Memoize path

mhluska · Jun 12, 2016 · 85baf80 · 85baf80
1 parent 7dcd2fa
commit 85baf80
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Showing 2 changed files with 14 additions and 14 deletions.
diff --git a/source/queue.js b/source/queue.js
@@ -1,7 +1,7 @@
 // TODO(maros): Implement using linked list if widely used.
 class Queue {
-  constructor(data = [], maxSize = Infinity) {
-    this._data    = data;
+  constructor(data, maxSize = Infinity) {
+    this._data    = data || [];
     this._maxSize = maxSize;
   }
 

diff --git a/source/snake.js b/source/snake.js
@@ -135,26 +135,26 @@ module.exports = class Snake {
       return false;
     }
 
-    this.world.enable(this.position);
+    // Recompute path.
+    if (this._path.empty() || Voxel.findOrCreate(this._path.peek()).type === 'snake') {
 
-    // Find new target.
-    let start = Voxel.findOrCreate(this.position);
-    let path  = Graph.dijkstra(start, node => node.type === 'food');
+      this.world.enable(this.position);
 
-    this.world.disable(this.position, 'snake');
+      // Find new target.
+      const start = Voxel.findOrCreate(this.position);
+      this._path  = new Queue(Graph.dijkstra(start, node => node.type === 'food'));
 
-    if (!path) {
-      return false;
-    }
+      // Remove the current position.
+      this._path.dequeue();
 
-    path.shift();
+      this.world.disable(this.position, 'snake');
+    }
 
-    if (path.length === 0) {
+    if (this._path.empty()) {
       return false;
     }
 
-    // TODO(maros): Memoize path.
-    return path[0].position;
+    return this._path.dequeue().position;
   }
 
   _nextPositionManual() {