CSS Rule Saver works in much the same way that a browser might. It compares a list of CSS rules (e.g. .foo { color: white; } ) from a CSS file against an HTML file using the CSS selector (e.g. .foo ) to see which rules apply and should be saved. This might be useful if you have a large Sass-generated CSS file or framework but only need the sub-set of styles that may affect a small piece of mark-up.
This is not a very robust solution. It appears to work well on the examples I have but your mileage may vary. Pseudo-classes are ignored and instead the base selector for a pseudo-class is compared. I may also be missing selector or at-rule methods. Feel free to drop an issue if you notice this.
At the moment, CSS Rule Saver does not overwrite values for specific properties. Instead, it stacks declaration blocks for a specific selector. It works but it's a little verbose. I plan on fixing that.
CSS Rule Saver has not had any optimizations for speed or memory usage.
A simple example shows how CSS Rule Saver can be used to compare the rules from one CSS file against one HTML file.
require "css-rule-saver.php";
// initialize the class
$crs = new cssRuleSaver;
// load the CSS & HTML files to compare
$crs->loadCSS("example.css");
$crs->loadHTML("example.html");
// save only the CSS rules that affect the given piece of mark-up
$results = $crs->saveRules();
print $results;The loadHTML() and saveRules() methods can be called multiple times even while loading only one CSS file via the loadCSS() method. For example, the following would compare the rules in example.css against each HTML document and print the results for each.
require "css-rule-saver.php";
// initialize the class
$crs = new cssRuleSaver;
// load the CSS file to compare
$crs->loadCSS("example.css");
// loop over a list of files & print out the matching rules
$files = array("1.html","2.html","3.html");
foreach ($files as $file) {
$crs->loadHTML($file);
$results = $crs->saveRules();
print "Results for ".$file.":\n";
print $results;
print "\n\n";
}This library relies on php-selector developed by TJ Holowaychuk and improved by @darhazer and @kafene.