Box_Shadow_Prop_Type (array of Shadow_Prop_Type). * * Per-layer CSS grammar: * = ? && [{2,4}] && inset? * * Token classification (paren-aware so rgb(255 0 0) stays one token): * - `inset` -> position keyword * - parses as Size -> length token * - anything else -> color (at most one per layer) * * Length mapping by count: * 2 -> hOffset, vOffset * 3 -> hOffset, vOffset, blur * 4 -> hOffset, vOffset, blur, spread * Any other count, multiple colors, or unrecognised tokens decline the entire declaration to custom_css. * * Defaults: * - missing color -> `currentColor` (CSS spec default) * - missing blur/spread -> 0 px * * Special values: * - `none` -> empty Box_Shadow array (clears the prop). */ class Box_Shadow_Property_Converter extends Property_Converter_Base { const INSET_KEYWORD = 'inset'; const DEFAULT_COLOR = 'currentColor'; const ZERO_SIZE = [ 'size' => 0, 'unit' => 'px', ]; protected function get_supported_properties(): array { return [ 'box-shadow' ]; } protected function do_convert( Conversion_Context $context, array $rule ): bool { $value = trim( $rule['value'] ); if ( '' === $value ) { return false; } if ( 'none' === strtolower( $value ) ) { $context->set_prop( 'box-shadow', Box_Shadow_Prop_Type::generate( [] ) ); return true; } $layers = Css_Token_Splitter::split_by_comma( $value ); $shadows = []; foreach ( $layers as $layer ) { $shadow = $this->parse_layer( trim( $layer ) ); if ( null === $shadow ) { return false; } $shadows[] = $shadow; } $context->set_prop( 'box-shadow', Box_Shadow_Prop_Type::generate( $shadows ) ); return true; } private function parse_layer( string $layer ): ?array { $tokens = Css_Token_Splitter::split_by_whitespace( $layer ); if ( empty( $tokens ) ) { return null; } $lengths = []; $color = null; $is_inset = false; foreach ( $tokens as $token ) { if ( self::INSET_KEYWORD === strtolower( $token ) ) { if ( $is_inset ) { return null; } $is_inset = true; continue; } $size = Size_Value_Parser::parse( $token ); if ( null !== $size ) { $lengths[] = $size; continue; } if ( null !== $color ) { return null; } $color = $token; } $length_count = count( $lengths ); if ( $length_count < 2 || $length_count > 4 ) { return null; } return Shadow_Prop_Type::generate( $this->build_shadow_fields( $lengths, $color, $is_inset ) ); } private function build_shadow_fields( array $lengths, ?string $color, bool $is_inset ): array { $fields = [ 'hOffset' => Size_Prop_Type::generate( $lengths[0] ), 'vOffset' => Size_Prop_Type::generate( $lengths[1] ), 'blur' => Size_Prop_Type::generate( $lengths[2] ?? self::ZERO_SIZE ), 'spread' => Size_Prop_Type::generate( $lengths[3] ?? self::ZERO_SIZE ), 'color' => Color_Prop_Type::generate( $color ?? self::DEFAULT_COLOR ), ]; if ( $is_inset ) { $fields['position'] = String_Prop_Type::generate( self::INSET_KEYWORD ); } return $fields; } }