> ## Documentation Index
> Fetch the complete documentation index at: https://phiki.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Caching

Syntax highlighting can be a resource-intensive operation, especially for large code snippets or when processing many snippets in a short period.

To improve performance, Phiki includes a built-in caching mechanism built around the `psr/simple-cache` interface.

## Enabling caching

Enabling caching is as simple as providing a cache implementation to the `Phiki::cache()` method.

```php theme={null}
class SimpleCache implements \Psr\SimpleCache\CacheInterface
{
    // ...
}

$phiki = (new Phiki)
    ->cache(new SimpleCache);
```

This will enable caching for all subsequent calls to `codeToHtml()`. The cache will store the generated HTML for each unique combination of code, grammar, theme(s), gutter setting and `Transformer` class.

## Cache invalidation

Phiki does not include any built-in cache invalidation mechanism apart from a change in the cache key.

If you need to invalidate the cache for any reason, you must do so using the methods provided by your chosen cache implementation.

## Caching individual snippets

If you don't want to cache all syntax highlighted code, you can also cache individual `codeToHtml()` calls by passing a cache implementation to the `PendingHtmlOutput::cache()` method.

```php theme={null}
$html = (new Phiki)
    ->codeToHtml("<?php echo ...", Grammar::Php, Theme::GithubLight)
    ->cache(new SimpleCache)
    ->toString();
```