Lexer.php

<?php


/*
 * This file is part of Twig.
 *
 * (c) Fabien Potencier
 * (c) Armin Ronacher
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Twig;

use Twig\Error\SyntaxError;

/**
 * @author Fabien Potencier <fabien@symfony.com>
 */
class Lexer {
    private $isInitialized = false;
    private $tokens;
    private $code;
    private $cursor;
    private $lineno;
    private $end;
    private $state;
    private $states;
    private $brackets;
    private $env;
    private $source;
    private $options;
    private $regexes;
    private $position;
    private $positions;
    private $currentVarBlockLine;
    public const STATE_DATA = 0;
    public const STATE_BLOCK = 1;
    public const STATE_VAR = 2;
    public const STATE_STRING = 3;
    public const STATE_INTERPOLATION = 4;
    public const REGEX_NAME = '/[a-zA-Z_\\x7f-\\xff][a-zA-Z0-9_\\x7f-\\xff]*/A';
    public const REGEX_NUMBER = '/[0-9]+(?:\\.[0-9]+)?([Ee][\\+\\-][0-9]+)?/A';
    public const REGEX_STRING = '/"([^#"\\\\]*(?:\\\\.[^#"\\\\]*)*)"|\'([^\'\\\\]*(?:\\\\.[^\'\\\\]*)*)\'/As';
    public const REGEX_DQ_STRING_DELIM = '/"/A';
    public const REGEX_DQ_STRING_PART = '/[^#"\\\\]*(?:(?:\\\\.|#(?!\\{))[^#"\\\\]*)*/As';
    public const REGEX_INLINE_COMMENT = '/#[^\\n]*/A';
    public const PUNCTUATION = '()[]{}?:.,|';
    private const SPECIAL_CHARS = [
        'f' => "\f",
        'n' => "\n",
        'r' => "\r",
        't' => "\t",
        'v' => "\v",
    ];
    public function __construct(Environment $env, array $options = []) {
        $this->env = $env;
        $this->options = array_merge([
            'tag_comment' => [
                '{#',
                '#}',
            ],
            'tag_block' => [
                '{%',
                '%}',
            ],
            'tag_variable' => [
                '{{',
                '}}',
            ],
            'whitespace_trim' => '-',
            'whitespace_line_trim' => '~',
            'whitespace_line_chars' => ' \\t\\0\\x0B',
            'interpolation' => [
                '#{',
                '}',
            ],
        ], $options);
    }
    private function initialize() {
        if ($this->isInitialized) {
            return;
        }
        // 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
        $this->regexes = [
            // }}
'lex_var' => '{
                \\s*
                (?:' . preg_quote($this->options['whitespace_trim'] . $this->options['tag_variable'][1], '#') . '\\s*' . '|' . preg_quote($this->options['whitespace_line_trim'] . $this->options['tag_variable'][1], '#') . '[' . $this->options['whitespace_line_chars'] . ']*' . '|' . preg_quote($this->options['tag_variable'][1], '#') . ')
            }Ax',
            // %}
'lex_block' => '{
                \\s*
                (?:' . preg_quote($this->options['whitespace_trim'] . $this->options['tag_block'][1], '#') . '\\s*\\n?' . '|' . preg_quote($this->options['whitespace_line_trim'] . $this->options['tag_block'][1], '#') . '[' . $this->options['whitespace_line_chars'] . ']*' . '|' . preg_quote($this->options['tag_block'][1], '#') . '\\n?' . ')
            }Ax',
            // {% endverbatim %}
'lex_raw_data' => '{' . preg_quote($this->options['tag_block'][0], '#') . '(' . $this->options['whitespace_trim'] . '|' . $this->options['whitespace_line_trim'] . ')?\\s*endverbatim\\s*' . '(?:' . preg_quote($this->options['whitespace_trim'] . $this->options['tag_block'][1], '#') . '\\s*' . '|' . preg_quote($this->options['whitespace_line_trim'] . $this->options['tag_block'][1], '#') . '[' . $this->options['whitespace_line_chars'] . ']*' . '|' . preg_quote($this->options['tag_block'][1], '#') . ')
            }sx',
            'operator' => $this->getOperatorRegex(),
            // #}
'lex_comment' => '{
                (?:' . preg_quote($this->options['whitespace_trim'] . $this->options['tag_comment'][1], '#') . '\\s*\\n?' . '|' . preg_quote($this->options['whitespace_line_trim'] . $this->options['tag_comment'][1], '#') . '[' . $this->options['whitespace_line_chars'] . ']*' . '|' . preg_quote($this->options['tag_comment'][1], '#') . '\\n?' . ')
