internal static void NotNullExpression(ISelectorAttribute selector)
{
if (string.IsNullOrWhiteSpace(selector.Expression))
{
throw new ArgumentException($"Expression of {selector} should not be null/empty.");
}
}
public static void NotNullExpression(ISelectorAttribute selector)
{
if (string.IsNullOrEmpty(selector.Expression))
{
throw new SpiderException($"Expression of {selector} should not be null/empty.");
}
}
/// <summary>
/// 把BaseSelector转换成真正的查询器
/// </summary>
/// <param name="selector">BaseSelector</param>
/// <returns>查询器</returns>
public static ISelector ToSelector(this ISelectorAttribute selector)
{
if (selector != null)
{
string expression = selector.Expression;
switch (selector.Type)
{
case SelectorType.Css:
{
NotNullExpression(selector);
return(Selectors.Css(expression));
}
case SelectorType.Enviroment:
{
return(Selectors.Enviroment(expression));
}
case SelectorType.JsonPath:
{
NotNullExpression(selector);
return(Selectors.JsonPath(expression));
}
case SelectorType.Regex:
{
NotNullExpression(selector);
if (string.IsNullOrEmpty(selector.Arguments))
{
return(Selectors.Regex(expression));
}
else
{
if (int.TryParse(selector.Arguments, out var group))
{
return(Selectors.Regex(expression, group));
}
throw new SpiderException("Regex argument should be a number set to group: " + selector);
}
}
case SelectorType.XPath:
{
NotNullExpression(selector);
return(Selectors.XPath(expression));
}
default:
{
throw new SpiderException($"Selector {selector} unsupoort");
}
}
}
else
{
return(null);
}
}
