README

zest.php is a fast, lightweight, extensible CSS selector engine for PHP.

Zest was designed to be very concise while still supporting CSS3/CSS4 selectors and remaining fast.

This is a port to PHP of the zest.js selector library. Since that project hasn't been updated in a while, bugfixes have been taken from the copy of zest included in the domino DOM library.

Usage

use Wikimedia\Zest\Zest;

$els = Zest::find('section! > div[title="hello" i] > :local-link /href/ h1', $doc);

Install

This package is available on Packagist:

$ composer require wikimedia/zest-css

API

Zest::find( string $selector, DOMNode $context ): array

This is equivalent to the standard DOM method ParentNode#querySelectorAll().

Zest::matches( DOMNode $element, string $selector ): bool

This is equivalent to the standard DOM method Element#matches().

Since the PHP implementations of DOMDocument::getElementById and DOMDocument#getElementsByTagName have some performance and spec-compliance issues, Zest also exports useful performant and correct versions of these:

Zest::getElementsById( DOMNode $contextNode, string $id ): array

This is equivalent to the standard DOM method Document#getElementById() (although you can use any context node, not just the top-level document).

Zest::getElementsByTagName( DOMNode $contextNode, string $tagName ): DOMNodeList

This is equivalent to the standard DOM method Element#getElementsByTagName().

Extension

It is possible to add your own selectors, operators, or combinators. These are added to an instance of ZestInst, so they don't affect other instances of Zest or the static Zest::find/Zest::matches methods. The ZestInst class has non-static versions of all the static methods available on Zest.

Adding a simple selector

Adding simple selectors is fairly straight forward. Only the addition of pseudo classes and attribute operators is possible. (Adding your own "style" of selector would require changes to the core logic.)

Here is an example of a custom :name selector which will match for an element's name attribute: e.g. h1:name(foo). Effectively an alias for h1[name=foo].

use Wikimedia\Zest\ZestInst;

$z = new ZestInst;
$z->addSelector1( ':name', function( string $param ):callable {
  return function ( DOMNode $el ) use ( $param ):bool {
    if ($el->getAttribute('name') === $param) return true;
    return false;
  };
} );

// Use it!
$z->find( 'h1:name(foo)', $document );

NOTE: if your pseudo-class does not take a parameter, use addSelector0.

Adding an attribute operator

$z = new ZestInst;
// `$attr` is the attribute
// `$val` is the value to match
$z->addOperator( '!=', function( string $attr, string $val ):bool {
  return $attr !== $val;
} );

// Use it!
$z->find( 'h1[name != "foo"]', $document );

Adding a combinator

Adding a combinator is a bit trickier. It may seem confusing at first because the logic is upside-down. Zest interprets selectors from right to left.

Here is an example how a parent combinator could be implemented:

$z = new ZestInst;
$z->addCombinator( '<', function( callable $test ): callable {
  return function( DOMNode $el ) use ( $test ): ?DOMNode {
    // `$el` is the current element
    $el = $el->firstChild;
    while ($el) {
      // return the relevant element
      // if it passed the test
      if ($el->nodeType === 1 && call_user_func($test, $el)) {
        return $el;
      }
      $el = $el->nextSibling;
    }
    return null;
  };
} );

// Use it!
$z->find( 'h1 < section', $document );

The $test function tests whatever simple selectors it needs to look for, but it isn't important what it does. The most important part is that you return the relevant element once it's found.

Tests

$ composer test

License and Credits

The original zest codebase is (c) Copyright 2011-2012, Christopher Jeffrey.

The port to PHP was initially done by C. Scott Ananian and is (c) Copyright 2019 Wikimedia Foundation.

Both the original zest codebase and this port are distributed under the MIT license; see LICENSE for more info.