// ---------------------------------------------------------------------
//
// Private methods
//
// ---------------------------------------------------------------------
#region Private Methods
/// <summary>
/// Advances a reading position by one character code
/// and reads the next availbale character from a stream.
/// This character becomes available as NextCharacter property.
/// </summary>
/// <remarks>
/// Throws InvalidOperationException if attempted to be called on EndOfStream
/// condition.
/// </remarks>
private void GetNextCharacter()
{
if (_nextCharacterCode == -1)
{
throw new InvalidOperationException("GetNextCharacter method called at the end of a stream");
}
_previousCharacter = _nextCharacter;
_nextCharacter = _lookAheadCharacter;
_nextCharacterCode = _lookAheadCharacterCode;
// next character not an entity as of now
_isNextCharacterEntity = false;
this.ReadLookAheadCharacter();
if (_nextCharacter == '&')
{
if (_lookAheadCharacter == '#')
{
// numeric entity - parse digits - &#DDDDD;
int entityCode;
entityCode = 0;
this.ReadLookAheadCharacter();
// largest numeric entity is 7 characters
for (int i = 0; i < 7 && Char.IsDigit(_lookAheadCharacter); i++)
{
entityCode = 10 * entityCode + (_lookAheadCharacterCode - (int)'0');
this.ReadLookAheadCharacter();
}
if (_lookAheadCharacter == ';')
{
// correct format - advance
this.ReadLookAheadCharacter();
_nextCharacterCode = entityCode;
// if this is out of range it will set the character to '?'
_nextCharacter = (char)_nextCharacterCode;
// as far as we are concerned, this is an entity
_isNextCharacterEntity = true;
}
else
{
// not an entity, set next character to the current lookahread character
// we would have eaten up some digits
_nextCharacter = _lookAheadCharacter;
_nextCharacterCode = _lookAheadCharacterCode;
this.ReadLookAheadCharacter();
_isNextCharacterEntity = false;
}
}
else if (Char.IsLetter(_lookAheadCharacter))
{
// entity is written as a string
string entity = "";
// maximum length of string entities is 10 characters
for (int i = 0; i < 10 && (Char.IsLetter(_lookAheadCharacter) || Char.IsDigit(_lookAheadCharacter)); i++)
{
entity += _lookAheadCharacter;
this.ReadLookAheadCharacter();
}
if (_lookAheadCharacter == ';')
{
// advance
this.ReadLookAheadCharacter();
if (HtmlSchema.IsEntity(entity))
{
_nextCharacter = HtmlSchema.EntityCharacterValue(entity);
_nextCharacterCode = (int)_nextCharacter;
_isNextCharacterEntity = true;
}
else
{
// just skip the whole thing - invalid entity
// move on to the next character
_nextCharacter = _lookAheadCharacter;
_nextCharacterCode = _lookAheadCharacterCode;
this.ReadLookAheadCharacter();
// not an entity
_isNextCharacterEntity = false;
}
}
else
{
// skip whatever we read after the ampersand
// set next character and move on
_nextCharacter = _lookAheadCharacter;
this.ReadLookAheadCharacter();
_isNextCharacterEntity = false;
}
}
}
}
/// <summary>
/// Parses the stream of html tokens starting
/// from the name of top-level element.
/// Returns XmlElement representing the top-level
/// html element
/// </summary>
private XmlElement ParseHtmlContent()
{
// Create artificial root elelemt to be able to group multiple
// top-level elements. We create "html" element which may be a
// duplicate of the real HTML element (a duplicate HTML element
// is ok since HtmlConverter will process it without a problem).
XmlElement htmlRootElement = _document.CreateElement("html", XhtmlNamespace);
OpenStructuringElement(htmlRootElement);
while (_htmlLexicalAnalyzer.NextTokenType != HtmlTokenType.EOF)
{
if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.OpeningTagStart)
{
_htmlLexicalAnalyzer.GetNextTagToken();
if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.Name)
{
string htmlElementName = _htmlLexicalAnalyzer.NextToken.ToLower();
_htmlLexicalAnalyzer.GetNextTagToken();
// Create an element
XmlElement htmlElement = _document.CreateElement(htmlElementName, XhtmlNamespace);
// Parse element attributes
ParseAttributes(htmlElement);
if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.EmptyTagEnd || HtmlSchema.IsEmptyElement(htmlElementName))
{
// It is an element without content (because of explicit slash or based on implicit knowledge aboout html)
AddEmptyElement(htmlElement);
}
else if (HtmlSchema.IsInlineElement(htmlElementName))
{
// Elements known as formatting are pushed to some special
// pending stack, which allows them to be transferred
// over block tags - by doing this we convert
// overlapping tags into normal heirarchical element structure.
OpenInlineElement(htmlElement);
}
else if (HtmlSchema.IsBlockElement(htmlElementName) || HtmlSchema.IsKnownOpenableElement(htmlElementName))
{
// This includes no-scope elements
OpenStructuringElement(htmlElement);
}
else
{
// Do nothing. Skip the whole opening tag.
// Ignoring all unknown elements on their start tags.
// Thus we will ignore them on closinng tag as well.
// Anyway we don't know what to do withthem on conversion to Xaml.
}
}
else
{
// Note that the token following opening angle bracket must be a name - lexical analyzer must guarantee that.
// Otherwise - we skip the angle bracket and continue parsing the content as if it is just text.
// TODO: Add the following asserion here, right? or output "<" as a text run instead?:
// InvariantAssert(false, "Angle bracket without a following name is not expected");
}
}
else if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.ClosingTagStart)
{
_htmlLexicalAnalyzer.GetNextTagToken();
if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.Name)
{
string htmlElementName = _htmlLexicalAnalyzer.NextToken.ToLower();
// Skip the name token. Assume that the following token is end of tag,
// but do not check this. If it is not true, we simply ignore one token
// - this is our recovery from bad xml in this case.
_htmlLexicalAnalyzer.GetNextTagToken();
CloseElement(htmlElementName);
}
}
else if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.Text)
{
AddTextContent(_htmlLexicalAnalyzer.NextToken);
}
else if (_htmlLexicalAnalyzer.NextTokenType == HtmlTokenType.Comment)
{
AddComment(_htmlLexicalAnalyzer.NextToken);
}
_htmlLexicalAnalyzer.GetNextContentToken();
}
// Get rid of the artificial root element
if (htmlRootElement.FirstChild is XmlElement &&
htmlRootElement.FirstChild == htmlRootElement.LastChild &&
htmlRootElement.FirstChild.LocalName.ToLower() == "html")
{
htmlRootElement = (XmlElement)htmlRootElement.FirstChild;
}
return(htmlRootElement);
}