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- <?php
- declare(strict_types=1);
- namespace Doctrine\Common\Lexer;
- use ReflectionClass;
- use function implode;
- use function in_array;
- use function preg_split;
- use function sprintf;
- use function substr;
- use const PREG_SPLIT_DELIM_CAPTURE;
- use const PREG_SPLIT_NO_EMPTY;
- use const PREG_SPLIT_OFFSET_CAPTURE;
- /**
- * Base class for writing simple lexers, i.e. for creating small DSLs.
- */
- abstract class AbstractLexer
- {
- /**
- * Lexer original input string.
- *
- * @var string
- */
- private $input;
- /**
- * Array of scanned tokens.
- *
- * Each token is an associative array containing three items:
- * - 'value' : the string value of the token in the input string
- * - 'type' : the type of the token (identifier, numeric, string, input
- * parameter, none)
- * - 'position' : the position of the token in the input string
- *
- * @var mixed[][]
- * @psalm-var list<array{value: string, type: string|int|null, position: int}>
- */
- private $tokens = [];
- /**
- * Current lexer position in input string.
- *
- * @var int
- */
- private $position = 0;
- /**
- * Current peek of current lexer position.
- *
- * @var int
- */
- private $peek = 0;
- /**
- * The next token in the input.
- *
- * @var mixed[]|null
- * @psalm-var array{value: string, type: string|int|null, position: int}|null
- */
- public $lookahead;
- /**
- * The last matched/seen token.
- *
- * @var mixed[]|null
- * @psalm-var array{value: string, type: string|int|null, position: int}|null
- */
- public $token;
- /**
- * Composed regex for input parsing.
- *
- * @var string|null
- */
- private $regex;
- /**
- * Sets the input data to be tokenized.
- *
- * The Lexer is immediately reset and the new input tokenized.
- * Any unprocessed tokens from any previous input are lost.
- *
- * @param string $input The input to be tokenized.
- *
- * @return void
- */
- public function setInput($input)
- {
- $this->input = $input;
- $this->tokens = [];
- $this->reset();
- $this->scan($input);
- }
- /**
- * Resets the lexer.
- *
- * @return void
- */
- public function reset()
- {
- $this->lookahead = null;
- $this->token = null;
- $this->peek = 0;
- $this->position = 0;
- }
- /**
- * Resets the peek pointer to 0.
- *
- * @return void
- */
- public function resetPeek()
- {
- $this->peek = 0;
- }
- /**
- * Resets the lexer position on the input to the given position.
- *
- * @param int $position Position to place the lexical scanner.
- *
- * @return void
- */
- public function resetPosition($position = 0)
- {
- $this->position = $position;
- }
- /**
- * Retrieve the original lexer's input until a given position.
- *
- * @param int $position
- *
- * @return string
- */
- public function getInputUntilPosition($position)
- {
- return substr($this->input, 0, $position);
- }
- /**
- * Checks whether a given token matches the current lookahead.
- *
- * @param int|string $token
- *
- * @return bool
- */
- public function isNextToken($token)
- {
- return $this->lookahead !== null && $this->lookahead['type'] === $token;
- }
- /**
- * Checks whether any of the given tokens matches the current lookahead.
- *
- * @param string[] $tokens
- *
- * @return bool
- */
- public function isNextTokenAny(array $tokens)
- {
- return $this->lookahead !== null && in_array($this->lookahead['type'], $tokens, true);
- }
- /**
- * Moves to the next token in the input string.
- *
- * @return bool
- */
- public function moveNext()
- {
- $this->peek = 0;
- $this->token = $this->lookahead;
- $this->lookahead = isset($this->tokens[$this->position])
- ? $this->tokens[$this->position++] : null;
- return $this->lookahead !== null;
- }
- /**
- * Tells the lexer to skip input tokens until it sees a token with the given value.
- *
- * @param string $type The token type to skip until.
- *
- * @return void
- */
- public function skipUntil($type)
- {
- while ($this->lookahead !== null && $this->lookahead['type'] !== $type) {
- $this->moveNext();
- }
- }
- /**
- * Checks if given value is identical to the given token.
- *
- * @param mixed $value
- * @param int|string $token
- *
- * @return bool
- */
- public function isA($value, $token)
- {
- return $this->getType($value) === $token;
- }
- /**
- * Moves the lookahead token forward.
- *
- * @return mixed[]|null The next token or NULL if there are no more tokens ahead.
- * @psalm-return array{value: string, type: string|int|null, position: int}|null
- */
- public function peek()
- {
- if (isset($this->tokens[$this->position + $this->peek])) {
- return $this->tokens[$this->position + $this->peek++];
- }
- return null;
- }
- /**
- * Peeks at the next token, returns it and immediately resets the peek.
- *
- * @return mixed[]|null The next token or NULL if there are no more tokens ahead.
- * @psalm-return array{value: string, type: string|int|null, position: int}|null
- */
- public function glimpse()
- {
- $peek = $this->peek();
- $this->peek = 0;
- return $peek;
- }
- /**
- * Scans the input string for tokens.
- *
- * @param string $input A query string.
- *
- * @return void
- */
- protected function scan($input)
- {
- if (! isset($this->regex)) {
- $this->regex = sprintf(
- '/(%s)|%s/%s',
- implode(')|(', $this->getCatchablePatterns()),
- implode('|', $this->getNonCatchablePatterns()),
- $this->getModifiers()
- );
- }
- $flags = PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_OFFSET_CAPTURE;
- $matches = preg_split($this->regex, $input, -1, $flags);
- if ($matches === false) {
- // Work around https://bugs.php.net/78122
- $matches = [[$input, 0]];
- }
- foreach ($matches as $match) {
- // Must remain before 'value' assignment since it can change content
- $type = $this->getType($match[0]);
- $this->tokens[] = [
- 'value' => $match[0],
- 'type' => $type,
- 'position' => $match[1],
- ];
- }
- }
- /**
- * Gets the literal for a given token.
- *
- * @param int|string $token
- *
- * @return int|string
- */
- public function getLiteral($token)
- {
- $className = static::class;
- $reflClass = new ReflectionClass($className);
- $constants = $reflClass->getConstants();
- foreach ($constants as $name => $value) {
- if ($value === $token) {
- return $className . '::' . $name;
- }
- }
- return $token;
- }
- /**
- * Regex modifiers
- *
- * @return string
- */
- protected function getModifiers()
- {
- return 'iu';
- }
- /**
- * Lexical catchable patterns.
- *
- * @return string[]
- */
- abstract protected function getCatchablePatterns();
- /**
- * Lexical non-catchable patterns.
- *
- * @return string[]
- */
- abstract protected function getNonCatchablePatterns();
- /**
- * Retrieve token type. Also processes the token value if necessary.
- *
- * @param string $value
- *
- * @return int|string|null
- */
- abstract protected function getType(&$value);
- }
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