/// <summary>
/// 合并两个关系选择器
/// </summary>
/// <param name="left">左关系选择器</param>
/// <param name="right">右关系选择器</param>
/// <returns>合并后的关系选择器</returns>
public static CssRelativeSelector Combine( CssRelativeSelector left, CssRelativeSelector right )
{
if ( left == null )
throw new ArgumentNullException( "left" );
if ( right == null )
throw new ArgumentNullException( "right" );
var selector = right.LeftSelector;
var combinator = right.Combinator;
var casecadingSelector = selector as CssCasecadingSelector;
if ( casecadingSelector != null ) //如果右边关系选择器的左选择器是一个层叠选择器
return CreateRelativeSelector( CssCasecadingSelector.Combine( left, casecadingSelector ), combinator );//将层叠选择器与左边的关系选择器合并，得到一个新的层叠选择器，再根据结合符创建新的关系选择器。
/*
* 举例说明如下：
* 假设左关系选择器是 p>，右关系选择器是 div>ul>li+
* 则右关系选择器的左选择器(selector)是div>ul>li，结合符(combinator)是+。
* 将selector与左边的关系选择器合并，得到：p>div>ul>li，再与结合符结合得到新的关系选择器：p>div>ul>li+
*/
var elementSelector = selector as CssElementSelector;
if ( elementSelector != null )
return CreateRelativeSelector( new CssCasecadingSelector( left, elementSelector ), combinator );
throw new NotSupportedException();
}
/// <summary>
/// 创建 CSS 层叠选择器对象
/// </summary>
/// <param name="relativeSelector">关系选择器</param>
/// <param name="lastSelector">附加的最后一个选择器</param>
public CssCasecadingSelector( CssRelativeSelector relativeSelector, ISelector lastSelector )
{
if ( relativeSelector == null )
throw new ArgumentNullException( "relativeSelector" );
if ( lastSelector == null )
throw new ArgumentNullException( "lastSelector" );
RelativeSelector = relativeSelector;
LastSelector = lastSelector;
}
/// <summary>
/// 创建 CSS 层叠选择器对象
/// </summary>
/// <param name="relativeSelector">关系选择器</param>
/// <param name="lastSelector">附加的最后一个选择器</param>
public CssCasecadingSelector(CssRelativeSelector relativeSelector, ISelector lastSelector)
{
if (relativeSelector == null)
{
throw new ArgumentNullException("relativeSelector");
}
if (lastSelector == null)
{
throw new ArgumentNullException("lastSelector");
}
RelativeSelector = relativeSelector;
LastSelector = lastSelector;
}
/// <summary>
/// 合并两个关系选择器
/// </summary>
/// <param name="left">左关系选择器</param>
/// <param name="right">右关系选择器</param>
/// <returns>合并后的关系选择器</returns>
public static CssRelativeSelector Combine(CssRelativeSelector left, CssRelativeSelector right)
{
if (left == null)
{
throw new ArgumentNullException("left");
}
if (right == null)
{
throw new ArgumentNullException("right");
}
var selector = right.LeftSelector;
var combinator = right.Combinator;
var casecadingSelector = selector as CssCasecadingSelector;
if (casecadingSelector != null) //如果右边关系选择器的左选择器是一个层叠选择器
{
return(CreateRelativeSelector(CssCasecadingSelector.Combine(left, casecadingSelector), combinator)); //将层叠选择器与左边的关系选择器合并，得到一个新的层叠选择器，再根据结合符创建新的关系选择器。
}
/*
* 举例说明如下：
* 假设左关系选择器是 p>，右关系选择器是 div>ul>li+
* 则右关系选择器的左选择器(selector)是div>ul>li，结合符(combinator)是+。
* 将selector与左边的关系选择器合并，得到：p>div>ul>li，再与结合符结合得到新的关系选择器：p>div>ul>li+
*/
var elementSelector = selector as CssElementSelector;
if (elementSelector != null)
{
return(CreateRelativeSelector(new CssCasecadingSelector(left, elementSelector), combinator));
}
throw new NotSupportedException();
}
/// <summary>
/// 创建层叠选择器
/// </summary>
/// <param name="relativeSelector">前置关系选择器</param>
/// <param name="selector">右选择器</param>
/// <returns></returns>
public static ISelector Create(CssRelativeSelector relativeSelector, ISelector selector)
{
if (relativeSelector == null)
{
throw new ArgumentNullException("relativeSelector");
}
if (selector == null)
{
throw new ArgumentNullException("selector");
}
var elementSelector = selector as CssElementSelector;
if (elementSelector != null)
{
return(new CssCasecadingSelector(relativeSelector, elementSelector));
}
var casecadingSelector = selector as CssCasecadingSelector;
if (casecadingSelector != null)
{
return(Combine(relativeSelector, casecadingSelector));
}
var multipleSelector = selector as CssMultipleSelector;
if (multipleSelector != null)
{
return(CssMultipleSelector.Combine(relativeSelector, multipleSelector));
}
throw new NotSupportedException();
}
/// <summary>
/// 合并关系选择器和层叠选择器
/// </summary>
/// <param name="relativeSelector">关系选择器</param>
/// <param name="selector">层叠选择器</param>
/// <returns></returns>
internal static CssCasecadingSelector Combine(CssRelativeSelector relativeSelector, CssCasecadingSelector selector)
{
relativeSelector = Combine(relativeSelector, selector.RelativeSelector);
return(new CssCasecadingSelector(relativeSelector, selector.LastSelector));
}
public static ISelector Combine( CssRelativeSelector relativeSelector, CssMultipleSelector multipleSelector )
{
return new CssMultipleSelector( multipleSelector._selectors.Select( selector => CssCasecadingSelector.Create( relativeSelector, selector ) ).ToArray() );
}
public static ISelector Combine(CssRelativeSelector relativeSelector, CssMultipleSelector multipleSelector)
{
return(new CssMultipleSelector(multipleSelector._selectors.Select(selector => CssCasecadingSelector.Create(relativeSelector, selector)).ToArray()));
}
/// <summary>
/// 合并关系选择器和层叠选择器
/// </summary>
/// <param name="relativeSelector">关系选择器</param>
/// <param name="selector">层叠选择器</param>
/// <returns></returns>
internal static CssCasecadingSelector Combine( CssRelativeSelector relativeSelector, CssCasecadingSelector selector )
{
relativeSelector = Combine( relativeSelector, selector.RelativeSelector );
return new CssCasecadingSelector( relativeSelector, selector.LastSelector );
}
/// <summary>
/// 创建层叠选择器
/// </summary>
/// <param name="relativeSelector">前置关系选择器</param>
/// <param name="selector">右选择器</param>
/// <returns></returns>
public static ISelector Create( CssRelativeSelector relativeSelector, ISelector selector )
{
if ( relativeSelector == null )
throw new ArgumentNullException( "relativeSelector" );
if ( selector == null )
throw new ArgumentNullException( "selector" );
var elementSelector = selector as CssElementSelector;
if ( elementSelector != null )
return new CssCasecadingSelector( relativeSelector, elementSelector );
var casecadingSelector = selector as CssCasecadingSelector;
if ( casecadingSelector != null )
return Combine( relativeSelector, casecadingSelector );
var multipleSelector = selector as CssMultipleSelector;
if ( multipleSelector != null )
return CssMultipleSelector.Combine( relativeSelector, multipleSelector );
throw new NotSupportedException();
}