first commit

app_vue/node_modules/websocket-extensions/lib/pipeline/ring_buffer.js

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+'use strict';
+
+var RingBuffer = function(bufferSize) {
+  this._bufferSize = bufferSize;
+  this.clear();
+};
+
+RingBuffer.prototype.clear = function() {
+  this._buffer     = new Array(this._bufferSize);
+  this._ringOffset = 0;
+  this._ringSize   = this._bufferSize;
+  this._head       = 0;
+  this._tail       = 0;
+  this.length      = 0;
+};
+
+RingBuffer.prototype.push = function(value) {
+  var expandBuffer = false,
+      expandRing   = false;
+
+  if (this._ringSize < this._bufferSize) {
+    expandBuffer = (this._tail === 0);
+  } else if (this._ringOffset === this._ringSize) {
+    expandBuffer = true;
+    expandRing   = (this._tail === 0);
+  }
+
+  if (expandBuffer) {
+    this._tail       = this._bufferSize;
+    this._buffer     = this._buffer.concat(new Array(this._bufferSize));
+    this._bufferSize = this._buffer.length;
+
+    if (expandRing)
+      this._ringSize = this._bufferSize;
+  }
+
+  this._buffer[this._tail] = value;
+  this.length += 1;
+  if (this._tail < this._ringSize) this._ringOffset += 1;
+  this._tail = (this._tail + 1) % this._bufferSize;
+};
+
+RingBuffer.prototype.peek = function() {
+  if (this.length === 0) return void 0;
+  return this._buffer[this._head];
+};
+
+RingBuffer.prototype.shift = function() {
+  if (this.length === 0) return void 0;
+
+  var value = this._buffer[this._head];
+  this._buffer[this._head] = void 0;
+  this.length -= 1;
+  this._ringOffset -= 1;
+
+  if (this._ringOffset === 0 && this.length > 0) {
+    this._head       = this._ringSize;
+    this._ringOffset = this.length;
+    this._ringSize   = this._bufferSize;
+  } else {
+    this._head = (this._head + 1) % this._ringSize;
+  }
+  return value;
+};
+
+module.exports = RingBuffer;