WP_Theme_JSON::merge( WP_Theme_JSON $incoming )

Source

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

public function merge( $incoming ) {
		$incoming_data    = $incoming->get_raw_data();
		$this->theme_json = array_replace_recursive( $this->theme_json, $incoming_data );

		/*
		 * The array_replace_recursive() algorithm merges at the leaf level.
		 * For leaf values that are arrays it will use the numeric indexes for replacement.
		 * In those cases, we want to replace the existing with the incoming value, if it exists.
		 */
		$to_replace   = array();
		$to_replace[] = array( 'spacing', 'units' );
		$to_replace[] = array( 'color', 'duotone' );
		foreach ( self::VALID_ORIGINS as $origin ) {
			$to_replace[] = array( 'color', 'palette', $origin );
			$to_replace[] = array( 'color', 'gradients', $origin );
			$to_replace[] = array( 'typography', 'fontSizes', $origin );
			$to_replace[] = array( 'typography', 'fontFamilies', $origin );
		}

		$nodes = self::get_setting_nodes( $this->theme_json );
		foreach ( $nodes as $metadata ) {
			foreach ( $to_replace as $property_path ) {
				$path = array_merge( $metadata['path'], $property_path );
				$node = _wp_array_get( $incoming_data, $path, null );
				if ( isset( $node ) ) {
					_wp_array_set( $this->theme_json, $path, $node );
				}
			}
		}
	}