            }sx',
            // verbatim %}
'lex_block_raw' => '{
                \\s*verbatim\\s*
                (?:' . preg_quote($this->options['whitespace_trim'] . $this->options['tag_block'][1], '#') . '\\s*' . '|' . preg_quote($this->options['whitespace_line_trim'] . $this->options['tag_block'][1], '#') . '[' . $this->options['whitespace_line_chars'] . ']*' . '|' . preg_quote($this->options['tag_block'][1], '#') . ')
            }Asx',
            'lex_block_line' => '{\\s*line\\s+(\\d+)\\s*' . preg_quote($this->options['tag_block'][1], '#') . '}As',
            // {{ or {% or {#
'lex_tokens_start' => '{
                (' . preg_quote($this->options['tag_variable'][0], '#') . '|' . preg_quote($this->options['tag_block'][0], '#') . '|' . preg_quote($this->options['tag_comment'][0], '#') . ')(' . preg_quote($this->options['whitespace_trim'], '#') . '|' . preg_quote($this->options['whitespace_line_trim'], '#') . ')?
            }sx',
            'interpolation_start' => '{' . preg_quote($this->options['interpolation'][0], '#') . '\\s*}A',
            'interpolation_end' => '{\\s*' . preg_quote($this->options['interpolation'][1], '#') . '}A',
        ];
        $this->isInitialized = true;
    }
    public function tokenize(Source $source) : TokenStream {
        $this->initialize();
        $this->source = $source;
        $this->code = str_replace([
            "\r\n",
            "\r",
        ], "\n", $source->getCode());
        $this->cursor = 0;
        $this->lineno = 1;
        $this->end = \strlen($this->code);
        $this->tokens = [];
        $this->state = self::STATE_DATA;
        $this->states = [];
        $this->brackets = [];
        $this->position = -1;
        // find all token starts in one go
        preg_match_all($this->regexes['lex_tokens_start'], $this->code, $matches, \PREG_OFFSET_CAPTURE);
        $this->positions = $matches;
        while ($this->cursor < $this->end) {
            // dispatch to the lexing functions depending
            // on the current state
            switch ($this->state) {
                case self::STATE_DATA:
                    $this->lexData();
                    break;
                case self::STATE_BLOCK:
                    $this->lexBlock();
                    break;
                case self::STATE_VAR:
                    $this->lexVar();
                    break;
                case self::STATE_STRING:
                    $this->lexString();
                    break;
                case self::STATE_INTERPOLATION:
                    $this->lexInterpolation();
                    break;
            }
        }
        $this->pushToken(Token::EOF_TYPE);
        if ($this->brackets) {
            [
                $expect,
                $lineno,
            ] = array_pop($this->brackets);
            throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
        }
        return new TokenStream($this->tokens, $this->source);
    }
    private function lexData() : void {
        // if no matches are left we return the rest of the template as simple text token
        if ($this->position == \count($this->positions[0]) - 1) {
            $this->pushToken(Token::TEXT_TYPE, substr($this->code, $this->cursor));
            $this->cursor = $this->end;
            return;
        }
        // Find the first token after the current cursor
        $position = $this->positions[0][++$this->position];
        while ($position[1] < $this->cursor) {
            if ($this->position == \count($this->positions[0]) - 1) {
                return;
            }
            $position = $this->positions[0][++$this->position];
        }
        // push the template text first
        $text = $textContent = substr($this->code, $this->cursor, $position[1] - $this->cursor);
        // trim?
