Editor: Backport Style Engine API functions, classes and tests.

This PR migrates the Style Engine PHP functions, classes and tests into Core for 6.1. It backports the original [WordPress/gutenberg#40260 PR #40260] from Gutenberg repository.

Props ramonopoly, bernhard-reiter, costdev, azaozz, andrewserong, mukesh27, aristath.
See #56467.

Built from https://develop.svn.wordpress.org/trunk@54156

wp-includes/style-engine.php

@@ -0,0 +1,154 @@
+<?php
+/**
+ * Style engine: Public functions
+ *
+ * This file contains a variety of public functions developers can use to interact with
+ * the Style Engine API.
+ *
+ * @package WordPress
+ * @subpackage StyleEngine
+ * @since 6.1.0
+ */
+
+
+/**
+ * Global public interface method to generate styles from a single style object, e.g.,
+ * the value of a block's attributes.style object or the top level styles in theme.json.
+ * See: https://developer.wordpress.org/block-editor/reference-guides/theme-json-reference/theme-json-living/#styles and
+ * https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/
+ *
+ * Example usage:
+ *
+ * $styles = wp_style_engine_get_styles( array( 'color' => array( 'text' => '#cccccc' ) ) );
+ * // Returns `array( 'css' => 'color: #cccccc', 'declarations' => array( 'color' => '#cccccc' ), 'classnames' => 'has-color' )`.
+ *
+ * @access public
+ * @since 6.1.0
+ *
+ * @param array $block_styles The style object.
+ * @param array $options {
+ *     Optional. An array of options. Default empty array.
+ *
+ *     @type string|null $context                    An identifier describing the origin of the style object, e.g., 'block-supports' or 'global-styles'. Default is `null`.
+ *                                                   When set, the style engine will attempt to store the CSS rules, where a selector is also passed.
+ *     @type bool        $convert_vars_to_classnames Whether to skip converting incoming CSS var patterns, e.g., `var:preset|<PRESET_TYPE>|<PRESET_SLUG>`, to var( --wp--preset--* ) values. Default `false`.
+ *     @type string      $selector                   Optional. When a selector is passed, the value of `$css` in the return value will comprise a full CSS rule `$selector { ...$css_declarations }`,
+ *                                                   otherwise, the value will be a concatenated string of CSS declarations.
+ * }
+ *
+ * @return array {
+ *     @type string   $css          A CSS ruleset or declarations block formatted to be placed in an HTML `style` attribute or tag.
+ *     @type string[] $declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
+ *     @type string   $classnames   Classnames separated by a space.
+ * }
+ */
+function wp_style_engine_get_styles( $block_styles, $options = array() ) {
+	$options = wp_parse_args(
+		$options,
+		array(
+			'selector'                   => null,
+			'context'                    => null,
+			'convert_vars_to_classnames' => false,
+		)
+	);
+
+	$parsed_styles = WP_Style_Engine::parse_block_styles( $block_styles, $options );
+
+	// Output.
+	$styles_output = array();
+
+	if ( ! empty( $parsed_styles['declarations'] ) ) {
+		$styles_output['css']          = WP_Style_Engine::compile_css( $parsed_styles['declarations'], $options['selector'] );
+		$styles_output['declarations'] = $parsed_styles['declarations'];
+		if ( ! empty( $options['context'] ) ) {
+			WP_Style_Engine::store_css_rule( $options['context'], $options['selector'], $parsed_styles['declarations'] );
+		}
+	}
+
+	if ( ! empty( $parsed_styles['classnames'] ) ) {
+		$styles_output['classnames'] = implode( ' ', array_unique( $parsed_styles['classnames'] ) );
+	}
+
+	return array_filter( $styles_output );
+}
+
+/**
+ * Returns compiled CSS from a collection of selectors and declarations.
+ * Useful for returning a compiled stylesheet from any collection of  CSS selector + declarations.
+ *
+ * Example usage:
+ * $css_rules = array( array( 'selector' => '.elephant-are-cool', 'declarations' => array( 'color' => 'gray', 'width' => '3em' ) ) );
+ * $css       = wp_style_engine_get_stylesheet_from_css_rules( $css_rules );
