/// <summary>
/// Finds the sub snippet with the given tagname in the parenting tag node.
/// </summary>
/// <param name="tagNode">The parenting tag node</param>
/// <param name="snippetName">The subtag to search</param>
/// <returns>The sub snippet if it is found or <c>null</c> otherwise</returns>
/// <exception cref="FormatException">Thrown if the subtag has more than just a single <see cref="TMLTerminalNode"/>.</exception>
private SubSnippet FindSubSnippet(TMLTagNode tagNode, string snippetName)
{
var subnode = tagNode.InnerNodes.Where(n => n is TMLTagNode).Select(n => (TMLTagNode)n).Where(n => n.TagName == snippetName).FirstOrDefault();
if (subnode != null && subnode.InnerNodes.Count > 0)
{
//only single inner node allowed
if (subnode.InnerNodes.Count > 1 || !(subnode.InnerNodes.First() is TMLTerminalNode))
{
throw new FormatException("The solution tag may not have nested tags.");
}
return(ParseTrimmedContent((TMLTerminalNode)subnode.InnerNodes.First()));
}
return(null);
}
/// <summary>
/// Constructs the abstract syntax tree from a given text.
/// </summary>
/// <param name="text">The original text to analyze</param>
/// <exception cref="FormatException">Thrown if the number of opening and closing tags to not match or if an unexpected closing tag is encountered.</exception>
public TMLSyntaxTree(string text)
{
//Setup the regex patterns to match opening and closing tags
var tagStartRegex = new Regex(@"//<(?<tag>\w+)(?<attributes>[^>]*?)(?<!/)>");
var tagEndRegex = new Regex(@"//</(?<tag>\w+)>");
var attributesRegex = new Regex("\\b(?<key>\\w+)\\b=\"(?<value>.*?)\"");
//Find the opening and closing tags
var tagStartMatches = tagStartRegex.Matches(text);
var tagEndMatches = tagEndRegex.Matches(text);
if (tagStartMatches.Count != tagEndMatches.Count)
{
throw new FormatException($"There are {tagStartMatches.Count} opening tags but {tagEndMatches.Count} closing tags.");
}
//the character index where the last text portion (i.e. non-tag text) started
var lastTextPosition = 0;
//the index of the next tag start within tagStartMatches
int nextTagStart = 0;
//the index of the next tag end within tagEndMatches
int nextTagEnd = 0;
//stack of currently open tags
var tagStack = new Stack <TMLTagNode>();
//go through the matched opening and closing tags in order
while (nextTagStart < tagStartMatches.Count || nextTagEnd < tagEndMatches.Count)
{
//character index of the next opening tag or text.Length if there are no more opening tags
int nextStartPosition = (nextTagStart < tagStartMatches.Count ? tagStartMatches[nextTagStart].Index : text.Length);
//character index of the next closing tag or text.length if there are no more closing tags
int nextEndPosition = (nextTagEnd < tagEndMatches.Count ? tagEndMatches[nextTagEnd].Index : text.Length);
//character index of the next opening or closing tag
int nextPosition = Math.Min(nextStartPosition, nextEndPosition);
//list of children of the tag we are currently in (either the global list or the child list of a node)
var childrenOfParentNode = (tagStack.Count == 0 ? Nodes : tagStack.Peek().InnerNodes);
//Add text nodes if the next tag is not at the current position
if (nextPosition > lastTextPosition)
{
childrenOfParentNode.Add(new TMLTerminalNode()
{
BeginIndex = lastTextPosition, Length = nextPosition - lastTextPosition
});
}
if (nextStartPosition < nextEndPosition)
{
//The next tag is an opening one
var match = tagStartMatches[nextTagStart++];
var tag = new TMLTagNode()
{
TagName = match.Groups["tag"].Value, OpeningTagBeginIndex = match.Index, OpeningTagLength = match.Length
};
//Gather the attributes
var attributesString = match.Groups["attributes"].Value;
var attributeMatches = attributesRegex.Matches(attributesString);
foreach (Match a in attributeMatches)
{
tag.Attributes[a.Groups["key"].Value] = a.Groups["value"].Value;
}
//Add the new tag to the parent
childrenOfParentNode.Add(tag);
//move into this tag
tagStack.Push(tag);
lastTextPosition = match.Index + match.Length;
}
else
{
//The next tag is a closing one
var match = tagEndMatches[nextTagEnd++];
var tagname = match.Groups["tag"].Value;
if (tagStack.Count == 0)
{
throw new FormatException($"Encountered a closing tag of {tagname} but expected no closing tag.");
}
if (tagStack.Peek().TagName != tagname)
{
throw new FormatException($"Encountered a closing tag of {tagname} but expected a closing tag of {tagStack.Peek().TagName}.");
}
//leave the tag
var tag = tagStack.Pop();
tag.ClosingTagBeginIndex = match.Index;
tag.ClosingTagLength = match.Length;
lastTextPosition = match.Index + match.Length;
}
}
//Add a text node for everything after the last tag
if (text.Length > lastTextPosition)
{
Nodes.Add(new TMLTerminalNode()
{
BeginIndex = lastTextPosition, Length = text.Length - lastTextPosition
});
}
}
