https://github.com/takuya/php-generators-into-array-access
php yield generator as ArrayAccess.
https://github.com/takuya/php-generators-into-array-access
Last synced: 8 months ago
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php yield generator as ArrayAccess.
- Host: GitHub
- URL: https://github.com/takuya/php-generators-into-array-access
- Owner: takuya
- License: gpl-3.0
- Created: 2023-02-26T09:01:51.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2023-02-28T16:34:53.000Z (over 3 years ago)
- Last Synced: 2025-03-11T23:14:52.329Z (over 1 year ago)
- Language: PHP
- Size: 43.9 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# php / GeneratorArrayAccess
Make generator(yield) into ArrayAccess.
## Example
```php
'x'
$iter[1]; #=> 'y'
$iter[2]; #=> 'z'
```
## Why use.
Generator can foreach itself. but, cannot access as Array. This characteristic is against developers's intention. Like this.
### Generator cannot be a array.
```php
class MyClass{
public function elements(){
foreach ($this->paths[] as $path){
yield get_something($path);
}
}
}
$node = new MyClass();
// Generator can Access foreach
foreach ($node->elements() as $item) {
// something.
}
// but Cannot access as Array
$first = $node->elements()[0]; //=> Error
```
### CachingIterator is not enough
Using `\CachingIterator` is a common way, but make a problem
#### \CachingIterator cannot be a array.
This behaviour is very confusing.
```php
$node = new MyClass();
$elements = new CachingIterator($node->elements())
// CachingIterator cannot access Directory, before cached.
$first = $elements[1]; //=> BadMethodCallException
// after caching, CachingIterator can access as Array.
foreach ($elements as $e){;;}
$first = $elements[1]; //=> not null.
```
With FullCache option, cached at initializing.
```php
$node = new MyClass();
$elements = new \CachingIterator(
$node->elements(),
\CachingIterator::FULL_CACHE
);// <= All Cached on constructor.
```
If generator is API call, It can spend a lot of time, caching time inevitable.
CachingIterator is useless. Everyone uses `iterator_to_array()` instead.
`iterator_to_array()`function has same problem ( load all, mess up Generator concept, get data when using ).
### Dynamically get, make Unnecessary api call avoidable.
To solve that problem ,GeneratorArrayAccess cache dynamically.
```php
$node = new MyClass();
$iter = new GeneratorArrayAccess($node->elements());
$iter[1]; //=> make cache $iter[0],$iter[1];
$iter[9]; //=> make cache $iter[0]...$iter[9]
```
Cache is able to reuse.
```php
$node = new MyClass();
$iter = new GeneratorArrayAccess($node->elements());
// first access
foreach($iter as $e){;;}
// cache access with rewind.
foreach($iter as $e){;;}
```
## When use this.
Reduce WebAPI Call. without re-arrange code.
Current exists code.
```php
function my_list_items(){
foreach( $api->call('list_item') as $id){
$list[]=$api->call('get_item', $id);
}
return $list;
}
$items = $my_list_items();
$item = $items[0];
```
Use Generator.
```php
function my_list_items(){
foreach( $api->call('list_item') as $id){
$item = $api->call('get_item', $id);
yield $item;
}
}
$items = $my_list_items();
$item = $items[0];//<= No Code changed. Becomes ERORR!.
```
Use GeneratorArrayAccess
```php
function my_list_items(){
return new GeneratorArrayAccess((function(){
foreach( $api->call('list_item') as $id){
$item = $api->call('get_item', $id);
yield $item;
}
})());
}
$items = $my_list_items();
$item = $items[0];//<= No Code changed. **No Error**.
```
This class supports to make use of Generator(yield), Less code changed.
### Limitations.
Infinite generator will be no response.
```php
$generator = (function(){
while(true){ yield 'a';}
})();
$iter = new GeneratorArrayAccess($generator);
sizeof($iter);//=> infinite loop
```
## Installation
from github
```shell
repository='php-generators-into-array-access'
composer config repositories.$repository \
vcs https://github.com/takuya/$repository
composer require takuya/$repository:master
composer install
```
from composer
```shell
composer require takuya/php-genetator-array-access
```