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

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'
}

Top ↑

Parameters

$tree

(array) (Required) Input tree to process.

$prefix

(string) (Optional) Prefix to prepend to each variable.

Default value: ''

$token

(string) (Optional) Token to use between levels.

Default value: '--'


Top ↑

Return

(array) The flattened tree.


Top ↑

Source

File: wp-includes/class-wp-theme-json.php

	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;
				$result     = array_merge(
					$result,
					static::flatten_tree( $value, $new_prefix, $token )
				);
			} else {
				$result[ $new_key ] = $value;
			}
		}
		return $result;
	}


Top ↑

Changelog

Changelog
Version Description
5.8.0 Introduced.

Top ↑

User Contributed Notes

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