/// <summary>
/// Parses the given template string into a <see cref="TemplateTree"/> using standard technique
/// of preprocessing then lexical analysis followed by a syntactic analysis
/// </summary>
/// <param name="template">The template string to parse</param>
/// <returns>A <see cref="TemplateTree"/> which is the abstract representation of the given string</returns>
public static TemplateTree Parse(string template)
{
string preprocessedTemplate = Preprocess(template);
if (preprocessedTemplate == null)
{
return(null);
}
IEnumerable <string> tokenStream = Tokenize(preprocessedTemplate);
TemplateTree result = ParseTokenStream(tokenStream);
return(result);
}
private static TemplateTree ParseTokenStream(IEnumerable <string> tokenStream)
{
// Structure expressions (like *if and *foreach) cause the state to be pushed in this stack
var stack = new Stack <(StructureBase, TemplateTree)>();
// State
var currentTemplate = new TemplateTree();
var currentStruct = default(StructureBase);
bool insideCurlies = false;
foreach (var token in tokenStream)
{
if (token == "{{")
{
insideCurlies = true;
}
else if (token == "}}")
{
insideCurlies = false;
}
else if (insideCurlies)
{
var tokenTrim = token.Trim();
if (tokenTrim.StartsWith("*")) // Inside the curlies, starts with an asterisk *: Structure component
{
// If it's an *end component, pop the state stack
if (tokenTrim.ToLower() == StructureBase._end || tokenTrim.ToLower().StartsWith(StructureBase._end + " "))
{
if (stack.Count == 0)
{
throw new TemplateException("Unexpected expression {{" + token + "}}");
}
// Pop the previous state
(currentStruct, currentTemplate) = stack.Pop();
}
else // If it's anything other then *end, push the state in the stack
{
// Parse the token and add it to the current template
var templateStructure = StructureBase.Parse(tokenTrim);
currentTemplate.Contents.Add(templateStructure);
// Start of a structural block
// Push the current state into the stack
stack.Push((currentStruct, currentTemplate));
// Start a fresh state
currentStruct = templateStructure;
currentTemplate = new TemplateTree();
currentStruct.Template = currentTemplate;
}
}
else // Inside the curlies, does not start with an asterisk *: An expression
{
currentTemplate.Contents.Add(TemplexBase.Parse(token));
}
}
else // Outside the curlies: Plain markup
{
currentTemplate.Contents.Add(TemplateMarkup.Make(token));
}
}
// All scopes that weren't explicitly closed, do so implicitly at the end of the template
// Keep popping until you're back at the root
while (stack.Count > 0)
{
(_, currentTemplate) = stack.Pop();
}
return(currentTemplate);
}