1..4 Size leaves, or null to decline (the caller routes the declaration to custom_css). * It never touches the registry, context, or PropTypes; the caller maps the result onto its own keys. * * Tokenizing is paren-aware so function values such as calc(100% / 4) survive as one token (and are * parsed as a Size leaf). This also makes the elliptical border-radius form (a "/" separator) decline * for free: a bare "/" is an unparsable token, and "a / b" exceeds four tokens. * * - 1 token -> [ 'single' => ] (the union's Size member) * - 2-4 tokens -> [ 'sides' => [ s0, s1, s2, s3 ] ] (expanded via the CSS box rule) * - 0 / >4 tokens, or any unparsable token -> null */ class Box_Shorthand_Parser { const MAX_SIDES = 4; /** * @return array{single: array}|array{sides: array}|null */ public static function parse( string $value ): ?array { $tokens = Css_Token_Splitter::split_by_whitespace( trim( $value ) ); $count = count( $tokens ); if ( $count < 1 || $count > self::MAX_SIDES ) { return null; } $sizes = []; foreach ( $tokens as $token ) { $parsed = Size_Value_Parser::parse( $token ); if ( null === $parsed ) { return null; } $sizes[] = $parsed; } if ( 1 === $count ) { return [ 'single' => $sizes[0] ]; } return [ 'sides' => self::expand_box( $sizes ) ]; } /** * Expand 2..4 values onto four sides via the CSS box rule. The result is positional and the same * for every box shorthand; the caller assigns the four slots to its own keys. * * @param array $sizes 2..4 parsed Size leaves. * @return array{0: array, 1: array, 2: array, 3: array} */ private static function expand_box( array $sizes ): array { switch ( count( $sizes ) ) { case 2: return [ $sizes[0], $sizes[1], $sizes[0], $sizes[1] ]; case 3: return [ $sizes[0], $sizes[1], $sizes[2], $sizes[1] ]; default: return [ $sizes[0], $sizes[1], $sizes[2], $sizes[3] ]; } } }