--- /dev/null
+<?php
+/**
+ * @file
+ * @license https://opensource.org/licenses/Apache-2.0 Apache-2.0
+ */
+
+namespace Wikimedia\CSS\Grammar;
+
+use Wikimedia\CSS\Objects\ComponentValueList;
+use Wikimedia\CSS\Objects\Token;
+
+/**
+ * Matcher that matches a sub-Matcher a certain number of times
+ * ("?", "*", "+", "#", "{A,B}" multipliers)
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#component-multipliers
+ */
+class Quantifier extends Matcher {
+ /** @var Matcher */
+ protected $matcher;
+
+ /** @var int */
+ protected $min, $max;
+
+ /** @var bool Whether matches are comma-separated */
+ protected $commas;
+
+ /**
+ * @param Matcher $matcher
+ * @param int|float $min Minimum number of matches
+ * @param int|float $max Maximum number of matches
+ * @param bool $commas Whether matches are comma-separated
+ */
+ public function __construct( Matcher $matcher, $min, $max, $commas ) {
+ $this->matcher = $matcher;
+ $this->min = $min;
+ $this->max = $max;
+ $this->commas = (bool)$commas;
+ }
+
+ /**
+ * Implements "?": 0 or 1 matches
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#mult-opt
+ * @param Matcher $matcher
+ * @return static
+ */
+ public static function optional( Matcher $matcher ) {
+ return new static( $matcher, 0, 1, false );
+ }
+
+ /**
+ * Implements "*": 0 or more matches
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#mult-zero-plus
+ * @param Matcher $matcher
+ * @return static
+ */
+ public static function star( Matcher $matcher ) {
+ return new static( $matcher, 0, INF, false );
+ }
+
+ /**
+ * Implements "+": 1 or more matches
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#mult-one-plus
+ * @param Matcher $matcher
+ * @return static
+ */
+ public static function plus( Matcher $matcher ) {
+ return new static( $matcher, 1, INF, false );
+ }
+
+ /**
+ * Implements "{A,B}": Between A and B matches
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#mult-num-range
+ * @param Matcher $matcher
+ * @param int|float $min Minimum number of matches
+ * @param int|float $max Maximum number of matches
+ * @return static
+ */
+ public static function count( Matcher $matcher, $min, $max ) {
+ return new static( $matcher, $min, $max, false );
+ }
+
+ /**
+ * Implements "#" and "#{A,B}": Between A and B matches, comma-separated
+ * @see https://www.w3.org/TR/2016/CR-css-values-3-20160929/#mult-comma
+ * @param Matcher $matcher
+ * @param int|float $min Minimum number of matches
+ * @param int|float $max Maximum number of matches
+ * @return static
+ */
+ public static function hash( Matcher $matcher, $min = 1, $max = INF ) {
+ return new static( $matcher, $min, $max, true );
+ }
+
+ protected function generateMatches( ComponentValueList $values, $start, array $options ) {
+ $used = [];
+
+ // Maintain a stack of matches for backtracking purposes.
+ $stack = [
+ [ new Match( $values, $start, 0 ), $this->matcher->generateMatches( $values, $start, $options ) ]
+ ];
+ do {
+ /** @var $lastMatch Match */
+ /** @var $iter \Iterator<Match> */
+ list( $lastMatch, $iter ) = $stack[count( $stack ) - 1];
+
+ // If the top of the stack has no more matches, pop it, maybe
+ // yield the last matched position, and loop.
+ if ( !$iter->valid() ) {
+ array_pop( $stack );
+ $ct = count( $stack );
+ $pos = $lastMatch->getNext();
+ if ( $ct >= $this->min && $ct <= $this->max ) {
+ $newMatch = $this->makeMatch( $values, $start, $pos, $lastMatch, $stack );
+ $mid = $newMatch->getUniqueID();
+ if ( !isset( $used[$mid] ) ) {
+ $used[$mid] = 1;
+ yield $newMatch;
+ }
+ }
+ continue;
+ }
+
+ // Find the next match for the current top of the stack.
+ $match = $iter->current();
+ $iter->next();
+
+ // Quantifiers don't work well when the quantified thing can be empty.
+ if ( $match->getLength() === 0 ) {
+ throw new \UnexpectedValueException( 'Empty match in quantifier!' );
+ }
+
+ $nextFrom = $match->getNext();
+
+ // There can only be more matches after this one if we haven't
+ // reached our maximum yet.
+ $canBeMore = count( $stack ) < $this->max;
+
+ // Commas are slightly tricky:
+ // 1. If there is a following comma, start the next Matcher after it.
+ // 2. If not, there can't be any more Matchers following.
+ // And in either case optional whitespace is always allowed.
+ if ( $this->commas ) {
+ $n = $nextFrom;
+ if ( isset( $values[$n] ) && $values[$n] instanceof Token &&
+ $values[$n]->type() === Token::T_WHITESPACE
+ ) {
+ $n = $this->next( $values, $n, [ 'skip-whitespace' => true ] + $options );
+ }
+ if ( isset( $values[$n] ) && $values[$n] instanceof Token &&
+ $values[$n]->type() === Token::T_COMMA
+ ) {
+ $nextFrom = $this->next( $values, $n, [ 'skip-whitespace' => true ] + $options );
+ } else {
+ $canBeMore = false;
+ }
+ }
+
+ // If there can be more matches, push another one onto the stack
+ // and try it. Otherwise yield and continue with the current match.
+ if ( $canBeMore ) {
+ $stack[] = [ $match, $this->matcher->generateMatches( $values, $nextFrom, $options ) ];
+ } else {
+ $ct = count( $stack );
+ $pos = $match->getNext();
+ if ( $ct >= $this->min && $ct <= $this->max ) {
+ $newMatch = $this->makeMatch( $values, $start, $pos, $match, $stack );
+ $mid = $newMatch->getUniqueID();
+ if ( !isset( $used[$mid] ) ) {
+ $used[$mid] = 1;
+ yield $newMatch;
+ }
+ }
+ }
+ } while ( $stack );
+ }
+}
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