        if (isset($this->positions[2][$this->position][0])) {
            if ($this->options['whitespace_trim'] === $this->positions[2][$this->position][0]) {
                // whitespace_trim detected ({%-, {{- or {#-)
                $text = rtrim($text);
            }
            elseif ($this->options['whitespace_line_trim'] === $this->positions[2][$this->position][0]) {
                // whitespace_line_trim detected ({%~, {{~ or {#~)
                // don't trim \r and \n
                $text = rtrim($text, " \t\x00\v");
            }
        }
        $this->pushToken(Token::TEXT_TYPE, $text);
        $this->moveCursor($textContent . $position[0]);
        switch ($this->positions[1][$this->position][0]) {
            case $this->options['tag_comment'][0]:
                $this->lexComment();
                break;
            case $this->options['tag_block'][0]:
                // raw data?
                if (preg_match($this->regexes['lex_block_raw'], $this->code, $match, 0, $this->cursor)) {
                    $this->moveCursor($match[0]);
                    $this->lexRawData();
                    // {% line \d+ %}
                }
                elseif (preg_match($this->regexes['lex_block_line'], $this->code, $match, 0, $this->cursor)) {
                    $this->moveCursor($match[0]);
                    $this->lineno = (int) $match[1];
                }
                else {
                    $this->pushToken(Token::BLOCK_START_TYPE);
                    $this->pushState(self::STATE_BLOCK);
                    $this->currentVarBlockLine = $this->lineno;
                }
                break;
            case $this->options['tag_variable'][0]:
                $this->pushToken(Token::VAR_START_TYPE);
                $this->pushState(self::STATE_VAR);
                $this->currentVarBlockLine = $this->lineno;
                break;
        }
    }
    private function lexBlock() : void {
        if (!$this->brackets && preg_match($this->regexes['lex_block'], $this->code, $match, 0, $this->cursor)) {
            $this->pushToken(Token::BLOCK_END_TYPE);
            $this->moveCursor($match[0]);
            $this->popState();
        }
        else {
            $this->lexExpression();
        }
    }
    private function lexVar() : void {
        if (!$this->brackets && preg_match($this->regexes['lex_var'], $this->code, $match, 0, $this->cursor)) {
            $this->pushToken(Token::VAR_END_TYPE);
            $this->moveCursor($match[0]);
            $this->popState();
        }
        else {
            $this->lexExpression();
        }
    }
    private function lexExpression() : void {
        // whitespace
        if (preg_match('/\\s+/A', $this->code, $match, 0, $this->cursor)) {
            $this->moveCursor($match[0]);
            if ($this->cursor >= $this->end) {
                throw new SyntaxError(\sprintf('Unclosed "%s".', self::STATE_BLOCK === $this->state ? 'block' : 'variable'), $this->currentVarBlockLine, $this->source);
            }
        }
        // spread operator
        if ('.' === $this->code[$this->cursor] && $this->cursor + 2 < $this->end && '.' === $this->code[$this->cursor + 1] && '.' === $this->code[$this->cursor + 2]) {
            $this->pushToken(Token::SPREAD_TYPE, '...');
            $this->moveCursor('...');
        }
        elseif ('=' === $this->code[$this->cursor] && $this->cursor + 1 < $this->end && '>' === $this->code[$this->cursor + 1]) {
            $this->pushToken(Token::ARROW_TYPE, '=>');
            $this->moveCursor('=>');
        }
        elseif (preg_match($this->regexes['operator'], $this->code, $match, 0, $this->cursor)) {
            $this->pushToken(Token::OPERATOR_TYPE, preg_replace('/\\s+/', ' ', $match[0]));
            $this->moveCursor($match[0]);
        }
        elseif (preg_match(self::REGEX_NAME, $this->code, $match, 0, $this->cursor)) {
            $this->pushToken(Token::NAME_TYPE, $match[0]);
            $this->moveCursor($match[0]);
        }
        elseif (preg_match(self::REGEX_NUMBER, $this->code, $match, 0, $this->cursor)) {
            $number = (double) $match[0];
            // floats
            if (ctype_digit($match[0]) && $number <= \PHP_INT_MAX) {
                $number = (int) $match[0];
                // integers lower than the maximum
            }
            $this->pushToken(Token::NUMBER_TYPE, $number);
            $this->moveCursor($match[0]);
        }
        elseif (str_contains(self::PUNCTUATION, $this->code[$this->cursor])) {
            // opening bracket
            if (str_contains('([{', $this->code[$this->cursor])) {
                $this->brackets[] = [
