vendor/twig/twig/src/Lexer.php line 440

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  1. <?php
  3. /*
  4.  * This file is part of Twig.
  5.  *
  6.  * (c) Fabien Potencier
  7.  * (c) Armin Ronacher
  8.  *
  9.  * For the full copyright and license information, please view the LICENSE
  10.  * file that was distributed with this source code.
  11.  */
  13. namespace Twig;
  15. use Twig\Error\SyntaxError;
  17. /**
  18.  * @author Fabien Potencier <fabien@symfony.com>
  19.  */
  20. class Lexer
  21. {
  22.     private $isInitialized = false;
  24.     private $tokens;
  25.     private $code;
  26.     private $cursor;
  27.     private $lineno;
  28.     private $end;
  29.     private $state;
  30.     private $states;
  31.     private $brackets;
  32.     private $env;
  33.     private $source;
  34.     private $options;
  35.     private $regexes;
  36.     private $position;
  37.     private $positions;
  38.     private $currentVarBlockLine;
  40.     public const STATE_DATA = 0;
  41.     public const STATE_BLOCK = 1;
  42.     public const STATE_VAR = 2;
  43.     public const STATE_STRING = 3;
  44.     public const STATE_INTERPOLATION = 4;
  46.     public const REGEX_NAME = '/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/A';
  47.     public const REGEX_NUMBER = '/[0-9]+(?:\.[0-9]+)?([Ee][\+\-][0-9]+)?/A';
  48.     public const REGEX_STRING = '/"([^#"\\\\]*(?:\\\\.[^#"\\\\]*)*)"|\'([^\'\\\\]*(?:\\\\.[^\'\\\\]*)*)\'/As';
  49.     public const REGEX_DQ_STRING_DELIM = '/"/A';
  50.     public const REGEX_DQ_STRING_PART = '/[^#"\\\\]*(?:(?:\\\\.|#(?!\{))[^#"\\\\]*)*/As';
  51.     public const PUNCTUATION = '()[]{}?:.,|';
  53.     private const SPECIAL_CHARS = [
  54.         'f' => "\f",
  55.         'n' => "\n",
  56.         'r' => "\r",
  57.         't' => "\t",
  58.         'v' => "\v",
  59.     ];
  61.     public function __construct(Environment $env, array $options = [])
  62.     {
  63.         $this->env = $env;
  65.         $this->options = array_merge([
  66.             'tag_comment' => ['{#', '#}'],
  67.             'tag_block' => ['{%', '%}'],
  68.             'tag_variable' => ['{{', '}}'],
  69.             'whitespace_trim' => '-',
  70.             'whitespace_line_trim' => '~',
  71.             'whitespace_line_chars' => ' \t\0\x0B',
  72.             'interpolation' => ['#{', '}'],
  73.         ], $options);
  74.     }
  76.     private function initialize()
  77.     {
  78.         if ($this->isInitialized) {
  79.             return;
  80.         }
  82.         // when PHP 7.3 is the min version, we will be able to remove the '#' part in preg_quote as it's part of the default
  83.         $this->regexes = [
  84.             // }}
  85.             'lex_var' => '{
  86.                 \s*
  87.                 (?:'.
  88.                     preg_quote($this->options['whitespace_trim'].$this->options['tag_variable'][1], '#').'\s*'. // -}}\s*
  89.                     '|'.
  90.                     preg_quote($this->options['whitespace_line_trim'].$this->options['tag_variable'][1], '#').'['.$this->options['whitespace_line_chars'].']*'. // ~}}[ \t\0\x0B]*
  91.                     '|'.
  92.                     preg_quote($this->options['tag_variable'][1], '#'). // }}
  93.                 ')
  94.             }Ax',
  96.             // %}
  97.             'lex_block' => '{
  98.                 \s*
  99.                 (?:'.
  100.                     preg_quote($this->options['whitespace_trim'].$this->options['tag_block'][1], '#').'\s*\n?'. // -%}\s*\n?
  101.                     '|'.
  102.                     preg_quote($this->options['whitespace_line_trim'].$this->options['tag_block'][1], '#').'['.$this->options['whitespace_line_chars'].']*'. // ~%}[ \t\0\x0B]*
  103.                     '|'.
