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   1  <?php
   2  
   3  /*
   4   * This file is part of the Symfony package.
   5   *
   6   * (c) Fabien Potencier <fabien@symfony.com>
   7   *
   8   * For the full copyright and license information, please view the LICENSE
   9   * file that was distributed with this source code.
  10   */
  11  
  12  namespace Symfony\Component\CssSelector\Parser;
  13  
  14  use Symfony\Component\CssSelector\Exception\InternalErrorException;
  15  use Symfony\Component\CssSelector\Exception\SyntaxErrorException;
  16  
  17  /**
  18   * CSS selector token stream.
  19   *
  20   * This component is a port of the Python cssselect library,
  21   * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
  22   *
  23   * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
  24   *
  25   * @internal
  26   */
  27  class TokenStream
  28  {
  29      /**
  30       * @var Token[]
  31       */
  32      private $tokens = [];
  33  
  34      /**
  35       * @var Token[]
  36       */
  37      private $used = [];
  38  
  39      /**
  40       * @var int
  41       */
  42      private $cursor = 0;
  43  
  44      /**
  45       * @var Token|null
  46       */
  47      private $peeked;
  48  
  49      /**
  50       * @var bool
  51       */
  52      private $peeking = false;
  53  
  54      /**
  55       * Pushes a token.
  56       *
  57       * @return $this
  58       */
  59      public function push(Token $token): self
  60      {
  61          $this->tokens[] = $token;
  62  
  63          return $this;
  64      }
  65  
  66      /**
  67       * Freezes stream.
  68       *
  69       * @return $this
  70       */
  71      public function freeze(): self
  72      {
  73          return $this;
  74      }
  75  
  76      /**
  77       * Returns next token.
  78       *
  79       * @throws InternalErrorException If there is no more token
  80       */
  81      public function getNext(): Token
  82      {
  83          if ($this->peeking) {
  84              $this->peeking = false;
  85              $this->used[] = $this->peeked;
  86  
  87              return $this->peeked;
  88          }
  89  
  90          if (!isset($this->tokens[$this->cursor])) {
  91              throw new InternalErrorException('Unexpected token stream end.');
  92          }
  93  
  94          return $this->tokens[$this->cursor++];
  95      }
  96  
  97      /**
  98       * Returns peeked token.
  99       */
 100      public function getPeek(): Token
 101      {
 102          if (!$this->peeking) {
 103              $this->peeked = $this->getNext();
 104              $this->peeking = true;
 105          }
 106  
 107          return $this->peeked;
 108      }
 109  
 110      /**
 111       * Returns used tokens.
 112       *
 113       * @return Token[]
 114       */
 115      public function getUsed(): array
 116      {
 117          return $this->used;
 118      }
 119  
 120      /**
 121       * Returns nex identifier token.
 122       *
 123       * @return string The identifier token value
 124       *
 125       * @throws SyntaxErrorException If next token is not an identifier
 126       */
 127      public function getNextIdentifier(): string
 128      {
 129          $next = $this->getNext();
 130  
 131          if (!$next->isIdentifier()) {
 132              throw SyntaxErrorException::unexpectedToken('identifier', $next);
 133          }
 134  
 135          return $next->getValue();
 136      }
 137  
 138      /**
 139       * Returns nex identifier or star delimiter token.
 140       *
 141       * @return string|null The identifier token value or null if star found
 142       *
 143       * @throws SyntaxErrorException If next token is not an identifier or a star delimiter
 144       */
 145      public function getNextIdentifierOrStar(): ?string
 146      {
 147          $next = $this->getNext();
 148  
 149          if ($next->isIdentifier()) {
 150              return $next->getValue();
 151          }
 152  
 153          if ($next->isDelimiter(['*'])) {
 154              return null;
 155          }
 156  
 157          throw SyntaxErrorException::unexpectedToken('identifier or "*"', $next);
 158      }
 159  
 160      /**
 161       * Skips next whitespace if any.
 162       */
 163      public function skipWhitespace()
 164      {
 165          $peek = $this->getPeek();
 166  
 167          if ($peek->isWhitespace()) {
 168              $this->getNext();
 169          }
 170      }
 171  }