                    $this->code[$this->cursor],
                    $this->lineno,
                ];
            }
            elseif (str_contains(')]}', $this->code[$this->cursor])) {
                if (!$this->brackets) {
                    throw new SyntaxError(\sprintf('Unexpected "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
                }
                [
                    $expect,
                    $lineno,
                ] = array_pop($this->brackets);
                if ($this->code[$this->cursor] != strtr($expect, '([{', ')]}')) {
                    throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
                }
            }
            $this->pushToken(Token::PUNCTUATION_TYPE, $this->code[$this->cursor]);
            ++$this->cursor;
        }
        elseif (preg_match(self::REGEX_STRING, $this->code, $match, 0, $this->cursor)) {
            $this->pushToken(Token::STRING_TYPE, $this->stripcslashes(substr($match[0], 1, -1), substr($match[0], 0, 1)));
            $this->moveCursor($match[0]);
        }
        elseif (preg_match(self::REGEX_DQ_STRING_DELIM, $this->code, $match, 0, $this->cursor)) {
            $this->brackets[] = [
                '"',
                $this->lineno,
            ];
            $this->pushState(self::STATE_STRING);
            $this->moveCursor($match[0]);
        }
        elseif (preg_match(self::REGEX_INLINE_COMMENT, $this->code, $match, 0, $this->cursor)) {
            $this->moveCursor($match[0]);
        }
        else {
            throw new SyntaxError(\sprintf('Unexpected character "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
        }
    }
    private function stripcslashes(string $str, string $quoteType) : string {
        $result = '';
        $length = \strlen($str);
        $i = 0;
        while ($i < $length) {
            if (false === ($pos = strpos($str, '\\', $i))) {
                $result .= substr($str, $i);
                break;
            }
            $result .= substr($str, $i, $pos - $i);
            $i = $pos + 1;
            if ($i >= $length) {
                $result .= '\\';
                break;
            }
            $nextChar = $str[$i];
            if (isset(self::SPECIAL_CHARS[$nextChar])) {
                $result .= self::SPECIAL_CHARS[$nextChar];
            }
            elseif ('\\' === $nextChar) {
                $result .= $nextChar;
            }
            elseif ("'" === $nextChar || '"' === $nextChar) {
                if ($nextChar !== $quoteType) {
                    trigger_deprecation('twig/twig', '3.12', 'Character "%s" should not be escaped; the "\\" character is ignored in Twig 3 but will not be in Twig 4. Please remove the extra "\\" character at position %d in "%s" at line %d.', $nextChar, $i + 1, $this->source
                        ->getName(), $this->lineno);
                }
                $result .= $nextChar;
            }
            elseif ('#' === $nextChar && $i + 1 < $length && '{' === $str[$i + 1]) {
                $result .= '#{';
                ++$i;
            }
            elseif ('x' === $nextChar && $i + 1 < $length && ctype_xdigit($str[$i + 1])) {
                $hex = $str[++$i];
                if ($i + 1 < $length && ctype_xdigit($str[$i + 1])) {
                    $hex .= $str[++$i];
                }
                $result .= \chr(hexdec($hex));
            }
            elseif (ctype_digit($nextChar) && $nextChar < '8') {
                $octal = $nextChar;
                while ($i + 1 < $length && ctype_digit($str[$i + 1]) && $str[$i + 1] < '8' && \strlen($octal) < 3) {
                    $octal .= $str[++$i];
                }
                $result .= \chr(octdec($octal));
            }
            else {
                trigger_deprecation('twig/twig', '3.12', 'Character "%s" should not be escaped; the "\\" character is ignored in Twig 3 but will not be in Twig 4. Please remove the extra "\\" character at position %d in "%s" at line %d.', $nextChar, $i + 1, $this->source
                    ->getName(), $this->lineno);
                $result .= $nextChar;
            }
            ++$i;
        }
        return $result;
    }
    private function lexRawData() : void {
        if (!preg_match($this->regexes['lex_raw_data'], $this->code, $match, \PREG_OFFSET_CAPTURE, $this->cursor)) {
            throw new SyntaxError('Unexpected end of file: Unclosed "verbatim" block.', $this->lineno, $this->source);
        }
        $text = substr($this->code, $this->cursor, $match[0][1] - $this->cursor);
        $this->moveCursor($text . $match[0][0]);
        // trim?