  104.                     preg_quote($this->options['tag_block'][1], '#').'\n?'. // %}\n?
  105.                 ')
  106.             }Ax',
  108.             // {% endverbatim %}
  109.             'lex_raw_data' => '{'.
  110.                 preg_quote($this->options['tag_block'][0], '#'). // {%
  111.                 '('.
  112.                     $this->options['whitespace_trim']. // -
  113.                     '|'.
  114.                     $this->options['whitespace_line_trim']. // ~
  115.                 ')?\s*endverbatim\s*'.
  116.                 '(?:'.
  117.                     preg_quote($this->options['whitespace_trim'].$this->options['tag_block'][1], '#').'\s*'. // -%}
  118.                     '|'.
  119.                     preg_quote($this->options['whitespace_line_trim'].$this->options['tag_block'][1], '#').'['.$this->options['whitespace_line_chars'].']*'. // ~%}[ \t\0\x0B]*
  120.                     '|'.
  121.                     preg_quote($this->options['tag_block'][1], '#'). // %}
  122.                 ')
  123.             }sx',
  125.             'operator' => $this->getOperatorRegex(),
  127.             // #}
  128.             'lex_comment' => '{
  129.                 (?:'.
  130.                     preg_quote($this->options['whitespace_trim'].$this->options['tag_comment'][1], '#').'\s*\n?'. // -#}\s*\n?
  131.                     '|'.
  132.                     preg_quote($this->options['whitespace_line_trim'].$this->options['tag_comment'][1], '#').'['.$this->options['whitespace_line_chars'].']*'. // ~#}[ \t\0\x0B]*
  133.                     '|'.
  134.                     preg_quote($this->options['tag_comment'][1], '#').'\n?'. // #}\n?
  135.                 ')
  136.             }sx',
  138.             // verbatim %}
  139.             'lex_block_raw' => '{
  140.                 \s*verbatim\s*
  141.                 (?:'.
  142.                     preg_quote($this->options['whitespace_trim'].$this->options['tag_block'][1], '#').'\s*'. // -%}\s*
  143.                     '|'.
  144.                     preg_quote($this->options['whitespace_line_trim'].$this->options['tag_block'][1], '#').'['.$this->options['whitespace_line_chars'].']*'. // ~%}[ \t\0\x0B]*
  145.                     '|'.
  146.                     preg_quote($this->options['tag_block'][1], '#'). // %}
  147.                 ')
  148.             }Asx',
  150.             'lex_block_line' => '{\s*line\s+(\d+)\s*'.preg_quote($this->options['tag_block'][1], '#').'}As',
  152.             // {{ or {% or {#
  153.             'lex_tokens_start' => '{
  154.                 ('.
  155.                     preg_quote($this->options['tag_variable'][0], '#'). // {{
  156.                     '|'.
  157.                     preg_quote($this->options['tag_block'][0], '#'). // {%
  158.                     '|'.
  159.                     preg_quote($this->options['tag_comment'][0], '#'). // {#
  160.                 ')('.
  161.                     preg_quote($this->options['whitespace_trim'], '#'). // -
  162.                     '|'.
  163.                     preg_quote($this->options['whitespace_line_trim'], '#'). // ~
  164.                 ')?
