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Lexer.php
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Lexer.php
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<?php
declare(strict_types=1);
namespace Neos\Fusion\Afx\Parser;
/*
* This file is part of the Neos.Fusion.Afx package.
*
* (c) Contributors of the Neos Project - www.neos.io
*
* This package is Open Source Software. For the full copyright and license
* information, please view the LICENSE file which was distributed with this
* source code.
*/
/**
* A primitive lexer that recognizes Afx-specific characters while iterating
* through a string
* @package Neos\Fusion\Afx\Parser
*/
class Lexer
{
/**
* The string to be iterated through
*
* @var string
*/
protected $string;
/**
* The currently focused character
*
* @var string
*/
protected $currentCharacter;
/**
* The current character position
*
* @var integer
*/
protected $characterPosition;
/**
* Constructor
*
* @param string $string
*/
public function __construct($string)
{
$this->string = $string;
$this->currentCharacter = ($string !== '') ? $string[0] : null;
$this->characterPosition = 0;
}
/**
* Checks if the current character is whitespace
*
* @return boolean
*/
public function isWhiteSpace(): bool
{
return ctype_space($this->currentCharacter);
}
/**
* Checks if the current character is a letter
*
* @return boolean
*/
public function isAlpha(): bool
{
return ctype_alpha($this->currentCharacter);
}
/**
* Checks if the current character is alpha-numeric
*
* @return boolean
*/
public function isAlphaNumeric(): bool
{
return ctype_alnum($this->currentCharacter);
}
/**
* Checks if the current character is a colon
*
* @return boolean
*/
public function isColon(): bool
{
return $this->currentCharacter === ':';
}
/**
* Checks if the current character is a dot
*
* @return boolean
*/
public function isDot(): bool
{
return $this->currentCharacter === '.';
}
/**
* Checks if the current character is a @
*
* @return boolean
*/
public function isAt(): bool
{
return $this->currentCharacter === '@';
}
/**
* Checks if the current character is a minus
*
* @return boolean
*/
public function isMinus(): bool
{
return $this->currentCharacter === '-';
}
/**
* Checks if the current character is an underscore
*
* @return boolean
*/
public function isUnderscore(): bool
{
return $this->currentCharacter === '_';
}
/**
* Checks if the current character is an equal sign
*
* @return boolean
*/
public function isEqualSign(): bool
{
return $this->currentCharacter === '=';
}
/**
* Checks if the current character is an opening bracket
*
* @return boolean
*/
public function isOpeningBracket(): bool
{
return $this->currentCharacter === '<';
}
/**
* Checks if the current character is a closing bracket
*
* @return boolean
*/
public function isClosingBracket(): bool
{
return $this->currentCharacter === '>';
}
/**
* Checks if the current character is an opening curly brace
*
* @return boolean
*/
public function isOpeningBrace(): bool
{
return $this->currentCharacter === '{';
}
/**
* Checks if the current character is a closing curly brace
*
* @return boolean
*/
public function isClosingBrace(): bool
{
return $this->currentCharacter === '}';
}
/**
* Checks if the current character is a forward slash
*
* @return boolean
*/
public function isForwardSlash(): bool
{
return $this->currentCharacter === '/';
}
/**
* Checks if the current character is a back slash
*
* @return boolean
*/
public function isBackSlash(): bool
{
return $this->currentCharacter === '\\';
}
/**
* Checks if the current character is a single quote
*
* @return boolean
*/
public function isSingleQuote(): bool
{
return $this->currentCharacter === '\'';
}
/**
* Checks if the current character is a double quote
*
* @return boolean
*/
public function isDoubleQuote(): bool
{
return $this->currentCharacter === '"';
}
/**
* Checks if the current character is an exclamation mark
*
* @return boolean
*/
public function isExclamationMark(): bool
{
return $this->currentCharacter === '!';
}
/**
* Checks if the iteration has ended
*
* @return boolean
*/
public function isEnd(): bool
{
return $this->currentCharacter === null;
}
/**
* Rewinds the iteration by one step
*
* @return void
*/
public function rewind(): void
{
$this->currentCharacter = $this->string[--$this->characterPosition];
}
/**
* Peek several characters in advance and return the next n characters
*
* @param int $characterNumber
* @return string|null
*/
public function peek($characterNumber = 1): ?string
{
if ($this->characterPosition < strlen($this->string) - 1) {
return substr($this->string, $this->characterPosition, $characterNumber);
} else {
return null;
}
}
/**
* Returns the current character and moves one step forward
*
* @return string|null
*/
public function consume(): ?string
{
$c = $this->currentCharacter;
if ($this->characterPosition < strlen($this->string) - 1) {
$this->currentCharacter = $this->string[++$this->characterPosition];
} else {
$this->currentCharacter = null;
}
return $c;
}
}