| 'use strict'; |
| |
| var Buffer = require('safe-buffer').Buffer; |
| |
| var StreamReader = function() { |
| this._queue = []; |
| this._queueSize = 0; |
| this._offset = 0; |
| }; |
| |
| StreamReader.prototype.put = function(buffer) { |
| if (!buffer || buffer.length === 0) return; |
| if (!Buffer.isBuffer(buffer)) buffer = Buffer.from(buffer); |
| this._queue.push(buffer); |
| this._queueSize += buffer.length; |
| }; |
| |
| StreamReader.prototype.read = function(length) { |
| if (length > this._queueSize) return null; |
| if (length === 0) return Buffer.alloc(0); |
| |
| this._queueSize -= length; |
| |
| var queue = this._queue, |
| remain = length, |
| first = queue[0], |
| buffers, buffer; |
| |
| if (first.length >= length) { |
| if (first.length === length) { |
| return queue.shift(); |
| } else { |
| buffer = first.slice(0, length); |
| queue[0] = first.slice(length); |
| return buffer; |
| } |
| } |
| |
| for (var i = 0, n = queue.length; i < n; i++) { |
| if (remain < queue[i].length) break; |
| remain -= queue[i].length; |
| } |
| buffers = queue.splice(0, i); |
| |
| if (remain > 0 && queue.length > 0) { |
| buffers.push(queue[0].slice(0, remain)); |
| queue[0] = queue[0].slice(remain); |
| } |
| return Buffer.concat(buffers, length); |
| }; |
| |
| StreamReader.prototype.eachByte = function(callback, context) { |
| var buffer, n, index; |
| |
| while (this._queue.length > 0) { |
| buffer = this._queue[0]; |
| n = buffer.length; |
| |
| while (this._offset < n) { |
| index = this._offset; |
| this._offset += 1; |
| callback.call(context, buffer[index]); |
| } |
| this._offset = 0; |
| this._queue.shift(); |
| } |
| }; |
| |
| module.exports = StreamReader; |