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feat: add iter/until-each
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PR-URL: stdlib-js#1389
Closes: stdlib-js#809 

Co-authored-by: stdlib-bot <82920195+stdlib-bot@users.noreply.github.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>
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JawHawk and stdlib-bot authored Feb 27, 2024
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233 changes: 233 additions & 0 deletions lib/node_modules/@stdlib/iter/until-each/README.md
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<!--
@license Apache-2.0
Copyright (c) 2024 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.
-->

# iterUntilEach

> Create an iterator which, while a test condition is false, invokes a function for each iterated value before returning the iterated value.
<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var iterUntilEach = require( '@stdlib/iter/until-each' );
```

#### iterUntilEach( iterator, predicate, fcn\[, thisArg] )

Returns an iterator which invokes a function for each iterated value **before** returning the iterated value until either a `predicate` function returns `true` or the iterator has iterated over all values.

```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );

function predicate( v ) {
return v > 2;
}

function assert( v ) {
if ( v !== v ) {
throw new Error( 'should not be NaN' );
}
}

var it = iterUntilEach( array2iterator( [ 1, 2, 3, 4 ] ), predicate, assert );
// returns {}

var r = it.next().value;
// returns 1

r = it.next().value;
// returns 2

r = it.next().value;
// undefined

// ...
```

The returned iterator protocol-compliant object has the following properties:

- **next**: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a boolean value indicating whether the iterator is finished.
- **return**: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

Both the `predicate` function and the function to invoke for each iterated value are provided two arguments:

- **value**: iterated value
- **index**: iteration index (zero-based)

```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );

function predicate( v ) {
return v > 2;
}

function assert( v, i ) {
if ( i > 1 ) {
throw new Error( 'unexpected error' );
}
}

var it = iterUntilEach( array2iterator( [ 1, 2, 3, 4 ] ), predicate, assert );
// returns <Object>

var r = it.next().value;
// returns 1

r = it.next().value;
// returns 2

r = it.next().value;
// undefined

// ...
```

To set the execution context for `fcn`, provide a `thisArg`.

<!-- eslint-disable no-invalid-this -->

```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );

function assert( v ) {
this.count += 1;
if ( v !== v ) {
throw new Error( 'should not be NaN' );
}
}

function predicate( v ) {
return v > 2;
}

var ctx = {
'count': 0
};

var it = iterUntilEach( array2iterator( [ 1, 2, 3 ] ), predicate, assert, ctx );
// returns <Object>

var r = it.next().value;
// returns 1

r = it.next().value;
// returns 2

var count = ctx.count;
// returns 2
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

- If an environment supports `Symbol.iterator` **and** a provided iterator is iterable, the returned iterator is iterable.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var randu = require( '@stdlib/random/iter/randu' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var iterUntilEach = require( '@stdlib/iter/until-each' );

function assert( v ) {
if ( isnan( v ) ) {
throw new Error( 'should not be NaN' );
}
}

function predicate( v ) {
return v <= 0.75;
}

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234,
'iter': 10
});

// Create an iterator which validates generated numbers:
var it = iterUntilEach( rand, predicate, assert );

// Perform manual iteration...
var r;
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}
```

</section>

<!-- /.examples -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

</section>

<!-- /.links -->
97 changes: 97 additions & 0 deletions lib/node_modules/@stdlib/iter/until-each/benchmark/benchmark.js
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/**
* @license Apache-2.0
*
* Copyright (c) 2024 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 bench = require( '@stdlib/bench' );
var randu = require( '@stdlib/random/iter/randu' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var isIteratorLike = require( '@stdlib/assert/is-iterator-like' );
var pkg = require( './../package.json' ).name;
var iterator = require( './../lib' );


// MAIN //

bench( pkg, function benchmark( b ) {
var rand;
var iter;
var i;

rand = randu();

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
iter = iterator( rand, predicate, fcn );
if ( typeof iter !== 'object' ) {
b.fail( 'should return an object' );
}
}
b.toc();
if ( !isIteratorLike( iter ) ) {
b.fail( 'should return an iterator protocol-compliant object' );
}
b.pass( 'benchmark finished' );
b.end();

function fcn( v ) {
if ( isnan( v ) ) {
b.fail( 'should not return NaN' );
}
}

function predicate( v ) {
return ( v < 0.5 );
}
});

bench( pkg+'::iteration', function benchmark( b ) {
var rand;
var iter;
var z;
var i;

rand = randu();
iter = iterator( rand, predicate, fcn );

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
z = iter.next().value;
if ( isnan( z ) ) {
b.fail( 'should not return NaN' );
}
}
b.toc();
if ( isnan( z ) ) {
b.fail( 'should not return NaN' );
}
b.pass( 'benchmark finished' );
b.end();

function fcn( v ) {
if ( isnan( v ) ) {
b.fail( 'should not return NaN' );
}
}

function predicate( v ) {
return ( v < 0.5 );
}
});
54 changes: 54 additions & 0 deletions lib/node_modules/@stdlib/iter/until-each/docs/repl.txt
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{{alias}}( iterator, predicate, fcn[, thisArg] )
Returns an iterator which invokes a function for each iterated value before
returning the iterated value until either a predicate function returns true
or the iterator has iterated over all values.

When invoked, both input functions are provided two arguments:

- value: iterated value
- index: iteration index (zero-based)

If an environment supports Symbol.iterator, the returned iterator is
iterable.

Parameters
----------
iterator: Object
Input iterator.

predicate: Function
Function which indicates whether to continue iterating.

fcn: Function
Function to invoke for each iterated value.

thisArg: any (optional)
Execution context.

Returns
-------
iterator: Object
Iterator.

iterator.next(): Function
Returns an iterator protocol-compliant object containing the next
iterated value (if one exists) and a boolean flag indicating whether the
iterator is finished.

iterator.return( [value] ): Function
Finishes an iterator and returns a provided value.

Examples
--------
> function predicate( v ) { return v !== v };
> function f( v ) { if ( v !== v ) { throw new Error( 'beep' ); } };
> var it = {{alias}}( {{alias:@stdlib/random/iter/randu}}(), predicate, f );
> var r = it.next().value
<number>
> r = it.next().value
<number>

See Also
--------

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