--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/style-engine/class-wp-style-engine-css-declarations.php	Fri Sep 05 18:40:08 2025 +0200
@@ -0,0 +1,187 @@
+<?php
+/**
+ * Style Engine: WP_Style_Engine_CSS_Declarations class
+ *
+ * @package WordPress
+ * @subpackage StyleEngine
+ * @since 6.1.0
+ */
+
+/**
+ * Core class used for style engine CSS declarations.
+ *
+ * Holds, sanitizes, processes, and prints CSS declarations for the style engine.
+ *
+ * @since 6.1.0
+ */
+#[AllowDynamicProperties]
+class WP_Style_Engine_CSS_Declarations {
+
+	/**
+	 * An array of CSS declarations (property => value pairs).
+	 *
+	 * @since 6.1.0
+	 *
+	 * @var string[]
+	 */
+	protected $declarations = array();
+
+	/**
+	 * Constructor for this object.
+	 *
+	 * If a `$declarations` array is passed, it will be used to populate
+	 * the initial `$declarations` prop of the object by calling add_declarations().
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string[] $declarations Optional. An associative array of CSS definitions,
+	 *                               e.g. `array( "$property" => "$value", "$property" => "$value" )`.
+	 *                               Default empty array.
+	 */
+	public function __construct( $declarations = array() ) {
+		$this->add_declarations( $declarations );
+	}
+
+	/**
+	 * Adds a single declaration.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $property The CSS property.
+	 * @param string $value    The CSS value.
+	 * @return WP_Style_Engine_CSS_Declarations Returns the object to allow chaining methods.
+	 */
+	public function add_declaration( $property, $value ) {
+		// Sanitizes the property.
+		$property = $this->sanitize_property( $property );
+		// Bails early if the property is empty.
+		if ( empty( $property ) ) {
+			return $this;
+		}
+
+		// Trims the value. If empty, bail early.
+		$value = trim( $value );
+		if ( '' === $value ) {
+			return $this;
+		}
+
+		// Adds the declaration property/value pair.
+		$this->declarations[ $property ] = $value;
+
+		return $this;
+	}
+
+	/**
+	 * Removes a single declaration.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $property The CSS property.
+	 * @return WP_Style_Engine_CSS_Declarations Returns the object to allow chaining methods.
+	 */
+	public function remove_declaration( $property ) {
+		unset( $this->declarations[ $property ] );
+		return $this;
+	}
+
+	/**
+	 * Adds multiple declarations.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string[] $declarations An array of declarations.
+	 * @return WP_Style_Engine_CSS_Declarations Returns the object to allow chaining methods.
+	 */
+	public function add_declarations( $declarations ) {
+		foreach ( $declarations as $property => $value ) {
+			$this->add_declaration( $property, $value );
+		}
+		return $this;
+	}
+
+	/**
+	 * Removes multiple declarations.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string[] $properties Optional. An array of properties. Default empty array.
+	 * @return WP_Style_Engine_CSS_Declarations Returns the object to allow chaining methods.
+	 */
+	public function remove_declarations( $properties = array() ) {
+		foreach ( $properties as $property ) {
+			$this->remove_declaration( $property );
+		}
+		return $this;
+	}
+
+	/**
+	 * Gets the declarations array.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @return string[] The declarations array.
+	 */
+	public function get_declarations() {
+		return $this->declarations;
+	}
+
+	/**
+	 * Filters a CSS property + value pair.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $property The CSS property.
+	 * @param string $value    The value to be filtered.
+	 * @param string $spacer   Optional. The spacer between the colon and the value.
+	 *                         Default empty string.
+	 * @return string The filtered declaration or an empty string.
+	 */
+	protected static function filter_declaration( $property, $value, $spacer = '' ) {
+		$filtered_value = wp_strip_all_tags( $value, true );
+		if ( '' !== $filtered_value ) {
+			return safecss_filter_attr( "{$property}:{$spacer}{$filtered_value}" );
+		}
+		return '';
+	}
+
+	/**
+	 * Filters and compiles the CSS declarations.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param bool $should_prettify Optional. Whether to add spacing, new lines and indents.
+	 *                              Default false.
+	 * @param int  $indent_count    Optional. The number of tab indents to apply to the rule.
+	 *                              Applies if `prettify` is `true`. Default 0.
+	 * @return string The CSS declarations.
+	 */
+	public function get_declarations_string( $should_prettify = false, $indent_count = 0 ) {
+		$declarations_array  = $this->get_declarations();
+		$declarations_output = '';
+		$indent              = $should_prettify ? str_repeat( "\t", $indent_count ) : '';
+		$suffix              = $should_prettify ? ' ' : '';
+		$suffix              = $should_prettify && $indent_count > 0 ? "\n" : $suffix;
+		$spacer              = $should_prettify ? ' ' : '';
+
+		foreach ( $declarations_array as $property => $value ) {
+			$filtered_declaration = static::filter_declaration( $property, $value, $spacer );
+			if ( $filtered_declaration ) {
+				$declarations_output .= "{$indent}{$filtered_declaration};$suffix";
+			}
+		}
+
+		return rtrim( $declarations_output );
+	}
+
+	/**
+	 * Sanitizes property names.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $property The CSS property.
+	 * @return string The sanitized property name.
+	 */
+	protected function sanitize_property( $property ) {
+		return sanitize_key( $property );
+	}
+}