113 lines
3.1 KiB
Markdown
113 lines
3.1 KiB
Markdown
|
ternary-stream 
|
||
|
|
=======
|
||
|
|
|
||
|
|
A ternary stream: conditionally control the flow of stream data
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
1: Conditionally filter content
|
||
|
|
|
||
|
|
**Condition**
|
||
|
|
|
||
|
|
![][condition]
|
||
|
|
|
||
|
|
if the condition returns truthy, data is piped to the child stream
|
||
|
|
|
||
|
|
```js
|
||
|
|
var ternaryStream = require('ternary-stream');
|
||
|
|
|
||
|
|
var condition = function (data) {
|
||
|
|
return true;
|
||
|
|
};
|
||
|
|
|
||
|
|
process.stdin
|
||
|
|
.pipe(ternaryStream(condition, process.stdout))
|
||
|
|
.pipe(fs.createWriteStream('./out.txt'));
|
||
|
|
```
|
||
|
|
|
||
|
|
Data will conditionally go to stdout, and always go to the file
|
||
|
|
|
||
|
|
2: Ternary stream
|
||
|
|
|
||
|
|
**Ternary**
|
||
|
|
|
||
|
|
![][ternary]
|
||
|
|
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var ternaryStream = require('ternary-stream');
|
||
|
|
var through2 = require('through2');
|
||
|
|
|
||
|
|
var count = 0;
|
||
|
|
var condition = function (data) {
|
||
|
|
count++;
|
||
|
|
return count % 2;
|
||
|
|
};
|
||
|
|
|
||
|
|
process.stdin
|
||
|
|
.pipe(ternaryStream(condition, fs.createWriteStream('./truthy.txt'), fs.createWriteStream('./falsey.txt')))
|
||
|
|
.pipe(process.stdout);
|
||
|
|
```
|
||
|
|
|
||
|
|
Data will either go to truthy.txt (if condition is true) or falsey.txt (if condition is false) and will always go to stdout
|
||
|
|
|
||
|
|
## API
|
||
|
|
|
||
|
|
### ternaryStream(condition, stream [, elseStream])
|
||
|
|
|
||
|
|
ternary-stream will pipe data to `stream` whenever `condition` is truthy.
|
||
|
|
|
||
|
|
If `condition` is falsey and `elseStream` is passed, data will pipe to `elseStream`.
|
||
|
|
|
||
|
|
After data is piped to `stream` or `elseStream` or neither, data is piped down-stream.
|
||
|
|
|
||
|
|
#### Parameters
|
||
|
|
|
||
|
|
##### condition
|
||
|
|
|
||
|
|
Type: `function`: takes in stream data and returns `boolean`
|
||
|
|
|
||
|
|
```js
|
||
|
|
function (data) {
|
||
|
|
return true; // or false
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
##### stream
|
||
|
|
|
||
|
|
Stream for ternary-stream to pipe data into when condition is truthy.
|
||
|
|
|
||
|
|
##### elseStream
|
||
|
|
|
||
|
|
Optional, Stream for ternary-stream to pipe data into when condition is falsey.
|
||
|
|
|
||
|
|
|
||
|
|
LICENSE
|
||
|
|
-------
|
||
|
|
|
||
|
|
(MIT License)
|
||
|
|
|
||
|
|
Copyright (c) 2014 [Richardson & Sons, LLC](http://richardsonandsons.com/)
|
||
|
|
|
||
|
|
Permission is hereby granted, free of charge, to any person obtaining
|
||
|
|
a copy of this software and associated documentation files (the
|
||
|
|
"Software"), to deal in the Software without restriction, including
|
||
|
|
without limitation the rights to use, copy, modify, merge, publish,
|
||
|
|
distribute, sublicense, and/or sell copies of the Software, and to
|
||
|
|
permit persons to whom the Software is furnished to do so, subject to
|
||
|
|
the following conditions:
|
||
|
|
|
||
|
|
The above copyright notice and this permission notice shall be
|
||
|
|
included in all copies or substantial portions of the Software.
|
||
|
|
|
||
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
||
|
|
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
||
|
|
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
||
|
|
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
|
||
|
|
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
|
||
|
|
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
|
||
|
|
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
||
|
|
|
||
|
|
[condition]: https://rawgithub.com/robrich/ternary-stream/master/img/condition.svg
|
||
|
|
[ternary]: https://rawgithub.com/robrich/ternary-stream/master/img/ternary.svg
|