source: branches/HeuristicLab.Problems.GrammaticalOptimization/SharpVectorCss/Css/CssCharsetRule.cs @ 13825

// <developer>niklas@protocol7.com</developer>
// <completed>80</completed>

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace SharpVectors.Dom.Css
{
  /// <summary>
  /// The CSSCharsetRule interface represents a @charset rule in a CSS style sheet. The value of the encoding attribute does not affect the encoding of text data in the DOM objects; this encoding is always UTF-16. After a stylesheet is loaded, the value of the encoding attribute is the value found in the @charset rule. If there was no @charset in the original document, then no CSSCharsetRule is created. The value of the encoding attribute may also be used as a hint for the encoding used on serialization of the style sheet.
  /// The value of the @charset rule (and therefore of the CSSCharsetRule) may not correspond to the encoding the document actually came in; character encoding information e.g. in an HTTP header, has priority (see CSS document representation) but this is not reflected in the CSSCharsetRule.
  /// </summary>
  public class CssCharsetRule : CssRule, ICssCharsetRule
  {
    #region Static members
    private static Regex regex = new Regex(@"^@charset\s""(?<charsetencoding>[^""]+)"";");

        internal static CssRule Parse(ref string css, object parent, bool readOnly, IList<string> replacedStrings, CssStyleSheetType origin)
    {
      Match match = regex.Match(css);
      if(match.Success)
      {
        CssCharsetRule rule = new CssCharsetRule(match, parent, readOnly, replacedStrings, origin);
        css = css.Substring(match.Length);
        return rule;
      }
      else
      {
        // didn't match => do nothing
        return null;
      }
    }
    #endregion

    #region Constructors

    /// <summary>
    /// The constructor for CssCharSetRule
    /// </summary>
    /// <param name="match">The Regex match that found the charset rule</param>
    /// <param name="parent">The parent rule or parent stylesheet</param>
    /// <param name="readOnly">True if this instance is readonly</param>
    /// <param name="replacedStrings">An array of strings that have been replaced in the string used for matching. These needs to be put back use the DereplaceStrings method</param>
    /// <param name="origin">The type of CssStyleSheet</param>
        internal CssCharsetRule(Match match, object parent, bool readOnly, 
            IList<string> replacedStrings, CssStyleSheetType origin)
            : base(parent, readOnly, replacedStrings, origin)
    {
      _Encoding = DeReplaceStrings(match.Groups["charsetencoding"].Value);
    }

    #endregion
    
    #region Implementation of ICssCharsetRule
    private string _Encoding;
    /// <summary>
    /// The encoding information used in this @charset rule
    /// </summary>
    public string Encoding
    {
      get
      {
        return _Encoding;
      }
      set
      {
        /*
         * TODO: SYNTAX_ERR: Raised if the specified encoding value has a syntax error and is unparsable.
         * */

        if (readOnly) 
                    throw new DomException(DomExceptionType.NoModificationAllowedErr);

        _Encoding = value;
      }
    }
    #endregion

    #region Implementation of ICssRule
    /// <summary>
    /// The type of the rule. The expectation is that binding-specific casting methods can be used to cast down from an instance of the CSSRule interface to the specific derived interface implied by the type.
    /// </summary>
    public override CssRuleType Type
    {
      get
      {
        return CssRuleType.CharsetRule;
      }
    }
    #endregion
  }
}