@stdlib/streams/node/transform/lib/validate.js

Streams.

/**
* @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 isObject = require( '@stdlib/assert/is-plain-object' );
var hasOwnProp = require( '@stdlib/assert/has-own-property' );
var isFunction = require( '@stdlib/assert/is-function' );
var isBoolean = require( '@stdlib/assert/is-boolean' ).isPrimitive;
var isNonNegative = require( '@stdlib/assert/is-nonnegative-number' ).isPrimitive;
var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
var format = require( '@stdlib/string/format' );


// MAIN //

/**
* Validates function options.
*
* @private
* @param {Object} opts - destination object
* @param {Options} options - function options
* @param {Function} [options.transform] - callback to invoke upon receiving a new chunk
* @param {Function} [options.flush] - callback to invoke after receiving all chunks and prior to the stream closing
* @param {boolean} [options.objectMode] - specifies whether a stream should operate in object mode
* @param {(string|null)} [options.encoding] - 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] - specifies whether the stream should remain open even if one side ends
* @param {boolean} [options.decodeStrings] - specifies whether to decode `strings` into `Buffer` objects when writing
* @returns {(Error|null)} null or an error object
*/
function validate( opts, options ) {
	if ( !isObject( options ) ) {
		return new TypeError( format( 'invalid argument. Options argument must be an object. Value: `%s`.', options ) );
	}
	if ( hasOwnProp( options, 'transform' ) ) {
		opts.transform = options.transform;
		if ( !isFunction( opts.transform ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a function. Option: `%s`.', 'transform', opts.transform ) );
		}
	}
	if ( hasOwnProp( options, 'flush' ) ) {
		opts.flush = options.flush;
		if ( !isFunction( opts.flush ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a function. Option: `%s`.', 'flush', opts.flush ) );
		}
	}
	if ( hasOwnProp( options, 'objectMode' ) ) {
		opts.objectMode = options.objectMode;
		if ( !isBoolean( opts.objectMode ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a boolean. Option: `%s`.', 'objectMode', opts.objectMode ) );
		}
	}
	if ( hasOwnProp( options, 'encoding' ) ) {
		opts.encoding = options.encoding;
		if ( !isString( opts.encoding ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a string. Option: `%s`.', 'encoding', opts.encoding ) );
		}
	}
	if ( hasOwnProp( options, 'allowHalfOpen' ) ) {
		opts.allowHalfOpen = options.allowHalfOpen;
		if ( !isBoolean( opts.allowHalfOpen ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a boolean. Option: `%s`.', 'allowHalfOpen', opts.allowHalfOpen ) );
		}
	}
	if ( hasOwnProp( options, 'highWaterMark' ) ) {
		opts.highWaterMark = options.highWaterMark;
		if ( !isNonNegative( opts.highWaterMark ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a nonnegative number. Option: `%s`.', 'highWaterMark', opts.highWaterMark ) );
		}
	}
	if ( hasOwnProp( options, 'decodeStrings' ) ) {
		opts.decodeStrings = options.decodeStrings;
		if ( !isBoolean( opts.decodeStrings ) ) {
			return new TypeError( format( 'invalid option. `%s` option must be a boolean. Option: `%s`.', 'decodeStrings', opts.decodeStrings ) );
		}
	}
	return null;
}


// EXPORTS //

module.exports = validate;