        if (isset($match[1][0])) {
            if ($this->options['whitespace_trim'] === $match[1][0]) {
                // whitespace_trim detected ({%-, {{- or {#-)
                $text = rtrim($text);
            }
            else {
                // whitespace_line_trim detected ({%~, {{~ or {#~)
                // don't trim \r and \n
                $text = rtrim($text, " \t\x00\v");
            }
        }
        $this->pushToken(Token::TEXT_TYPE, $text);
    }
    private function lexComment() : void {
        if (!preg_match($this->regexes['lex_comment'], $this->code, $match, \PREG_OFFSET_CAPTURE, $this->cursor)) {
            throw new SyntaxError('Unclosed comment.', $this->lineno, $this->source);
        }
        $this->moveCursor(substr($this->code, $this->cursor, $match[0][1] - $this->cursor) . $match[0][0]);
    }
    private function lexString() : void {
        if (preg_match($this->regexes['interpolation_start'], $this->code, $match, 0, $this->cursor)) {
            $this->brackets[] = [
                $this->options['interpolation'][0],
                $this->lineno,
            ];
            $this->pushToken(Token::INTERPOLATION_START_TYPE);
            $this->moveCursor($match[0]);
            $this->pushState(self::STATE_INTERPOLATION);
        }
        elseif (preg_match(self::REGEX_DQ_STRING_PART, $this->code, $match, 0, $this->cursor) && '' !== $match[0]) {
            $this->pushToken(Token::STRING_TYPE, $this->stripcslashes($match[0], '"'));
            $this->moveCursor($match[0]);
        }
        elseif (preg_match(self::REGEX_DQ_STRING_DELIM, $this->code, $match, 0, $this->cursor)) {
            [
                $expect,
                $lineno,
            ] = array_pop($this->brackets);
            if ('"' != $this->code[$this->cursor]) {
                throw new SyntaxError(\sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
            }
            $this->popState();
            ++$this->cursor;
        }
        else {
            // unlexable
            throw new SyntaxError(\sprintf('Unexpected character "%s".', $this->code[$this->cursor]), $this->lineno, $this->source);
        }
    }
    private function lexInterpolation() : void {
        $bracket = end($this->brackets);
        if ($this->options['interpolation'][0] === $bracket[0] && preg_match($this->regexes['interpolation_end'], $this->code, $match, 0, $this->cursor)) {
            array_pop($this->brackets);
            $this->pushToken(Token::INTERPOLATION_END_TYPE);
            $this->moveCursor($match[0]);
            $this->popState();
        }
        else {
            $this->lexExpression();
        }
    }
    private function pushToken($type, $value = '') : void {
        // do not push empty text tokens
        if (Token::TEXT_TYPE === $type && '' === $value) {
            return;
        }
        $this->tokens[] = new Token($type, $value, $this->lineno);
    }
    private function moveCursor($text) : void {
        $this->cursor += \strlen($text);
        $this->lineno += substr_count($text, "\n");
    }
    private function getOperatorRegex() : string {
        $operators = array_merge([
            '=',
        ], array_keys($this->env
            ->getUnaryOperators()), array_keys($this->env
            ->getBinaryOperators()));
        $operators = array_combine($operators, array_map('strlen', $operators));
        arsort($operators);
        $regex = [];
        foreach ($operators as $operator => $length) {
            // an operator that ends with a character must be followed by
            // a whitespace, a parenthesis, an opening map [ or sequence {
            $r = preg_quote($operator, '/');
            if (ctype_alpha($operator[$length - 1])) {
                $r .= '(?=[\\s()\\[{])';
            }
            // an operator that begins with a character must not have a dot or pipe before
            if (ctype_alpha($operator[0])) {
                $r = '(?<![\\.\\|])' . $r;
            }
            // an operator with a space can be any amount of whitespaces
            $r = preg_replace('/\\s+/', '\\s+', $r);
            $regex[] = $r;
        }
        return '/' . implode('|', $regex) . '/A';
    }
    private function pushState($state) : void {
        $this->states[] = $this->state;
        $this->state = $state;
    }
    private function popState() : void {
        if (0 === \count($this->states)) {
            throw new \LogicException('Cannot pop state without a previous state.');
        }
        $this->state = array_pop($this->states);
    }

}