SassScriptLexer.php in Sassy 7

File

phamlp/sass/script/SassScriptLexer.php

<?php

/* SVN FILE: $Id$ */

/**
 * SassScriptLexer class file.
 * @author			Chris Yates <[e-mail]>
 * @copyright 	Copyright (c) 2010 PBM Web Development
 * @license			http://phamlp.googlecode.com/files/license.txt
 * @package			PHamlP
 * @subpackage	Sass.script
 */
require_once 'literals/SassBoolean.php';
require_once 'literals/SassColour.php';
require_once 'literals/SassNumber.php';
require_once 'literals/SassString.php';
require_once 'SassScriptFunction.php';
require_once 'SassScriptOperation.php';
require_once 'SassScriptVariable.php';

/**
 * SassScriptLexer class.
 * Lexes SassSCript into tokens for the parser.
 * 
 * Implements a {@link http://en.wikipedia.org/wiki/Shunting-yard_algorithm Shunting-yard algorithm} to provide {@link http://en.wikipedia.org/wiki/Reverse_Polish_notation Reverse Polish notation} output.
 * @package			PHamlP
 * @subpackage	Sass.script
 */
class SassScriptLexer {
  const MATCH_WHITESPACE = '/^\\s+/';

  /**
   * @var SassScriptParser the parser object
   */
  private $parser;

  /**
   * SassScriptLexer constructor.
   * @return SassScriptLexer
   */
  public function __construct($parser) {
    $this->parser = $parser;
  }

  /**
   * Lex an expression into SassScript tokens.
   * @param string expression to lex
   * @param SassContext the context in which the expression is lexed
   * @return array tokens
   */
  public function lex($string, $context) {
    $tokens = array();
    while ($string !== false) {
      if (($match = $this
        ->isWhitespace($string)) !== false) {
        $tokens[] = null;
      }
      elseif (($match = SassScriptFunction::isa($string)) !== false) {
        preg_match(SassScriptFunction::MATCH_FUNC, $match, $matches);
        $args = array();
        foreach (SassScriptFunction::extractArgs($matches[SassScriptFunction::ARGS]) as $expression) {
          $args[] = $this->parser
            ->evaluate($expression, $context);
        }
        $tokens[] = new SassScriptFunction($matches[SassScriptFunction::NAME], $args);
      }
      elseif (($match = SassString::isa($string)) !== false) {
        $tokens[] = new SassString($match);
      }
      elseif (($match = SassBoolean::isa($string)) !== false) {
        $tokens[] = new SassBoolean($match);
      }
      elseif (($match = SassColour::isa($string)) !== false) {
        $tokens[] = new SassColour($match);
      }
      elseif (($match = SassNumber::isa($string)) !== false) {
        $tokens[] = new SassNumber($match);
      }
      elseif (($match = SassScriptOperation::isa($string)) !== false) {
        $tokens[] = new SassScriptOperation($match);
      }
      elseif (($match = SassScriptVariable::isa($string)) !== false) {
        $tokens[] = new SassScriptVariable($match);
      }
      else {
        $_string = $string;
        $match = '';
        while (strlen($_string) && !$this
          ->isWhitespace($_string)) {
          foreach (SassScriptOperation::$inStrOperators as $operator) {
            if (substr($_string, 0, strlen($operator)) == $operator) {
              break 2;
            }
          }
          $match .= $_string[0];
          $_string = substr($_string, 1);
        }
        $tokens[] = new SassString($match);
      }
      $string = substr($string, strlen($match));
    }
    return $tokens;
  }

  /**
   * Returns a value indicating if a token of this type can be matched at
   * the start of the subject string.
   * @param string the subject string
   * @return mixed match at the start of the string or false if no match
   */
  public function isWhitespace($subject) {
    return preg_match(self::MATCH_WHITESPACE, $subject, $matches) ? $matches[0] : false;
  }

}

Classes

Name	Description
SassScriptLexer	SassScriptLexer class. Lexes SassSCript into tokens for the parser.