/// <summary>
/// 使用选择器从元素集中筛选出符合选择器要求的元素
/// </summary>
/// <param name="source">源元素集</param>
/// <param name="selector">选择器</param>
/// <returns>筛选结果</returns>
public static IEnumerable <IHtmlElement> FilterBy(this IEnumerable <IHtmlElement> source, string selector)
{
if (source == null)
{
return(null);
}
if (string.IsNullOrEmpty(selector))
{
return(source);
}
return(FilterBy(source, CssParser.ParseSelector(selector)));
}
/// <summary>
/// 派生类重写此方法确定指定元素是否需要重写渲染规则
/// </summary>
/// <param name="element">要检测的元素</param>
/// <returns>是否需要使用自定义渲染规则</returns>
protected virtual bool IsEligible(IHtmlElement element)
{
if (CssSelector == null)
{
return(false);
}
if (_selectorExpression == CssSelector)
{
return(_selectorCache.IsEligible(element));
}
_selectorExpression = CssSelector;
_selectorCache = CssParser.ParseSelector(CssSelector);
return(_selectorCache.IsEligible(element));
}
/// <summary>
/// 创建层叠选择器
/// </summary>
/// <param name="elements">作为范畴限定的元素集</param>
/// <param name="expression">选择器表达式</param>
/// <returns>层叠选择器</returns>
public static ISelector Create(IEnumerable <IHtmlElement> elements, string expression)
{
if (elements == null)
{
throw new ArgumentNullException("elements");
}
if (expression == null)
{
throw new ArgumentNullException("expression");
}
var selector = CssParser.ParseSelector(expression);
if (elements.IsNullOrEmpty())
{
return(selector);
}
var relativeSelector = new CssAncetorRelativeSelector(new CssElementsRestrictionSelector(elements));
return(Create(relativeSelector, selector));
}
/// <summary>
/// 创建带范畴限定的选择器
/// </summary>
/// <param name="expression">选择器表达式</param>
/// <param name="scope">范畴限定，上溯时不超出此范畴</param>
/// <returns>带范畴限定的层叠选择器</returns>
public static ISelector Create(IHtmlContainer scope, string expression)
{
if (scope == null)
{
throw new ArgumentNullException("scope");
}
if (expression == null)
{
throw new ArgumentNullException("expression");
}
return(CssCasecadingSelector.Create(new CssAncetorRelativeSelector(new ContainerRestrict(scope)), CssParser.ParseSelector(expression)));
}
/// <summary>
/// 获取符合条件的子代元素
/// </summary>
/// <param name="container">要获取子代元素的容器对象</param>
/// <param name="selector">用于筛选子代元素的选择器</param>
/// <returns>符合选择器的容器的所有子代元素</returns>
/// <remarks>与Find方法不同的是，Descendants方法的选择器会无限上溯，即当判断父代约束时，会无限上溯到文档根。而Find方法只会上溯到自身的子节点</remarks>
public static IEnumerable <IHtmlElement> Descendants(this IHtmlContainer container, string selector)
{
return(CssParser.ParseSelector(selector).Filter(Descendants(container)));
}