  165.             }sx',
  166.             'interpolation_start' => '{'.preg_quote($this->options['interpolation'][0], '#').'\s*}A',
  167.             'interpolation_end' => '{\s*'.preg_quote($this->options['interpolation'][1], '#').'}A',
  168.         ];
  170.         $this->isInitialized = true;
  171.     }
  173.     public function tokenize(Source $source): TokenStream
  174.     {
  175.         $this->initialize();
  177.         $this->source = $source;
  178.         $this->code = str_replace(["\r\n", "\r"], "\n", $source->getCode());
  179.         $this->cursor = 0;
  180.         $this->lineno = 1;
  181.         $this->end = \strlen($this->code);
  182.         $this->tokens = [];
  183.         $this->state = self::STATE_DATA;
  184.         $this->states = [];
  185.         $this->brackets = [];
  186.         $this->position = -1;
  188.         // find all token starts in one go
  189.         preg_match_all($this->regexes['lex_tokens_start'], $this->code, $matches, \PREG_OFFSET_CAPTURE);
  190.         $this->positions = $matches;
  192.         while ($this->cursor < $this->end) {
  193.             // dispatch to the lexing functions depending
  194.             // on the current state
  195.             switch ($this->state) {
  196.                 case self::STATE_DATA:
  197.                     $this->lexData();
  198.                     break;
  200.                 case self::STATE_BLOCK:
  201.                     $this->lexBlock();
  202.                     break;
  204.                 case self::STATE_VAR:
  205.                     $this->lexVar();
  206.                     break;
  208.                 case self::STATE_STRING:
  209.                     $this->lexString();
  210.                     break;
  212.                 case self::STATE_INTERPOLATION:
  213.                     $this->lexInterpolation();
  214.                     break;
  215.             }
  216.         }
  218.         $this->pushToken(Token::EOF_TYPE);
  220.         if (!empty($this->brackets)) {
  221.             [$expect, $lineno] = array_pop($this->brackets);
  222.             throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
  223.         }
  225.         return new TokenStream($this->tokens, $this->source);
  226.     }
  228.     private function lexData(): void
  229.     {
  230.         // if no matches are left we return the rest of the template as simple text token
  231.         if ($this->position == \count($this->positions[0]) - 1) {
  232.             $this->pushToken(Token::TEXT_TYPE, substr($this->code, $this->cursor));
  233.             $this->cursor = $this->end;
  235.             return;
  236.         }
  238.         // Find the first token after the current cursor
  239.         $position = $this->positions[0][++$this->position];
  240.         while ($position[1] < $this->cursor) {
  241.             if ($this->position == \count($this->positions[0]) - 1) {
  242.                 return;
  243.             }
  244.             $position = $this->positions[0][++$this->position];
  245.         }
  247.         // push the template text first
  248.         $text = $textContent = substr($this->code, $this->cursor, $position[1] - $this->cursor);
  250.         // trim?
  251.         if (isset($this->positions[2][$this->position][0])) {
  252.             if ($this->options['whitespace_trim'] === $this->positions[2][$this->position][0]) {
  253.                 // whitespace_trim detected ({%-, {{- or {#-)
  254.                 $text = rtrim($text);
  255.             } elseif ($this->options['whitespace_line_trim'] === $this->positions[2][$this->position][0]) {
  256.                 // whitespace_line_trim detected ({%~, {{~ or {#~)
  257.                 // don't trim \r and \n
  258.                 $text = rtrim($text, " \t\0\x0B");
  259.             }
  260.         }
  261.         $this->pushToken(Token::TEXT_TYPE, $text);
  262.         $this->moveCursor($textContent.$position[0]);
  264.         switch ($this->positions[1][$this->position][0]) {
  265.             case $this->options['tag_comment'][0]:
  266.                 $this->lexComment();
  267.                 break;
  269.             case $this->options['tag_block'][0]:
  270.                 // raw data?
  271.                 if (preg_match($this->regexes['lex_block_raw'], $this->code, $match, 0, $this->cursor)) {
  272.                     $this->moveCursor($match[0]);
