WP_Theme_JSON::flatten_tree( array $tree, string $prefix, string $token ): array

Given a tree, it creates a flattened one by merging the keys and binding the leaf values to the new keys.

Description

It also transforms camelCase names into kebab-case and substitutes ‘/’ by ‘-‘.

This is thought to be useful to generate CSS Custom Properties from a tree, although there’s nothing in the implementation of this function that requires that format.

For example, assuming the given prefix is ‘–wp’ and the token is ‘–‘, for this input tree:

{
  'some/property': 'value',
  'nestedProperty': {
    'sub-property': 'value'
  }
}

it’ll return this output:

{
  '--wp--some-property': 'value',
  '--wp--nested-property--sub-property': 'value'
}

Parameters

$treearrayrequired
Input tree to process.
$prefixstringoptional
Prefix to prepend to each variable. Default empty string.
$tokenstringoptional
Token to use between levels. Default '--'.

Return

array The flattened tree.

Source

protected static function flatten_tree( $tree, $prefix = '', $token = '--' ) {
	$result = array();
	foreach ( $tree as $property => $value ) {
		$new_key = $prefix . str_replace(
			'/',
			'-',
			strtolower( _wp_to_kebab_case( $property ) )
		);

		if ( is_array( $value ) ) {
			$new_prefix        = $new_key . $token;
			$flattened_subtree = static::flatten_tree( $value, $new_prefix, $token );
			foreach ( $flattened_subtree as $subtree_key => $subtree_value ) {
				$result[ $subtree_key ] = $subtree_value;
			}
		} else {
			$result[ $new_key ] = $value;
		}
	}
	return $result;
}

Changelog

VersionDescription
5.8.0Introduced.

User Contributed Notes

You must log in before being able to contribute a note or feedback.