time-to-botec/js/node_modules/@stdlib/array/to-view-iterator/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

218 lines
5.2 KiB
JavaScript

/**
* @license Apache-2.0
*
* Copyright (c) 2019 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 setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
var isFunction = require( '@stdlib/assert/is-function' );
var isCollection = require( '@stdlib/assert/is-collection' );
var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
var iteratorSymbol = require( '@stdlib/symbol/iterator' );
// MAIN //
/**
* Returns an iterator which iterates over each element in an array-like object view.
*
* @param {Collection} src - input value
* @param {integer} [begin=0] - starting index (inclusive)
* @param {integer} [end=src.length] - ending index (non-inclusive)
* @param {Function} [mapFcn] - function to invoke for each iterated value
* @param {*} [thisArg] - execution context
* @throws {TypeError} first argument must be an array-like object
* @throws {TypeError} second argument must be either an integer (starting index) or a function
* @throws {TypeError} third argument must be either an integer (ending index) or a function
* @throws {TypeError} fourth argument must be a function
* @returns {Iterator} iterator
*
* @example
* var iter = arrayview2iterator( [ 1, 2, 3, 4 ], 1, 3 );
*
* var v = iter.next().value;
* // returns 2
*
* v = iter.next().value;
* // returns 3
*
* var bool = iter.next().done;
* // returns true
*/
function arrayview2iterator( src ) {
var thisArg;
var begin;
var nargs;
var iter;
var FLG;
var fcn;
var end;
var i;
if ( !isCollection( src ) ) {
throw new TypeError( 'invalid argument. First argument must be an array-like object. Value: `' + src + '`.' );
}
nargs = arguments.length;
if ( nargs === 1 ) {
begin = 0;
end = src.length;
} else if ( nargs === 2 ) {
if ( isFunction( arguments[ 1 ] ) ) {
begin = 0;
fcn = arguments[ 1 ];
} else {
begin = arguments[ 1 ];
}
end = src.length;
} else if ( nargs === 3 ) {
if ( isFunction( arguments[ 1 ] ) ) {
begin = 0;
end = src.length;
fcn = arguments[ 1 ];
thisArg = arguments[ 2 ];
} else if ( isFunction( arguments[ 2 ] ) ) {
begin = arguments[ 1 ];
end = src.length;
fcn = arguments[ 2 ];
} else {
begin = arguments[ 1 ];
end = arguments[ 2 ];
}
} else { // nargs >= 4
begin = arguments[ 1 ];
end = arguments[ 2 ];
fcn = arguments[ 3 ];
if ( !isFunction( fcn ) ) {
throw new TypeError( 'invalid argument. Fourth argument must be a function. Value: `' + fcn + '`.' );
}
thisArg = arguments[ 4 ];
}
if ( !isInteger( begin ) ) {
throw new TypeError( 'invalid argument. Second argument must be either an integer (starting index) or a callback function. Value: `' + begin + '`.' );
}
if ( !isInteger( end ) ) {
throw new TypeError( 'invalid argument. Third argument must be either an integer (ending index) or a callback function. Value: `' + end + '`.' );
}
if ( end < 0 ) {
end = src.length + end;
if ( end < 0 ) {
end = 0;
}
} else if ( end > src.length ) {
end = src.length;
}
if ( begin < 0 ) {
begin = src.length + begin;
if ( begin < 0 ) {
begin = 0;
}
}
i = begin - 1;
// Create an iterator protocol-compliant object:
iter = {};
if ( fcn ) {
setReadOnly( iter, 'next', next1 );
} else {
setReadOnly( iter, 'next', next2 );
}
setReadOnly( iter, 'return', finish );
// If an environment supports `Symbol.iterator`, make the iterator iterable:
if ( iteratorSymbol ) {
setReadOnly( iter, iteratorSymbol, factory );
}
return iter;
/**
* Returns an iterator protocol-compliant object containing the next iterated value.
*
* @private
* @returns {Object} iterator protocol-compliant object
*/
function next1() {
i += 1;
if ( FLG || i >= end ) {
return {
'done': true
};
}
return {
'value': fcn.call( thisArg, src[ i ], i, i-begin, src ),
'done': false
};
}
/**
* Returns an iterator protocol-compliant object containing the next iterated value.
*
* @private
* @returns {Object} iterator protocol-compliant object
*/
function next2() {
i += 1;
if ( FLG || i >= end ) {
return {
'done': true
};
}
return {
'value': src[ i ],
'done': false
};
}
/**
* Finishes an iterator.
*
* @private
* @param {*} [value] - value to return
* @returns {Object} iterator protocol-compliant object
*/
function finish( value ) {
FLG = true;
if ( arguments.length ) {
return {
'value': value,
'done': true
};
}
return {
'done': true
};
}
/**
* Returns a new iterator.
*
* @private
* @returns {Iterator} iterator
*/
function factory() {
if ( fcn ) {
return arrayview2iterator( src, begin, end, fcn, thisArg );
}
return arrayview2iterator( src, begin, end );
}
}
// EXPORTS //
module.exports = arrayview2iterator;