  273.                     $this->lexRawData();
  274.                 // {% line \d+ %}
  275.                 } elseif (preg_match($this->regexes['lex_block_line'], $this->code, $match, 0, $this->cursor)) {
  276.                     $this->moveCursor($match[0]);
  277.                     $this->lineno = (int) $match[1];
  278.                 } else {
  279.                     $this->pushToken(Token::BLOCK_START_TYPE);
  280.                     $this->pushState(self::STATE_BLOCK);
  281.                     $this->currentVarBlockLine = $this->lineno;
  282.                 }
  283.                 break;
  285.             case $this->options['tag_variable'][0]:
  286.                 $this->pushToken(Token::VAR_START_TYPE);
  287.                 $this->pushState(self::STATE_VAR);
  288.                 $this->currentVarBlockLine = $this->lineno;
  289.                 break;
  290.         }
  291.     }
  293.     private function lexBlock(): void
  294.     {
  295.         if (empty($this->brackets) && preg_match($this->regexes['lex_block'], $this->code, $match, 0, $this->cursor)) {
  296.             $this->pushToken(Token::BLOCK_END_TYPE);
  297.             $this->moveCursor($match[0]);
  298.             $this->popState();
  299.         } else {
  300.             $this->lexExpression();
  301.         }
  302.     }
  304.     private function lexVar(): void
  305.     {
  306.         if (empty($this->brackets) && preg_match($this->regexes['lex_var'], $this->code, $match, 0, $this->cursor)) {
  307.             $this->pushToken(Token::VAR_END_TYPE);
  308.             $this->moveCursor($match[0]);
  309.             $this->popState();
  310.         } else {
  311.             $this->lexExpression();
  312.         }
  313.     }
  315.     private function lexExpression(): void
  316.     {
  317.         // whitespace
  318.         if (preg_match('/\s+/A', $this->code, $match, 0, $this->cursor)) {
  319.             $this->moveCursor($match[0]);
  321.             if ($this->cursor >= $this->end) {
  322.                 throw new SyntaxError(\sprintf('Unclosed "%s".', self::STATE_BLOCK === $this->state ? 'block' : 'variable'), $this->currentVarBlockLine, $this->source);
  323.             }
  324.         }
  326.         // spread operator
  327.         if ('.' === $this->code[$this->cursor] && ($this->cursor + 2 < $this->end) && '.' === $this->code[$this->cursor + 1] && '.' === $this->code[$this->cursor + 2]) {
  328.             $this->pushToken(Token::SPREAD_TYPE, '...');
  329.             $this->moveCursor('...');
  330.         }
  331.         // arrow function
  332.         elseif ('=' === $this->code[$this->cursor] && ($this->cursor + 1 < $this->end) && '>' === $this->code[$this->cursor + 1]) {
  333.             $this->pushToken(Token::ARROW_TYPE, '=>');
  334.             $this->moveCursor('=>');
  335.         }
  336.         // operators
  337.         elseif (preg_match($this->regexes['operator'], $this->code, $match, 0, $this->cursor)) {
  338.             $this->pushToken(Token::OPERATOR_TYPE, preg_replace('/\s+/', ' ', $match[0]));
  339.             $this->moveCursor($match[0]);
  340.         }
  341.         // names
  342.         elseif (preg_match(self::REGEX_NAME, $this->code, $match, 0, $this->cursor)) {
  343.             $this->pushToken(Token::NAME_TYPE, $match[0]);
  344.             $this->moveCursor($match[0]);
  345.         }
  346.         // numbers
  347.         elseif (preg_match(self::REGEX_NUMBER, $this->code, $match, 0, $this->cursor)) {
  348.             $number = (float) $match[0];  // floats
  349.             if (ctype_digit($match[0]) && $number <= \PHP_INT_MAX) {
  350.                 $number = (int) $match[0]; // integers lower than the maximum
  351.             }
  352.             $this->pushToken(Token::NUMBER_TYPE, $number);
  353.             $this->moveCursor($match[0]);
  354.         }
  355.         // punctuation
  356.         elseif (str_contains(self::PUNCTUATION, $this->code[$this->cursor])) {
  357.             // opening bracket
  358.             if (str_contains('([{', $this->code[$this->cursor])) {
  359.                 $this->brackets[] = [$this->code[$this->cursor], $this->lineno];
  360.             }
  361.             // closing bracket
  362.             elseif (str_contains(')]}', $this->code[$this->cursor])) {
  363.                 if (empty($this->brackets)) {
  364.                     throw new SyntaxError(\sprintf('Unexpected "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
