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