`wp_get_global_styles`: allow transforming the CSS Custom Properties into the values they represent.

Props samnajian, ramonopoly, isabel_brison.
Fixes #58588.

Built from https://develop.svn.wordpress.org/trunk@55986


git-svn-id: http://core.svn.wordpress.org/trunk@55498 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-theme-json.php

@@ -3529,4 +3529,77 @@ class WP_Theme_JSON {
 		return $tree;
 	}
 
+	/**
+	 * Replaces CSS variables with their values in place.
+	 *
+	 * @since 6.3.0
+	 * @param array $styles CSS declarations to convert.
+	 * @param array $values key => value pairs to use for replacement.
+	 * @return array
+	 */
+	private static function convert_variables_to_value( $styles, $values ) {
+		foreach ( $styles as $key => $style ) {
+			if ( is_array( $style ) ) {
+				$styles[ $key ] = self::convert_variables_to_value( $style, $values );
+				continue;
+			}
+
+			if ( 0 <= strpos( $style, 'var(' ) ) {
+				// find all the variables in the string in the form of var(--variable-name, fallback), with fallback in the second capture group.
+
+				$has_matches = preg_match_all( '/var\(([^),]+)?,?\s?(\S+)?\)/', $style, $var_parts );
+
+				if ( $has_matches ) {
+					$resolved_style = $styles[ $key ];
+					foreach ( $var_parts[1] as $index => $var_part ) {
+						$key_in_values   = 'var(' . $var_part . ')';
+						$rule_to_replace = $var_parts[0][ $index ]; // the css rule to replace e.g. var(--wp--preset--color--vivid-green-cyan).
+						$fallback        = $var_parts[2][ $index ]; // the fallback value.
+						$resolved_style  = str_replace(
+							array(
+								$rule_to_replace,
+								$fallback,
+							),
+							array(
+								isset( $values[ $key_in_values ] ) ? $values[ $key_in_values ] : $rule_to_replace,
+								isset( $values[ $fallback ] ) ? $values[ $fallback ] : $fallback,
+							),
+							$resolved_style
+						);
+					}
+					$styles[ $key ] = $resolved_style;
+				}
+			}
+		}
+
+		return $styles;
+	}
+
+	/**
+	 * Resolves the values of CSS variables in the given styles.
+	 *
+	 * @since 6.3.0
+	 * @param WP_Theme_JSON $theme_json The theme json resolver.
+	 *
+	 * @return WP_Theme_JSON The $theme_json with resolved variables.
+	 */
+	public static function resolve_variables( $theme_json ) {
+		$settings    = $theme_json->get_settings();
+		$styles      = $theme_json->get_raw_data()['styles'];
+		$preset_vars = static::compute_preset_vars( $settings, static::VALID_ORIGINS );
+		$theme_vars  = static::compute_theme_vars( $settings );
+		$vars        = array_reduce(
+			array_merge( $preset_vars, $theme_vars ),
+			function( $carry, $item ) {
+				$name                    = $item['name'];
+				$carry[ "var({$name})" ] = $item['value'];
+				return $carry;
+			},
+			array()
+		);
+
+		$theme_json->theme_json['styles'] = self::convert_variables_to_value( $styles, $vars );
+		return $theme_json;
+	}
+
 }

wp-includes/global-styles-and-settings.php

@@ -92,8 +92,10 @@ function wp_get_global_settings( $path = array(), $context = array() ) {
  * Gets the styles resulting of merging core, theme, and user data.
  *
  * @since 5.9.0
- * @since 6.3.0 the internal format "var:preset|color|secondary" is always resolved
- *              to the standard form "var(--wp--preset--font-size--small)".
+ * @since 6.3.0 the internal link format "var:preset|color|secondary" is resolved
+ *              to "var(--wp--preset--font-size--small)" so consumers don't have to.
+ * @since 6.3.0 `transforms` is now usable in the `context` parameter. In case [`transforms`]['resolve_variables']
+ *              is defined, variables are resolved to their value in the styles.
  *
  * @param array $path    Path to the specific style to retrieve. Optional.
  *                       If empty, will return all styles.
@@ -105,6 +107,9 @@ function wp_get_global_settings( $path = array(), $context = array() ) {
  *     @type string $origin     Which origin to take data from.
  *                              Valid values are 'all' (core, theme, and user) or 'base' (core and theme).
  *                              If empty or unknown, 'all' is used.
+ *     @type array $transforms Which transformation(s) to apply.
+ *                              Valid value is array( 'resolve-variables' ).
+ *                              If defined, variables are resolved to their value in the styles.
  * }
  * @return mixed The styles array or individual style value to retrieve.
  */
@@ -117,11 +122,20 @@ function wp_get_global_styles( $path = array(), $context = array() ) {
 	if ( isset( $context['origin'] ) && 'base' === $context['origin'] ) {
 		$origin = 'theme';
 	}
-	$styles = WP_Theme_JSON_Resolver::get_merged_data( $origin )->get_raw_data()['styles'];
 
+	$resolve_variables = isset( $context['transforms'] )
+	&& is_array( $context['transforms'] )
+	&& in_array( 'resolve-variables', $context['transforms'], true );
+
+	$merged_data = WP_Theme_JSON_Resolver::get_merged_data( $origin );
+	if ( $resolve_variables ) {
+		$merged_data = WP_Theme_JSON::resolve_variables( $merged_data );
+	}
+	$styles = $merged_data->get_raw_data()['styles'];
 	return _wp_array_get( $styles, $path, $styles );
 }
 
+
 /**
  * Returns the stylesheet resulting of merging core, theme, and user data.
  *

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55985';
+$wp_version = '6.3-alpha-55986';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.