemented as a doubly-linked list of circular buffers. This
 structure allows for both high performance and unlimited dynamic growth of the
-queue. All operations are O(1) except the `.capacity` property, which is O(n).
+queue. All operations are O(1) (constant time).
 
 Spique does not require an initial or maximum size (although you can define a
 maximum if you wish), and will both grow and shrink dynamically as items are

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "spique",
-  "version": "1.0.4",
+  "version": "1.0.5",
   "description": "A spiral deque - high performance and dynamic queue size",
   "main": "spique.js",
   "scripts": {

diff --git a/spique.js b/spique.js
@@ -23,6 +23,7 @@ function Spique(maxItems, circumference) {
 
   var firstRing = new RingBuffer(circumference);
   var lastRing = firstRing;
+  var rings = 1;
   var items = 0;
 
   // check whether the buffer is empty
@@ -41,6 +42,7 @@ function Spique(maxItems, circumference) {
         lastRing.nextRing = newRing;
         newRing.prevRing = lastRing;
         lastRing = newRing;
+        rings++;
       }
       lastRing.push(value);
       items++;
@@ -58,6 +60,7 @@ function Spique(maxItems, circumference) {
         newRing.nextRing = firstRing;
         firstRing.prevRing = newRing;
         firstRing = newRing;
+        rings++;
       }
       firstRing.unshift(value);
       items++;
@@ -71,6 +74,7 @@ function Spique(maxItems, circumference) {
     if(lastRing.isEmpty() && lastRing.prevRing) {
       lastRing = lastRing.prevRing;
       delete lastRing.nextRing;
+      rings--;
     }
     items--;
     return value;
@@ -83,6 +87,7 @@ function Spique(maxItems, circumference) {
     if(firstRing.isEmpty() && firstRing.nextRing) {
       firstRing = firstRing.nextRing;
       delete firstRing.prevRing;
+      rings--;
     }
     items--;
     return value;
@@ -111,10 +116,7 @@ function Spique(maxItems, circumference) {
 
   // get the current capacity
   Object.defineProperty(this, 'capacity', {get: function() {
-    var capacity = 0;
-    for(var r = firstRing; r; r = r.nextRing)
-      capacity += circumference;
-    return capacity;
+    return rings * circumference;
   }});
 
   // get the max number of items