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