  365.                 }
  367.                 [$expect, $lineno] = array_pop($this->brackets);
  368.                 if ($this->code[$this->cursor] != strtr($expect, '([{', ')]}')) {
  369.                     throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
  370.                 }
  371.             }
  373.             $this->pushToken(Token::PUNCTUATION_TYPE, $this->code[$this->cursor]);
  374.             ++$this->cursor;
  375.         }
  376.         // strings
  377.         elseif (preg_match(self::REGEX_STRING, $this->code, $match, 0, $this->cursor)) {
  378.             $this->pushToken(Token::STRING_TYPE, $this->stripcslashes(substr($match[0], 1, -1), substr($match[0], 0, 1)));
  379.             $this->moveCursor($match[0]);
  380.         }
  381.         // opening double quoted string
  382.         elseif (preg_match(self::REGEX_DQ_STRING_DELIM, $this->code, $match, 0, $this->cursor)) {
  383.             $this->brackets[] = ['"', $this->lineno];
  384.             $this->pushState(self::STATE_STRING);
  385.             $this->moveCursor($match[0]);
  386.         }
  387.         // unlexable
  388.         else {
  389.             throw new SyntaxError(\sprintf('Unexpected character "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
  390.         }
  391.     }
  393.     private function stripcslashes(string $str, string $quoteType): string
  394.     {
  395.         $result = '';
  396.         $length = \strlen($str);
  398.         $i = 0;
  399.         while ($i < $length) {
  400.             if (false === $pos = strpos($str, '\\', $i)) {
  401.                 $result .= substr($str, $i);
  402.                 break;
  403.             }
  405.             $result .= substr($str, $i, $pos - $i);
  406.             $i = $pos + 1;
  408.             if ($i >= $length) {
  409.                 $result .= '\\';
  410.                 break;
  411.             }
  413.             $nextChar = $str[$i];
  415.             if (isset(self::SPECIAL_CHARS[$nextChar])) {
  416.                 $result .= self::SPECIAL_CHARS[$nextChar];
  417.             } elseif ('\\' === $nextChar) {
  418.                 $result .= $nextChar;
  419.             } elseif ("'" === $nextChar || '"' === $nextChar) {
  420.                 if ($nextChar !== $quoteType) {
  421.                     trigger_deprecation('twig/twig', '3.12', 'Character "%s" at position %d should not be escaped; the "\" character is ignored in Twig v3 but will not be in v4. Please remove the extra "\" character.', $nextChar, $i + 1);
  422.                 }
  423.                 $result .= $nextChar;
  424.             } elseif ('#' === $nextChar && $i + 1 < $length && '{' === $str[$i + 1]) {
  425.                 $result .= '#{';
  426.                 ++$i;
  427.             } elseif ('x' === $nextChar && $i + 1 < $length && ctype_xdigit($str[$i + 1])) {
  428.                 $hex = $str[++$i];
  429.                 if ($i + 1 < $length && ctype_xdigit($str[$i + 1])) {
  430.                     $hex .= $str[++$i];
  431.                 }
  432.                 $result .= \chr(hexdec($hex));
  433.             } elseif (ctype_digit($nextChar) && $nextChar < '8') {
  434.                 $octal = $nextChar;
  435.                 while ($i + 1 < $length && ctype_digit($str[$i + 1]) && $str[$i + 1] < '8' && \strlen($octal) < 3) {
  436.                     $octal .= $str[++$i];
  437.                 }
  438.                 $result .= \chr(octdec($octal));
  439.             } else {
  440.                 trigger_deprecation('twig/twig', '3.12', 'Character "%s" at position %d should not be escaped; the "\" character is ignored in Twig v3 but will not be in v4. Please remove the extra "\" character.', $nextChar, $i + 1);
  441.                 $result .= $nextChar;
  442.             }
  444.             ++$i;
  445.         }
  447.         return $result;
  448.     }
  450.     private function lexRawData(): void
  451.     {
  452.         if (!preg_match($this->regexes['lex_raw_data'], $this->code, $match, \PREG_OFFSET_CAPTURE, $this->cursor)) {
  453.             throw new SyntaxError('Unexpected end of file: Unclosed "verbatim" block.', $this->lineno, $this->source);
  454.         }
  456.         $text = substr($this->code, $this->cursor, $match[0][1] - $this->cursor);
  457.         $this->moveCursor($text.$match[0][0]);
  459.         // trim?
