block_core_gallery_get_column_gap_value( string|array|null $gap, string $fallback_gap ): string

64function block_core_gallery_get_column_gap_value( $gap, $fallback_gap ) {65	if ( is_array( $gap ) ) {66		$gap = $gap['left'] ?? $fallback_gap;67	}68 69	// Make sure $gap is a string to avoid PHP 8.1 deprecation error in preg_match() when the value is null.70	$gap = is_string( $gap ) ? $gap : '';71 72	// Skip if gap value contains unsupported characters.73	// Regex for CSS value borrowed from `safecss_filter_attr`, and used here74	// because we only want to match against the value, not the CSS attribute.75	$gap = $gap && preg_match( '%[\\\(&=}]|/\*%', $gap ) ? null : $gap;76 77	// Get spacing CSS variable from preset value if provided.78	if ( is_string( $gap ) && str_contains( $gap, 'var:preset|spacing|' ) ) {79		$index_to_splice = strrpos( $gap, '|' ) + 1;80		$slug            = _wp_to_kebab_case( substr( $gap, $index_to_splice ) );81		$gap             = "var(--wp--preset--spacing--$slug)";82	}83 84	$gap_column = ( null !== $gap && '' !== $gap ) ? $gap : $fallback_gap;85 86	// The unstable gallery gap calculation requires a real value (such as `0px`) and not `0`.87	return '0' === $gap_column ? '0px' : $gap_column;88}