/// <summary>
/// Constructs a DOM (System.Xml.Linq.XDocument) from HTML markup.
/// </summary>
/// <param name="htmlContent">HTML markup from which the DOM is to be constructed.</param>
/// <returns>System.Linq.Xml.XDocument instance which is a DOM of the provided HTML markup.</returns>
public XDocument BuildDocument(string htmlContent)
{
if (htmlContent == null)
{
throw new ArgumentNullException("htmlContent");
}
if (htmlContent.Trim().Length == 0)
{
return(new XDocument());
}
// Remove all conditional comments (SgmlDomBuilder doesn't understand them correctly)
htmlContent = Regex.Replace(htmlContent, @"<!--\s*\[if .*?\]\s*>.*?<!\s*\[endif\]\s*-->", string.Empty, RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Compiled);
htmlContent = Regex.Replace(htmlContent, @"<!--\s*\[if .*?\]\s*>\s*(-->)?", string.Empty, RegexOptions.IgnoreCase | RegexOptions.Compiled);
htmlContent = Regex.Replace(htmlContent, @"(<!--\s*)?<!\s*\[endif\]\s*-->", string.Empty, RegexOptions.IgnoreCase | RegexOptions.Compiled);
// remove malformed conditionals
htmlContent = Regex.Replace(htmlContent, @"<!--\s*\[if .*?>\s*-->", string.Empty, RegexOptions.IgnoreCase | RegexOptions.Compiled);
// "trim end" htmlContent to ...</html>$ (codinghorror.com puts some scripts after the </html> - sic!)
const string htmlEnd = "</html";
int indexOfHtmlEnd = htmlContent.LastIndexOf(htmlEnd);
if (indexOfHtmlEnd != -1)
{
int indexOfHtmlEndBracket = htmlContent.IndexOf('>', indexOfHtmlEnd);
if (indexOfHtmlEndBracket != -1)
{
htmlContent = htmlContent.Substring(0, indexOfHtmlEndBracket + 1);
}
}
// "trim start" htmlContent to ...^<html (some sites put scripts before the <html>..)
const string htmlStart = "<html";
int indexOfHtmlStart = htmlContent.IndexOf(htmlStart);
if (indexOfHtmlStart != -1)
{
htmlContent = htmlContent.Substring(indexOfHtmlStart);
}
XDocument document;
try
{
document = LoadDocument(htmlContent);
}
catch (InvalidOperationException exc)
{
// sometimes SgmlReader doesn't handle <script> tags well and XDocument.Load() throws,
// so we can retry with the html content with <script> tags stripped off
if (!exc.Message.Contains("EndOfFile"))
{
throw;
}
htmlContent = HtmlUtils.RemoveScriptTags(htmlContent);
try
{
document = LoadDocument(htmlContent);
}
catch (InvalidOperationException exc2)
{
// if removing the script tags wasn't enough, we can retry with the
// <style> tags also stripped off
if (!exc2.Message.Contains("EndOfFile"))
{
throw;
}
htmlContent = HtmlUtils.RemoveStyleTags(htmlContent);
document = LoadDocument(htmlContent);
}
}
// remove any *extra* <body> or <html> tags
Action <XDocument, string> fnRemoveExtra = (doc, tagName) =>
{
var bodyElements = doc.GetElementsByTagName(tagName);
if (bodyElements != null && bodyElements.Count() > 1)
{
// Skip the first (top-most) match, then reverse the list so they're processed bottom-up
foreach (var bodyElem in bodyElements.Skip(1).Reverse())
{
// Push any child nodes up a level, then delete the body element
var children = bodyElem.Descendants();
bodyElem.AddAfterSelf(children.ToArray());
bodyElem.Remove();
}
}
};
fnRemoveExtra(document, "html");
fnRemoveExtra(document, "body");
return(document);
}
