Scope page author stylesheet variants to routes in place

php-transformer/src/Css/CssSelectorListCompactor.php

@@ -10,13 +10,18 @@ final class CssSelectorListCompactor
     private static array $stylesheets = array();
     private static int $cachedBytes = 0;
 
-    public static function stylesheet(string $css): string
+    /**
+     * @param bool $markerLists Also merge arms that differ only by one
+     *     page-local marker class in a `:where()` into `:where(.m1,.m2,…)`.
+     *     Used for the site-wide sheet, where routes contribute marker arms.
+     */
+    public static function stylesheet(string $css, bool $markerLists = false): string
     {
-        $key = hash('sha256', $css);
+        $key = hash('sha256', $css) . ($markerLists ? ':m' : '');
         if ( isset(self::$stylesheets[ $key ]) ) {
             return self::$stylesheets[ $key ];
         }
-        $result = self::compactStylesheet($css);
+        $result = self::compactStylesheet($css, $markerLists);
         if ( count(self::$stylesheets) >= 128 || self::$cachedBytes + strlen($result) > 2097152 ) {
             self::$stylesheets = array();
             self::$cachedBytes = 0;
@@ -28,12 +33,161 @@ public static function stylesheet(string $css): string
         return $result;
     }
 
-    private static function compactStylesheet(string $css): string
+    private static function compactStylesheet(string $css, bool $markerLists = false): string
     {
         if ( ! str_contains($css, ',') || preg_match('/@namespace\b/i', $css) ) {
             return $css;
         }
-        return (new CssStylesheetTransformer())->transform($css, static fn(string $prelude): string => self::compact($prelude));
+        return (new CssStylesheetTransformer())->transform($css, static fn(string $prelude): string => self::compact($markerLists ? self::mergeMarkerLists($prelude) : $prelude));
+    }
+
+    /**
+     * Merge arms identical but for the page-local marker class inside one
+     * top-level `:where(.marker)`: `X:where(.m1)Y,X:where(.m2)Y` becomes
+     * `X:where(.m1,.m2)Y`. `:where()` weighs nothing and matches when any
+     * argument does, and every argument is a plain class, so the list is
+     * equivalent. expand() splits such lists back into arms.
+     */
+    public static function mergeMarkerLists(string $prelude): string
+    {
+        if ( ! str_contains($prelude, ',') || ! preg_match(self::PAGE_MARKER, $prelude) ) {
+            return $prelude;
+        }
+        $arms = CssStylesheetTransformer::splitSelectorList($prelude);
+        if ( null === $arms || count($arms) < 2 ) {
+            return $prelude;
+        }
+        $groups = array();
+        $order = array();
+        foreach ( $arms as $index => $arm ) {
+            $arm = trim($arm);
+            $key = "\1" . $index;
+            $markers = array();
+            if ( ! preg_match('/::|:(?:before|after|first-line|first-letter)\b/i', $arm) && ! str_contains($arm, '/*') && false === strpbrk($arm, '\\"\'') && preg_match_all(self::MARKER_WHERE, $arm, $matches, PREG_OFFSET_CAPTURE) ) {
+                foreach ( $matches[0] as $index2 => [$text, $offset] ) {
+                    $before = substr($arm, 0, $offset);
+                    if ( substr_count($before, '(') !== substr_count($before, ')') ) {
+                        continue;
+                    }
+                    $key = substr($arm, 0, $offset) . "\0" . substr($arm, $offset + strlen($text));
+                    $markers = explode(',', $matches[1][ $index2 ][0]);
+                    break;
+                }
+            }
+            if ( ! isset($groups[ $key ]) ) {
+                $order[] = $key;
+                $groups[ $key ] = array('arm' => $arm, 'markers' => array());
+            }
+            foreach ( $markers as $marker ) {
+                $groups[ $key ]['markers'][ $marker ] = true;
+            }
+        }
+        if ( count($order) === count($arms) ) {
+            return $prelude;
+        }
+        $output = array();
+        foreach ( $order as $key ) {
+            $group = $groups[ $key ];
+            if ( array() === $group['markers'] ) {
+                $output[] = $group['arm'];
+                continue;
+            }
+            [$prefix, $suffix] = explode("\0", $key, 2);
+            $output[] = $prefix . ':where(' . implode(',', array_keys($group['markers'])) . ')' . $suffix;
+        }
+        return implode(',', $output);
+    }
+
+    /** A `:where()` whose arguments are page-local marker classes only. */
+    private const MARKER_WHERE = '/:where\(((?:\.blocks-engine-[a-z-]+-[a-f0-9]{12}-[0-9]+,)*\.blocks-engine-[a-z-]+-[a-f0-9]{12}-[0-9]+)\)/';
+
+    /**
+     * Inverse of compact() for page-local marker lists: expand every whole
+     * compound `:is(m1,m2,…)` whose alternatives share one specificity in the
+     * strict grammar, and at least one names a page-local block marker, back
+     * into one arm per alternative. Equal specificity and strict alternatives
+     * make the arm list cascade-equivalent to the packed form, so two pages'
+     * projections of one source rule align arm by arm before reconciliation.
+     */
+    public static function expand(string $prelude): string
+    {
+        if ( ! preg_match(self::PAGE_MARKER, $prelude) ) {
+            return $prelude;
+        }
+        $arms = CssStylesheetTransformer::splitSelectorList($prelude);
+        if ( null === $arms ) {
+            return $prelude;
+        }
+        $output = array();
+        $changed = false;
+        while ( array() !== $arms ) {
+            $arm = trim((string) array_shift($arms));
+            $expanded = self::expandArm($arm);
+            if ( null === $expanded ) {
+                $output[] = $arm;
+                continue;
+            }
+            $changed = true;
+            array_unshift($arms, ...$expanded);
+        }
+        return $changed ? implode(',', $output) : $prelude;
+    }
+
+    /** Page-local block marker class (`blocks-engine-<kind>-<hash>-<n>`). */
+    public const PAGE_MARKER = '/(?<![a-zA-Z0-9_-])blocks-engine-[a-z-]+-[a-f0-9]{12}-[0-9]+(?![a-zA-Z0-9_-])/';
+
+    /** @return list<string>|null */
+    private static function expandArm(string $arm): ?array
+    {
+        // Richtext carriers use style attributes rather than marker classes.
+        $identity = 'blocks-engine-richtext-[a-f0-9]{12}-[0-9]+';
+        $richtext = '(?:mark\\[style\\*="--blocks-engine-richtext-marker:' . $identity . ';"\\]|mark\\[style\\$="--blocks-engine-richtext-marker:' . $identity . '"\\]|span\\[data-blocks-engine-richtext-marker="' . $identity . '"\\])';
+        if ( ! str_contains($arm, '\\') && preg_match_all('/:where\\(((?:' . $richtext . ',)+' . $richtext . ')\\)/', $arm, $lists, PREG_OFFSET_CAPTURE) ) {
+            foreach ( $lists[0] as $index => [$text, $offset] ) {
+                $before = substr($arm, 0, $offset);
+                if ( substr_count($before, '(') !== substr_count($before, ')') ) continue;
+                $suffix = substr($arm, $offset + strlen($text));
+                return array_map(static fn(string $marker): string => $before . ':where(' . $marker . ')' . $suffix, explode(',', $lists[1][$index][0]));
+            }
+        }
+        if ( false === strpbrk($arm, '\\"\'') && preg_match_all(self::MARKER_WHERE, $arm, $matches, PREG_OFFSET_CAPTURE) ) {
+            foreach ( $matches[0] as $index => [$text, $offset] ) {
+                $before = substr($arm, 0, $offset);
+                if ( ! str_contains($matches[1][ $index ][0], ',') || substr_count($before, '(') !== substr_count($before, ')') ) {
+                    continue;
+                }
+                $suffix = substr($arm, $offset + strlen($text));
+                return array_map(static fn(string $marker): string => $before . ':where(' . $marker . ')' . $suffix, explode(',', $matches[1][ $index ][0]));
+            }
+        }
+        if ( ! str_contains($arm, ':is(') ) {
+            return null;
+        }
+        $tokens = CssSelectorTokenizer::tokenize($arm);
+        if ( ! $tokens['supported'] ) {
+            return null;
+        }
+        foreach ( $tokens['compound_spans'] as $position => $span ) {
+            $compound = $tokens['compounds'][ $position ];
+            if ( ! str_starts_with($compound, ':is(') || ! str_ends_with($compound, ')') || ! preg_match(self::PAGE_MARKER, $compound) ) {
+                continue;
+            }
+            $alternatives = CssStylesheetTransformer::splitSelectorList(substr($compound, 4, -1));
+            if ( null === $alternatives || count($alternatives) < 2 ) {
+                continue;
+            }
+            $weights = array();
+            foreach ( $alternatives as $alternative ) {
+                $weights[ (string) self::plainCompoundWeight(trim($alternative)) ] = true;
+            }
+            if ( 1 !== count($weights) || isset($weights['']) ) {
+                continue;
+            }
+            $prefix = substr($arm, 0, $span['start']);
+            $suffix = substr($arm, $span['end']);
+            return array_map(static fn(string $alternative): string => $prefix . trim($alternative) . $suffix, $alternatives);
+        }
+        return null;
     }
 
