time-to-botec

README.md (7405B)

---

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 @license Apache-2.0
 
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 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
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 See the License for the specific language governing permissions and
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 # Constant Stream
 
 > Create a [readable stream][readable-stream] which always streams the same value.
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var constantStream = require( '@stdlib/streams/node/from-constant' );
 ```
 
 <a name="constant-stream"></a>
 
 #### constantStream( value\[, options] )
 
 Returns a [readable stream][readable-stream] which **always** streams the **same** `value`.
 
 ```javascript
 var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 
 var iStream;
 var stream;
 
 function log( chunk, i ) {
     console.log( chunk.toString() );
     if ( i === 10 ) {
         stream.destroy();
     }
 }
 
 stream = constantStream( 'beep' );
 iStream = inspectStream( log );
 
 stream.pipe( iStream );
 ```
 
 The function accepts the following `options`:
 
 -   **objectMode**: specifies whether a [stream][stream] should operate in [objectMode][object-mode]. Default: `false`.
 -   **encoding**: specifies how `Buffer` objects should be decoded to `strings`. Default: `null`.
 -   **highWaterMark**: specifies the maximum number of bytes to store in an internal buffer before pausing streaming.
 -   **sep**: separator used to join streamed data. This option is only applicable when a stream is **not** in [objectMode][object-mode]. Default: `'\n'`.
 -   **iter**: number of iterations.
 
 To set [stream][stream] `options`,
 
 ```javascript
 var opts = {
     'objectMode': true,
     'encoding': 'utf8',
     'highWaterMark': 64
 };
 
 var stream = constantStream( 'beep', opts );
 ```
 
 By default, the function returns a [stream][stream] which streams an infinite number of values (i.e., the [stream][stream] will **never** end). To limit the number of streamed values, set the `iter` option.
 
 ```javascript
 var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 
 function log( chunk ) {
     console.log( chunk.toString() );
 }
 
 var opts = {
     'iter': 10
 };
 
 var stream = constantStream( 'beep', opts );
 var iStream = inspectStream( log );
 
 stream.pipe( iStream );
 ```
 
 By default, when not operating in [objectMode][object-mode], a returned [stream][stream] delineates streamed values using a newline character. To specify an alternative separator, set the `sep` option.
 
 ```javascript
 var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 
 function log( chunk ) {
     console.log( chunk.toString() );
 }
 
 var opts = {
     'iter': 10,
     'sep': ','
 };
 
 var stream = constantStream( 'beep', opts );
 var iStream = inspectStream( log );
 
 stream.pipe( iStream );
 ```
 
 * * *
 
 #### constantStream.factory( \[value, ]\[options] )
 
 Returns a `function` for creating [readable streams][readable-stream] which **always** stream the **same** provided `value`.
 
 ```javascript
 var opts = {
     'objectMode': true,
     'encoding': 'utf8',
     'highWaterMark': 64
 };
 
 var createStream = constantStream.factory( opts );
 ```
 
 If provided a `value` to stream, the returned function returns [readable streams][readable-stream] which **always** stream the **same** `value`.
 
 ```javascript
 var createStream = constantStream.factory( 'beep' );
 
 var stream1 = createStream();
 var stream2 = createStream();
 // ...
 ```
 
 If not provided a `value` to stream, the returned function requires that a `value` be provided at each invocation.
 
 ```javascript
 var createStream = constantStream.factory();
 
 var stream1 = createStream( 'beep' );
 var stream2 = createStream( 'boop' );
 // ...
 ```
 
 The method accepts the same `options` as [`constantStream()`](#constant-stream).
 
 * * *
 
 #### constantStream.objectMode( value\[, options] )
 
 This method is a convenience function to create [streams][stream] which **always** operate in [objectMode][object-mode].
 
 ```javascript
 var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 
 function log( v ) {
     console.log( v );
 }
 
 var value = {
     'beep': 'boop'
 };
 var opts = {
     'iter': 10
 };
 var stream = constantStream.objectMode( value, opts );
 
 opts = {
     'objectMode': true
 };
 var iStream = inspectStream( opts, log );
 
 stream.pipe( iStream );
 ```
 
 This method accepts the same `options` as [`constantStream()`](#constant-stream); however, the method will **always** override the [`objectMode`][object-mode] option in `options`.
 
 </section>
 
 <!-- /.usage -->
 
 * * *
 
 <section class="notes">
 
 ## Notes
 
 -   In binary mode, a provided `value` must be a `string`, `Buffer`, or `Uint8Array`.
 -   In [`objectMode`][object-mode], `null` is a reserved value. If provided `null`, the returned [stream][stream] will prematurely end.
 -   If provided an `object` reference, the `value` is **not** copied. To avoid unwanted mutation, copy the `value` **before** creating a [stream][stream].
 -   In older Node.js environments, `Uint8Array` contents may be copied to a new `Buffer` object due to changes in the underlying Node.js APIs.
 -   If the `factory` method is provided only one argument and that argument is an `object` (either empty or not containing any recognized `options` properties), the method treats the argument as a value to be streamed, **not** as an `options` argument.
 
 </section>
 
 <!-- /.notes -->
 
 * * *
 
 <section class="examples">
 
 ## Examples
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
 var constantStream = require( '@stdlib/streams/node/from-constant' );
 
 function log( v ) {
     console.log( v.toString() );
 }
 
 var opts = {
     'objectMode': true,
     'iter': 10
 };
 
 var stream = constantStream( 3.14, opts );
 
 opts = {
     'objectMode': true
 };
 var iStream = inspectStream( opts, log );
 
 stream.pipe( iStream );
 ```
 
 </section>
 
 <!-- /.examples -->
 
 <!-- Section for describing a command-line interface. -->
 
 * * *
 
 <section class="cli">
 
 ## CLI
 
 <!-- CLI usage documentation. -->
 
 <section class="usage">
 
 ### Usage
 
 ```text
 Usage: constant-stream [options] <value>
 
 Options:
 
   -h,  --help               Print this message.
   -V,  --version            Print the package version.
        --sep sep            Separator used to join streamed data. Default: '\n'.
   -n,  --iter iterations    Number of iterations.
 ```
 
 </section>
 
 <!-- /.usage -->
 
 <!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="notes">
 
 ### Notes
 
 -   In accordance with POSIX convention, a trailing newline is **always** appended to generated output prior to exit.
 
 </section>
 
 <!-- /.notes -->
 
 <!-- CLI usage examples. -->
 
 <section class="examples">
 
 ### Examples
 
 ```bash
 $ constant-stream 'beep' -n 10
 ```
 
 </section>
 
 <!-- /.examples -->
 
 </section>
 
 <!-- /.cli -->
 
 <section class="links">
 
 [stream]: https://nodejs.org/api/stream.html
 
 [object-mode]: https://nodejs.org/api/stream.html#stream_object_mode
 
 [readable-stream]: https://nodejs.org/api/stream.html
 
 </section>
 
 <!-- /.links -->