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Use native stream module for Transform to use its full feature #3

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Use native stream module for Transform to use its full feature #3

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084e3ad
use const and let
piglovesyou Feb 3, 2018
b04240b
use class
piglovesyou Feb 3, 2018
1ea259d
it works with native Transform
piglovesyou Feb 3, 2018
1356867
rm unused deps
piglovesyou Feb 3, 2018
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178 changes: 89 additions & 89 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,105 +1,105 @@
var Transform = require('readable-stream').Transform;
var inherits = require('inherits');
var cyclist = require('cyclist');
var util = require('util');

var ParallelTransform = function(maxParallel, opts, ontransform) {
if (!(this instanceof ParallelTransform)) return new ParallelTransform(maxParallel, opts, ontransform);
const {Transform} = require('stream');
const cyclist = require('cyclist');

class ParallelTransform extends Transform {
constructor(maxParallel, opts, ontransform) {
if (typeof maxParallel === 'function') {
ontransform = maxParallel;
opts = null;
maxParallel = 1;
}
if (typeof opts === 'function') {
ontransform = opts;
opts = null;
}

if (typeof maxParallel === 'function') {
ontransform = maxParallel;
opts = null;
maxParallel = 1;
if (!opts) opts = {};
if (!opts.highWaterMark) opts.highWaterMark = Math.max(maxParallel, 16);
if (opts.objectMode !== false) opts.objectMode = true;

super(opts);

this._maxParallel = maxParallel;
this._ontransform = ontransform;
this._destroyed = false;
this._flushed = false;
this._ordered = opts.ordered !== false;
this._buffer = this._ordered ? cyclist(maxParallel) : [];
this._top = 0;
this._bottom = 0;
this._ondrain = null;
}
if (typeof opts === 'function') {
ontransform = opts;
opts = null;
}

if (!opts) opts = {};
if (!opts.highWaterMark) opts.highWaterMark = Math.max(maxParallel, 16);
if (opts.objectMode !== false) opts.objectMode = true;

Transform.call(this, opts);

this._maxParallel = maxParallel;
this._ontransform = ontransform;
this._destroyed = false;
this._flushed = false;
this._ordered = opts.ordered !== false;
this._buffer = this._ordered ? cyclist(maxParallel) : [];
this._top = 0;
this._bottom = 0;
this._ondrain = null;
};

inherits(ParallelTransform, Transform);
destroy() {
if (this._destroyed) return;
this._destroyed = true;
this.emit('close');
}

ParallelTransform.prototype.destroy = function() {
if (this._destroyed) return;
this._destroyed = true;
this.emit('close');
};
_transform (chunk, enc, callback) {
const self = this;
const pos = this._top++;

this._ontransform(chunk, function(err, data) {
if (self._destroyed) return;
if (err) {
self.emit('error', err);
self.push(null);
self.destroy();
return;
}
if (self._ordered) {
self._buffer.put(pos, (data === undefined || data === null) ? null : data);
}
else {
self._buffer.push(data);
}
self._drain();
});

if (this._top - this._bottom < this._maxParallel) return callback();
this._ondrain = callback;
}

ParallelTransform.prototype._transform = function(chunk, enc, callback) {
var self = this;
var pos = this._top++;
_flush (callback) {
this._flushed = true;
this._ondrain = callback;
this._drain();
}

this._ontransform(chunk, function(err, data) {
if (self._destroyed) return;
if (err) {
self.emit('error', err);
self.push(null);
self.destroy();
return;
}
if (self._ordered) {
self._buffer.put(pos, (data === undefined || data === null) ? null : data);
_drain () {
let data;
if (this._ordered) {
while (this._buffer.get(this._bottom) !== undefined) {
data = this._buffer.del(this._bottom++);
if (data === null) continue;
this.push(data);
}
}
else {
self._buffer.push(data);
while (this._buffer.length > 0) {
data = this._buffer.pop();
this._bottom++;
if (data === null) continue;
this.push(data);
}
}
self._drain();
});

if (this._top - this._bottom < this._maxParallel) return callback();
this._ondrain = callback;
};

ParallelTransform.prototype._flush = function(callback) {
this._flushed = true;
this._ondrain = callback;
this._drain();
};
if (!this._drained() || !this._ondrain) return;

ParallelTransform.prototype._drain = function() {
if (this._ordered) {
while (this._buffer.get(this._bottom) !== undefined) {
var data = this._buffer.del(this._bottom++);
if (data === null) continue;
this.push(data);
}
const ondrain = this._ondrain;
this._ondrain = null;
ondrain();
}
else {
while (this._buffer.length > 0) {
var data = this._buffer.pop();
this._bottom++;
if (data === null) continue;
this.push(data);
}
}


if (!this._drained() || !this._ondrain) return;

var ondrain = this._ondrain;
this._ondrain = null;
ondrain();
};
_drained () {
let diff = this._top - this._bottom;
return this._flushed ? !diff : diff < this._maxParallel;
};
}

ParallelTransform.prototype._drained = function() {
var diff = this._top - this._bottom;
return this._flushed ? !diff : diff < this._maxParallel;
module.exports = function parallelTransform(maxParallel, opts, ontransform) {
return new ParallelTransform(maxParallel, opts, ontransform);
};

module.exports = ParallelTransform;
module.exports.ParallelTransform = ParallelTransform;
4 changes: 1 addition & 3 deletions package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,6 @@
],
"author": "Mathias Buus Madsen <[email protected]>",
"dependencies": {
"cyclist": "~0.2.2",
"inherits": "^2.0.3",
"readable-stream": "^2.1.5"
"cyclist": "~0.2.2"
}
}