Add events, throw rather than return errors

.gitignore

@@ -0,0 +1 @@
+/node_modules

README.md

@@ -107,3 +107,13 @@ unlimited, then maxItems will be zero.
 #### .ringSize
 The size of each circular buffer. The queue will grow / shrink by this many items
 at a time.
+
+### Events
+#### ready
+The queue has one or more items stored in it.
+
+#### full
+The queue is full.
+
+#### empty
+The queue is empty.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "spique",
-  "version": "1.0.8",
+  "version": "2.0.0",
   "description": "A spiral deque - high performance and dynamic queue size",
   "main": "spique.js",
   "scripts": {
@@ -25,5 +25,8 @@
   "bugs": {
     "url": "https://github.com/erayd/spique/issues"
   },
-  "homepage": "https://github.com/erayd/spique#readme"
+  "homepage": "https://github.com/erayd/spique#readme",
+  "dependencies": {
+    "events": "^3.0.0"
+  }
 }

ringbuffer.js

@@ -0,0 +1,113 @@
+/*                                 ISC License
+ *
+ * Copyright (c) 2016-2020, Erayd LTD
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any purpose
+ * with or without fee is hereby granted, provided that the above copyright notice
+ * and this permission notice appear in all copies.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
+ * OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+
+"use strict";
+const events = require("events");
+
+module.exports = class Ringbuffer extends events.EventEmitter {
+  constructor(size) {
+    super();
+    var head = 0;
+    var items = 0;
+    var buffer = new Array(size);
+
+    // check whether the buffer is empty
+    this.isEmpty = function() {
+      return !items;
+    }
+
+    // get the number of free slots
+    this.available = function() {
+      return size - items;
+    }
+
+    // push item onto the end of the buffer
+    this.push = function(value) {
+      if(items < size) {
+        var pos = (head + items++) % size;
+        buffer[pos] = value;
+        if (items === 1)
+          this.emit("ready", this);
+        if (items === size)
+          this.emit("full", this);
+      }
+      else
+        throw new Error('Buffer is full');
+    };
+
+    // push item onto the start of the buffer
+    this.unshift = function(value) {
+      if(items < size) {
+        var pos = head ? --head : (head = size - 1);
+        buffer[pos] = value;
+        items++;
+        if (items === 1)
+          this.emit("ready", this);
+        if (items === size)
+          this.emit("full", this);
+      }
+      else
+        throw new Error('Buffer is full');
+    };
+
+    // pop an item off the end of the buffer
+    this.pop = function() {
+      if(this.isEmpty())
+        return undefined;
+      var pos = (head + --items) % size;
+      var value = buffer[pos];
+      buffer[pos] = undefined;
+      if (this.isEmpty())
+        this.emit("empty", this);
+      return value;
+    };
+
+    // pop an item off the start of the buffer
+    this.shift = function() {
+      if(this.isEmpty())
+        return undefined;
+      var value = buffer[head];
+      buffer[head] = undefined;
+      if(++head == size)
+        head = 0;
+      items--;
+      if (this.isEmpty())
+        this.emit("empty", this);
+      return value;
+    };
+
+    // peek at the end of the buffer
+    this.peek = function() {
+      if(this.isEmpty())
+        return undefined;
+      return buffer[(head + (items - 1)) % size];
+    };
+
+    // peek at the start of the buffer
+    this.peekStart = function() {
+      if(this.isEmpty())
+        return undefined;
+      return buffer[head];
+    };
+
+    // get the number of items in the buffer
+    Object.defineProperty(this, 'length', {get: function() {
+      return items;
+    }});
+  }
+}
+