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express-server/node_modules/buffer-writer/index.js

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+//binary data writer tuned for creating
+//postgres message packets as effeciently as possible by reusing the
+//same buffer to avoid memcpy and limit memory allocations
+var Writer = module.exports = function(size) {
+  this.size = size || 1024;
+  this.buffer = Buffer(this.size + 5);
+  this.offset = 5;
+  this.headerPosition = 0;
+};
+
+//resizes internal buffer if not enough size left
+Writer.prototype._ensure = function(size) {
+  var remaining = this.buffer.length - this.offset;
+  if(remaining < size) {
+    var oldBuffer = this.buffer;
+    // exponential growth factor of around ~ 1.5
+    // https://stackoverflow.com/questions/2269063/buffer-growth-strategy
+    var newSize = oldBuffer.length + (oldBuffer.length >> 1) + size;
+    this.buffer = new Buffer(newSize);
+    oldBuffer.copy(this.buffer);
+  }
+};
+
+Writer.prototype.addInt32 = function(num) {
+  this._ensure(4);
+  this.buffer[this.offset++] = (num >>> 24 & 0xFF);
+  this.buffer[this.offset++] = (num >>> 16 & 0xFF);
+  this.buffer[this.offset++] = (num >>>  8 & 0xFF);
+  this.buffer[this.offset++] = (num >>>  0 & 0xFF);
+  return this;
+};
+
+Writer.prototype.addInt16 = function(num) {
+  this._ensure(2);
+  this.buffer[this.offset++] = (num >>>  8 & 0xFF);
+  this.buffer[this.offset++] = (num >>>  0 & 0xFF);
+  return this;
+};
+
+//for versions of node requiring 'length' as 3rd argument to buffer.write
+var writeString = function(buffer, string, offset, len) {
+  buffer.write(string, offset, len);
+};
+
+//overwrite function for older versions of node
+if(Buffer.prototype.write.length === 3) {
+  writeString = function(buffer, string, offset, len) {
+    buffer.write(string, offset);
+  };
+}
+
+Writer.prototype.addCString = function(string) {
+  //just write a 0 for empty or null strings
+  if(!string) {
+    this._ensure(1);
+  } else {
+    var len = Buffer.byteLength(string);
+    this._ensure(len + 1); //+1 for null terminator
+    writeString(this.buffer, string, this.offset, len);
+    this.offset += len;
+  }
+
+  this.buffer[this.offset++] = 0; // null terminator
+  return this;
+};
+
+Writer.prototype.addChar = function(c) {
+  this._ensure(1);
+  writeString(this.buffer, c, this.offset, 1);
+  this.offset++;
+  return this;
+};
+
+Writer.prototype.addString = function(string) {
+  string = string || "";
+  var len = Buffer.byteLength(string);
+  this._ensure(len);
+  this.buffer.write(string, this.offset);
+  this.offset += len;
+  return this;
+};
+
+Writer.prototype.getByteLength = function() {
+  return this.offset - 5;
+};
+
+Writer.prototype.add = function(otherBuffer) {
+  this._ensure(otherBuffer.length);
+  otherBuffer.copy(this.buffer, this.offset);
+  this.offset += otherBuffer.length;
+  return this;
+};
+
+Writer.prototype.clear = function() {
+  this.offset = 5;
+  this.headerPosition = 0;
+  this.lastEnd = 0;
+};
+
+//appends a header block to all the written data since the last
+//subsequent header or to the beginning if there is only one data block
+Writer.prototype.addHeader = function(code, last) {
+  var origOffset = this.offset;
+  this.offset = this.headerPosition;
+  this.buffer[this.offset++] = code;
+  //length is everything in this packet minus the code
+  this.addInt32(origOffset - (this.headerPosition+1));
+  //set next header position
+  this.headerPosition = origOffset;
+  //make space for next header
+  this.offset = origOffset;
+  if(!last) {
+    this._ensure(5);
+    this.offset += 5;
+  }
+};
+
+Writer.prototype.join = function(code) {
+  if(code) {
+    this.addHeader(code, true);
+  }
+  return this.buffer.slice(code ? 0 : 5, this.offset);
+};
+
+Writer.prototype.flush = function(code) {
+  var result = this.join(code);
+  this.clear();
+  return result;
+};