time-to-botec/js/node_modules/@stdlib/streams/node/join/lib/main.js
NunoSempere b6addc7f05 feat: add the node modules
Necessary in order to clearly see the squiggle hotwiring.
2022-12-03 12:44:49 +00:00

249 lines
6.9 KiB
JavaScript

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var Transform = require( 'readable-stream' ).Transform;
var string2buffer = require( '@stdlib/buffer/from-string' );
var copy = require( '@stdlib/utils/copy' );
var inherit = require( '@stdlib/utils/inherit' );
var Buffer = require( '@stdlib/buffer/ctor' );
var setNonEnumerable = require( '@stdlib/utils/define-nonenumerable-property' );
var setNonEnumerableReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
var nextTick = require( '@stdlib/utils/next-tick' );
var DEFAULTS = require( './defaults.json' );
var validate = require( './validate.js' );
var debug = require( './debug.js' );
// FUNCTIONS //
/**
* Implements the `_transform` method.
*
* @private
* @param {(Uint8Array|Buffer|string)} chunk - streamed chunk
* @param {string} encoding - Buffer encoding
* @param {Callback} clbk - callback to invoke after transforming the streamed chunk
*/
function transform( chunk, encoding, clbk ) {
/* eslint-disable no-invalid-this */
var len;
this._idx += 1;
debug( 'Received a new chunk. Chunk: %s. Encoding: %s. Index: %d.', chunk.toString(), encoding, this._idx );
if ( this._encoding === 'utf8' ) {
if ( this._init ) {
chunk = this._sep + chunk;
} else {
this._init = true;
}
} else if ( this._init ) {
chunk = new Buffer( chunk, encoding ); // eslint-disable-line no-buffer-constructor
len = this._sep.length + chunk.length;
chunk = Buffer.concat( [ this._sep, chunk ], len ); // TODO: replace with stdlib pkg
chunk = chunk.toString( this._encoding );
} else {
this._init = true;
}
this.push( chunk, this._encoding );
clbk();
/* eslint-enable no-invalid-this */
}
/**
* Implements the `_flush` method.
*
* @private
* @param {Callback} clbk - callback to invoke after performing flush tasks
*/
function flush( clbk ) {
debug( 'Flushing the stream...' );
clbk(); // TODO: consider supporting an option to append a final separator
}
/**
* Gracefully destroys a stream, providing backward compatibility.
*
* @private
* @param {Object} [error] - optional error message
* @returns {JoinStream} Stream instance
*/
function destroy( error ) {
/* eslint-disable no-invalid-this */
var self;
if ( this._destroyed ) {
debug( 'Attempted to destroy an already destroyed stream.' );
return this;
}
self = this;
this._destroyed = true;
nextTick( close );
return this;
/**
* Closes a stream.
*
* @private
*/
function close() {
if ( error ) {
debug( 'Stream was destroyed due to an error. Error: %s.', JSON.stringify( error ) );
self.emit( 'error', error );
}
debug( 'Closing the stream...' );
self.emit( 'close' );
}
/* eslint-enable no-invalid-this */
}
// MAIN //
/**
* Join stream constructor.
*
* @constructor
* @param {Options} [options] - stream options
* @param {string} [options.sep='\n'] - separator used to join streamed data
* @param {boolean} [options.objectMode=false] - specifies whether the stream should operate in object mode
* @param {(string|null)} [options.encoding=null] - specifies how `Buffer` objects should be decoded to `strings`
* @param {NonNegativeNumber} [options.highWaterMark] - specifies the `Buffer` level for when `write()` starts returning `false`
* @param {boolean} [options.allowHalfOpen=false] - specifies whether the stream should remain open even if one side ends
* @param {boolean} [options.readableObjectMode=false] - specifies whether the readable side should be in object mode
* @throws {TypeError} options argument must be an object
* @throws {TypeError} must provide valid options
* @returns {JoinStream} join stream
*
* @example
* var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
*
* function log( chunk ) {
* console.log( chunk );
* }
*
* var stream = new JoinStream();
*
* stream.pipe( inspectStream( log ) );
*
* stream.write( '1' );
* stream.write( '2' );
* stream.write( '3' );
*
* stream.end();
*
* // prints: '1\n2\n3'
*/
function JoinStream( options ) {
var opts;
var err;
if ( !( this instanceof JoinStream ) ) {
if ( arguments.length ) {
return new JoinStream( options );
}
return new JoinStream();
}
opts = copy( DEFAULTS );
if ( arguments.length ) {
err = validate( opts, options );
if ( err ) {
throw err;
}
}
// The stream's writable state should always be in object mode to prevent incoming data from being buffered (concatenated) and thus lose separation...
opts.writableObjectMode = true;
// The stream converts each chunk into a string so no need to encode strings written to the join stream as Buffer objects:
opts.decodeStrings = false;
// Make the stream a Transform stream:
debug( 'Creating a transform stream configured with the following options: %s.', JSON.stringify( opts ) );
Transform.call( this, opts );
// Destruction state:
setNonEnumerable( this, '_destroyed', false );
// Cache the encoding:
setNonEnumerableReadOnly( this, '_encoding', ( opts.encoding === null ) ? 'utf8' : opts.encoding );
// Cache the separator:
if ( this._encoding !== 'utf8' ) {
opts.sep = string2buffer( opts.sep, this._encoding );
}
setNonEnumerableReadOnly( this, '_sep', opts.sep );
// Flag indicating if the stream has received streamed data:
setNonEnumerable( this, '_init', false );
// Chunk counter:
setNonEnumerable( this, '_idx', -1 );
return this;
}
/*
* Inherit from the `Transform` prototype.
*/
inherit( JoinStream, Transform );
/**
* Implements the `_transform` method.
*
* @private
* @name _transform
* @memberof JoinStream.prototype
* @type {Function}
* @param {(Buffer|string)} chunk - streamed chunk
* @param {string} encoding - Buffer encoding
* @param {Callback} clbk - callback to invoke after transforming the streamed chunk
*/
setNonEnumerableReadOnly( JoinStream.prototype, '_transform', transform );
/**
* Implements the `_flush` method.
*
* @private
* @name _flush
* @memberof JoinStream.prototype
* @type {Function}
* @param {Callback} clbk - callback to invoke after performing flush tasks
*/
setNonEnumerableReadOnly( JoinStream.prototype, '_flush', flush );
/**
* Gracefully destroys a stream, providing backward compatibility.
*
* @name destroy
* @memberof JoinStream.prototype
* @type {Function}
* @param {Object} [error] - optional error message
* @returns {JoinStream} Stream instance
*/
setNonEnumerableReadOnly( JoinStream.prototype, 'destroy', destroy );
// EXPORTS //
module.exports = JoinStream;