+ * // Returns `.elephant-are-cool{color:gray;width:3em}`.
+ *
+ * @since 6.1.0
+ *
+ * @param array $css_rules {
+ *     Required. A collection of CSS rules.
+ *
+ *     @type array ...$0 {
+ *         @type string   $selector     A CSS selector.
+ *         @type string[] $declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
+ *     }
+ * }
+ * @param array $options {
+ *     Optional. An array of options. Default empty array.
+ *
+ *     @type string|null $context  An identifier describing the origin of the style object, e.g., 'block-supports' or 'global-styles'. Default is 'block-supports'.
+ *                                 When set, the style engine will attempt to store the CSS rules.
+ *     @type bool        $optimize Whether to optimize the CSS output, e.g., combine rules. Default is `false`.
+ *     @type bool        $prettify Whether to add new lines and indents to output. Default is the test of whether the global constant `SCRIPT_DEBUG` is defined.
+ * }
+ *
+ * @return string A string of compiled CSS declarations, or empty string.
+ */
+function wp_style_engine_get_stylesheet_from_css_rules( $css_rules, $options = array() ) {
+	if ( empty( $css_rules ) ) {
+		return '';
+	}
+
+	$options = wp_parse_args(
+		$options,
+		array(
+			'context' => null,
+		)
+	);
+
+	$css_rule_objects = array();
+	foreach ( $css_rules as $css_rule ) {
+		if ( empty( $css_rule['selector'] ) || empty( $css_rule['declarations'] ) || ! is_array( $css_rule['declarations'] ) ) {
+			continue;
+		}
+
+		if ( ! empty( $options['context'] ) ) {
+			WP_Style_Engine::store_css_rule( $options['context'], $css_rule['selector'], $css_rule['declarations'] );
+		}
+
+		$css_rule_objects[] = new WP_Style_Engine_CSS_Rule( $css_rule['selector'], $css_rule['declarations'] );
+	}
+
+	if ( empty( $css_rule_objects ) ) {
+		return '';
+	}
+
+	return WP_Style_Engine::compile_stylesheet_from_css_rules( $css_rule_objects, $options );
+}
+
+/**
+ * Returns compiled CSS from a store, if found.
+ *
+ * @since 6.1.0
+ *
+ * @param string $context A valid context name, corresponding to an existing store key.
+ * @param array  $options {
+ *     Optional. An array of options. Default empty array.
+ *
+ *     @type bool $optimize Whether to optimize the CSS output, e.g., combine rules. Default is `false`.
+ *     @type bool $prettify Whether to add new lines and indents to output. Default is the test of whether the global constant `SCRIPT_DEBUG` is defined.
+ * }
+ *
+ * @return string A compiled CSS string.
+ */
+function wp_style_engine_get_stylesheet_from_context( $context, $options = array() ) {
+	return WP_Style_Engine::compile_stylesheet_from_css_rules( WP_Style_Engine::get_store( $context )->get_all_rules(), $options );
+}

wp-includes/style-engine/class-wp-style-engine-css-declarations.php

@@ -0,0 +1,189 @@
+<?php
+/**
+ * WP_Style_Engine_CSS_Declarations
+ *
+ * Holds, sanitizes and prints CSS rules declarations
+ *
+ * @package WordPress
+ * @subpackage StyleEngine
+ * @since 6.1.0
+ */
+
+/**
+ * Class WP_Style_Engine_CSS_Declarations.
+ *
+ * Holds, sanitizes, processes and prints CSS declarations for the style engine.
+ *
+ * @since 6.1.0
+ */
+class WP_Style_Engine_CSS_Declarations {
+
+	/**
+	 * An array of CSS declarations (property => value pairs).
+	 *
+	 * @since 6.1.0
+	 *
+	 * @var array
+	 */
+	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[] $declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
+	 */
+	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 array $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 array $properties An array of properties.
+	 *
+	 * @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 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   The spacer between the colon and the value. Defaults to an 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 Whether to add spacing, new lines and indents.
+	 * @param number $indent_count    The number of tab indents to apply to the rule. Applies if `prettify` is `true`.
+	 *
+	 * @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 );
+	}
+}