www.aleph1.co.uk Git - yaffs-website/blob - node_modules/first-chunk-stream/index.js

   1 'use strict';
   2 var util = require('util');
   3 var Transform = require('stream').Transform;
   4
   5 function ctor(options, transform) {
   6         util.inherits(FirstChunk, Transform);
   7
   8         if (typeof options === 'function') {
   9                 transform = options;
  10                 options = {};
  11         }
  12
  13         if (typeof transform !== 'function') {
  14                 throw new Error('transform function required');
  15         }
  16
  17         function FirstChunk(options2) {
  18                 if (!(this instanceof FirstChunk)) {
  19                         return new FirstChunk(options2);
  20                 }
  21
  22                 Transform.call(this, options2);
  23
  24                 this._firstChunk = true;
  25                 this._transformCalled = false;
  26                 this._minSize = options.minSize;
  27         }
  28
  29         FirstChunk.prototype._transform = function (chunk, enc, cb) {
  30                 this._enc = enc;
  31
  32                 if (this._firstChunk) {
  33                         this._firstChunk = false;
  34
  35                         if (this._minSize == null) {
  36                                 transform.call(this, chunk, enc, cb);
  37                                 this._transformCalled = true;
  38                                 return;
  39                         }
  40
  41                         this._buffer = chunk;
  42                         cb();
  43                         return;
  44                 }
  45
  46                 if (this._minSize == null) {
  47                         this.push(chunk);
  48                         cb();
  49                         return;
  50                 }
  51
  52                 if (this._buffer.length < this._minSize) {
  53                         this._buffer = Buffer.concat([this._buffer, chunk]);
  54                         cb();
  55                         return;
  56                 }
  57
  58                 if (this._buffer.length >= this._minSize) {
  59                         transform.call(this, this._buffer.slice(), enc, function () {
  60                                 this.push(chunk);
  61                                 cb();
  62                         }.bind(this));
  63                         this._transformCalled = true;
  64                         this._buffer = false;
  65                         return;
  66                 }
  67
  68                 this.push(chunk);
  69                 cb();
  70         };
  71
  72         FirstChunk.prototype._flush = function (cb) {
  73                 if (!this._buffer) {
  74                         cb();
  75                         return;
  76                 }
  77
  78                 if (this._transformCalled) {
  79                         this.push(this._buffer);
  80                         cb();
  81                 } else {
  82                         transform.call(this, this._buffer.slice(), this._enc, cb);
  83                 }
  84         };
  85
  86         return FirstChunk;
  87 }
  88
  89 module.exports = function () {
  90         return ctor.apply(ctor, arguments)();
  91 };
  92
  93 module.exports.ctor = ctor;