  460.         if (isset($match[1][0])) {
  461.             if ($this->options['whitespace_trim'] === $match[1][0]) {
  462.                 // whitespace_trim detected ({%-, {{- or {#-)
  463.                 $text = rtrim($text);
  464.             } else {
  465.                 // whitespace_line_trim detected ({%~, {{~ or {#~)
  466.                 // don't trim \r and \n
  467.                 $text = rtrim($text, " \t\0\x0B");
  468.             }
  469.         }
  471.         $this->pushToken(Token::TEXT_TYPE, $text);
  472.     }
  474.     private function lexComment(): void
  475.     {
  476.         if (!preg_match($this->regexes['lex_comment'], $this->code, $match, \PREG_OFFSET_CAPTURE, $this->cursor)) {
  477.             throw new SyntaxError('Unclosed comment.', $this->lineno, $this->source);
  478.         }
  480.         $this->moveCursor(substr($this->code, $this->cursor, $match[0][1] - $this->cursor).$match[0][0]);
  481.     }
  483.     private function lexString(): void
  484.     {
  485.         if (preg_match($this->regexes['interpolation_start'], $this->code, $match, 0, $this->cursor)) {
  486.             $this->brackets[] = [$this->options['interpolation'][0], $this->lineno];
  487.             $this->pushToken(Token::INTERPOLATION_START_TYPE);
  488.             $this->moveCursor($match[0]);
  489.             $this->pushState(self::STATE_INTERPOLATION);
  490.         } elseif (preg_match(self::REGEX_DQ_STRING_PART, $this->code, $match, 0, $this->cursor) && '' !== $match[0]) {
  491.             $this->pushToken(Token::STRING_TYPE, $this->stripcslashes($match[0], '"'));
  492.             $this->moveCursor($match[0]);
  493.         } elseif (preg_match(self::REGEX_DQ_STRING_DELIM, $this->code, $match, 0, $this->cursor)) {
  494.             [$expect, $lineno] = array_pop($this->brackets);
  495.             if ('"' != $this->code[$this->cursor]) {
  496.                 throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
  497.             }
  499.             $this->popState();
  500.             ++$this->cursor;
  501.         } else {
  502.             // unlexable
  503.             throw new SyntaxError(\sprintf('Unexpected character "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
  504.         }
  505.     }
  507.     private function lexInterpolation(): void
  508.     {
  509.         $bracket = end($this->brackets);
  510.         if ($this->options['interpolation'][0] === $bracket[0] && preg_match($this->regexes['interpolation_end'], $this->code, $match, 0, $this->cursor)) {
  511.             array_pop($this->brackets);
  512.             $this->pushToken(Token::INTERPOLATION_END_TYPE);
  513.             $this->moveCursor($match[0]);
  514.             $this->popState();
  515.         } else {
  516.             $this->lexExpression();
  517.         }
  518.     }
  520.     private function pushToken($type, $value = ''): void
  521.     {
  522.         // do not push empty text tokens
  523.         if (Token::TEXT_TYPE === $type && '' === $value) {
  524.             return;
  525.         }
  527.         $this->tokens[] = new Token($type, $value, $this->lineno);
  528.     }
  530.     private function moveCursor($text): void
  531.     {
  532.         $this->cursor += \strlen($text);
  533.         $this->lineno += substr_count($text, "\n");
  534.     }
  536.     private function getOperatorRegex(): string
  537.     {
  538.         $operators = array_merge(
  539.             ['='],
  540.             array_keys($this->env->getUnaryOperators()),
  541.             array_keys($this->env->getBinaryOperators())
  542.         );
  544.         $operators = array_combine($operators, array_map('strlen', $operators));
  545.         arsort($operators);
  547.         $regex = [];
  548.         foreach ($operators as $operator => $length) {
  549.             // an operator that ends with a character must be followed by
  550.             // a whitespace, a parenthesis, an opening map [ or sequence {
  551.             $r = preg_quote($operator, '/');
  552.             if (ctype_alpha($operator[$length - 1])) {
  553.                 $r .= '(?=[\s()\[{])';
  554.             }
  556.             // an operator that begins with a character must not have a dot or pipe before
  557.             if (ctype_alpha($operator[0])) {
  558.                 $r = '(?<![\.\|])'.$r;
  559.             }
  561.             // an operator with a space can be any amount of whitespaces
  562.             $r = preg_replace('/\s+/', '\s+', $r);
  564.             $regex[] = $r;
  565.         }
  567.         return '/'.implode('|', $regex).'/A';
  568.     }
  570.     private function pushState($state): void
  571.     {
  572.         $this->states[] = $this->state;
  573.         $this->state = $state;
  574.     }
  576.     private function popState(): void
  577.     {
  578.         if (0 === \count($this->states)) {
  579.             throw new \LogicException('Cannot pop state without a previous state.');
  580.         }
  582.         $this->state = array_pop($this->states);
  583.     }
  584. }