/// <summary>
/// Invoked when a block is entered to create a new statements context
/// which will received all subsequent statements.
/// </summary>
public void EnterBlock(ParseTreeNode tag)
{
_blocks.Push(CurrentBlock);
CurrentBlock = new BlockContext(tag);
}
/// <summary>
/// Invoked when the end of a block has been reached.
/// It resets the current statements context to the outer block.
/// </summary>
public void ExitBlock()
{
CurrentBlock = _blocks.Pop();
}
protected bool _isRaw; // true when the current block is raw
public bool TryParse(StringSegment template, out IList <Statement> result, out IEnumerable <string> errors)
{
errors = Array.Empty <string>();
Parser parser = null;
_currentContext = new BlockContext(null);
_contexts = new Stack <BlockContext>();
result = _currentContext.Statements;
try
{
int previous = 0, index = 0;
Statement s;
while (true)
{
previous = index;
if (!MatchTag(template, index, out var start, out var end))
{
index = template.Length;
if (index != previous)
{
// Consume last Text statement
ConsumeTextStatement(template, previous, index);
}
break;
}
else
{
if (parser == null)
{
parser = new Parser(_language);
}
if (start != previous)
{
// Consume current Text statement
ConsumeTextStatement(template, previous, start);
}
var tag = template.Substring(start, end - start + 1);
var tree = parser.Parse(tag);
if (tree.HasErrors())
{
errors = tree
.ParserMessages
.Select(x => $"{x.Message} at line:{x.Location.Line}, col:{x.Location.Column}")
.ToArray();
return(false);
}
switch (tree.Root.Term.Name)
{
case "output":
s = BuildOutputStatement(tree.Root);
break;
case "tag":
s = BuildTagStatement(tree.Root);
break;
default:
s = null;
break;
}
if (s != null)
{
_currentContext.Statements.Add(s);
}
index = end + 1;
}
}