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plugins/system/nrframework/NRFramework/Parser/Lexer.php

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+<?php
+
+/**
+ *  @author          Tassos.gr <info@tassos.gr>
+ *  @link            https://www.tassos.gr
+ *  @copyright       Copyright © 2024 Tassos All Rights Reserved
+ *  @license         GNU GPLv3 <http://www.gnu.org/licenses/gpl.html> or later
+*/
+
+namespace NRFramework\Parser;
+
+defined('_JEXEC') or die;
+
+use NRFramework\Parser\Tokens;
+
+/**
+ *  Lexer base class
+ * 
+ *  TODO: Rename to Tokenizer??
+ */
+abstract class Lexer
+{
+   /**
+    *  EOF character
+    */
+   const EOF = -1;
+
+   /**
+    *  Tokens instance
+    *
+    *  @var NRFramework\Parser\Tokens
+    */
+   protected $tokens = null;  // Tokens instance
+
+   /**
+    *  Input string
+    *
+    *  @var string
+    */
+   protected $input;
+
+   /**
+    *  Input string length
+    */
+   protected $length;
+
+   /**
+    *  The index of the current character
+    *  in the input string 
+    *
+    * @var integer
+    */
+   protected $index = 0;
+
+   /**
+    *  Current character in input string
+    *
+    *  @var string
+    */
+   protected $cur;
+
+   /**
+    *  A Mark(position) inside the input string.
+    *  Used when matching ahead of the 'current' character
+    *
+    *  @var integer
+    */
+   protected $mark = 0;
+
+   /**
+    *  Holds the Lexer's state
+    *
+    *  @var object
+    */
+   protected $state;
+
+   /**
+    *  Lexer constructor
+    *
+    *  @param string $input
+    */
+   public function __construct($input)
+   {
+       $this->input   = $input;
+       $this->length  = strlen($input);
+       $this->cur     = $this->length >= 1 ? $this->input[0] : Lexer::EOF;
+       $this->tokens  = new Tokens();
+       
+       // inititalize state
+       $this->state                     = new \StdClass();
+       $this->state->skip_whitespace    = true;
+       $this->state->tokenize_content   = true;
+   }
+
+   /**
+    *  Returns the next token from the input string.
+    *
+    *  @return NRFramework\Parser\Token
+    */
+   abstract function nextToken();
+
+   /**
+    *  Moves n characters ahead in the input string.
+    *  Returns all n characters.
+    *  Detects "end of file".
+    * 
+    *  @param  integer $n  Number of characters to advance
+    *  @return string      The n previous characters
+    */
+   public function consume($n = 1)
+   {
+       $prev = '';
+       for ($i=0; $i < $n; $i++)
+       {
+           $prev .= $this->cur;
+           if ( ($this->index + 1) >= $this->length) 
+           {
+               $this->cur = Lexer::EOF;
+               break;
+           }
+           else
+           {
+               $this->index++;
+               $this->cur = $this->input[$this->index];
+           }
+       }
+
+       return $prev;
+   }
+
+   /**
+    *  Sets the skip_whitespce state
+    *
+    *  @param boolean $skip
+    *  @return void
+    */
+   public function setSkipWhitespaceState($skip = true)
+   {
+       $this->state->skip_whitespace = $skip;
+   }
+
+   /**
+    * Sets the tokenize_content state
+    * 
+    * @param bool 
+    * @return void
+    */
+    public function setTokenizeContentState($state = true)
+    {
+        $this->state->tokenize_content = $state;
+    }
+
+    /**
+    * Gets the tokenize_content state
+    * 
+    * @param bool 
+    * @return bool
+    */
+    public function getTokenizeContentState()
+    {
+        return $this->state->tokenize_content;
+    }
+
+   /**
+    *  Marks the current index
+    *
+    *  @return void
+    */
+   public function mark()
+   {
+       $this->mark = $this->index;
+   }
+
+   /**
+    *  Reset index to previously marked position (or at the start of the stream if not marked)
+    *
+    *  @return void
+    */
+   public function reset()
+   {
+       $this->index   = $this->mark;
+       $this->cur     = $this->input[$this->index];
+       $this->mark    = 0;
+   }
+
+   /**
+    *  Get the token types array from the Tokens instance
+    *
+    *  @return void
+    */
+   public function getTokensTypes()
+   {
+       return $this->tokens->getTypes();
+   }
+
+   /**
+    *  Returns the current position in the input stream
+    *
+    *  @return integer
+    */
+   public function getStreamPosition()
+   {
+       return $this->index;
+   }
+
+   /**
+    *  whitespace : (' '|'\t'|'\n'|'\r')
+    *  Ignores any whitespace while advancing
+    *  @return null
+    */
+   protected function whitespace()
+   {
+       while (preg_match('/\s+/', $this->cur)) $this->consume();
+   }
+}