     public static function compact(string $prelude): string

php-transformer/src/Css/CssSelectorMatcher.php

@@ -519,7 +519,7 @@ private static function parseCompound(string $source, int $sourceStart, bool $is
                         // A neutral native target can be a complete descendant
                         // path, or contain nested shims. Flattening it into one
                         // compound changes both its match and its specificity.
-                        if (($argument['supported'] ?? false) && (count($argument['compounds']) > 1 || !empty($leaf['not']) || !empty($leaf['any']) || !empty($leaf['first_child']) || !empty($leaf['last_child']) || null !== ($leaf['nth_child'] ?? null) || null !== ($leaf['nth_type'] ?? null))) {
+                        if (($argument['supported'] ?? false) && (count($argument['compounds']) > 1 || !empty($leaf['root']) || !empty($leaf['not']) || !empty($leaf['any']) || !empty($leaf['first_child']) || !empty($leaf['last_child']) || null !== ($leaf['nth_child'] ?? null) || null !== ($leaf['nth_type'] ?? null))) {
                             $group = self::parseSelectorListArgument($alternatives, 'where' === $lowerName);
                             if (null === $group) return null;
                             $compound['any'][] = $group;
@@ -582,7 +582,9 @@ private static function parseCompound(string $source, int $sourceStart, bool $is
                     if ( '' === $argument ) {
                         return null;
                     }
-                    $negated = self::parseUncached($argument);
+                    $alternatives = CssStylesheetTransformer::splitSelectorList($argument);
+                    if (null === $alternatives) return null;
+                    $negated = self::parseUncached(count($alternatives) > 1 ? ':is(' . $argument . ')' : $argument);
                     if ( ! ($negated['supported'] ?? false) || null !== ($negated['pseudo_state_suffix_span'] ?? null) ) {
                         return null;
                     }