<?php

/**
 * Validates contents based on NMTOKENS attribute type.
 */
class HTMLPurifier_AttrDef_HTML_Nmtokens extends HTMLPurifier_AttrDef {
	
	/**
	 *
	 * @param string $string        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return bool|string
	 */
	public function validate($string, $config, $context) {
		$string = trim ( $string );
		
		// early abort: '' and '0' (strings that convert to false) are invalid
		if (! $string) {
			return false;
		}
		
		$tokens = $this->split ( $string, $config, $context );
		$tokens = $this->filter ( $tokens, $config, $context );
		if (empty ( $tokens )) {
			return false;
		}
		return implode ( ' ', $tokens );
	}
	
	/**
	 * Splits a space separated list of tokens into its constituent parts.
	 * 
	 * @param string $string        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return array
	 */
	protected function split($string, $config, $context) {
		// OPTIMIZABLE!
		// do the preg_match, capture all subpatterns for reformulation
		
		// we don't support U+00A1 and up codepoints or
		// escaping because I don't know how to do that with regexps
		// and plus it would complicate optimization efforts (you never
		// see that anyway).
		$pattern = '/(?:(?<=\s)|\A)' . // look behind for space or string start
'((?:--|-?[A-Za-z_])[A-Za-z_\-0-9]*)' . '(?:(?=\s)|\z)/'; // look ahead for space or string end
		preg_match_all ( $pattern, $string, $matches );
		return $matches [1];
	}
	
	/**
	 * Template method for removing certain tokens based on arbitrary criteria.
	 * @note If we wanted to be really functional, we'd do an array_filter
	 * with a callback. But... we're not.
	 * 
	 * @param array $tokens        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return array
	 */
	protected function filter($tokens, $config, $context) {
		return $tokens;
	}
}

// vim: et sw=4 sts=4