private int Shift(int position, Stack stack, Terminal textPosition, ParserAction parserAction,
ParseReportModel parseReport)
{
position++;
stack.Push(textPosition);
stack.Push(parserAction.ShiftState);
parseReport.Output = "Shift to state " + parserAction.ShiftState;
Nodes.Push(new TreeNode(textPosition, OrderId++));
return(position);
}
public bool Parse(List <Terminal> terminals, IProgress <ParseReportModel> report)
{
Terminal[] text = terminals.ToArray();
Stack stack = new Stack();
stack.Push(0);
ParseReportModel firstReport = new ParseReportModel();
firstReport.InputString = string.Join <Terminal>("", text);
firstReport.Output = "Pushing 0 to the stack";
firstReport.Stack = string.Join("", stack.ToArray());
report.Report(firstReport);
int position = 0;
while (stack.Count > 0)
{
ParseReportModel parseReport = new ParseReportModel();
parseReport.Stack = string.Join("", stack.ToArray().Reverse());
parseReport.InputString = string.Join("", terminals.Skip(position));
int peek = (int)stack.Peek();
var textPosition = text[position];
var parserAction = _grammarTable.GetParserAction(peek, textPosition);
if (parserAction == null)
{
parseReport.Output = "No Parser Action is found";
report.Report(parseReport);
return(false);
}
if (parserAction.Action == Action.Accept)
{
parseReport.Output = "Success";
report.Report(parseReport);
return(true);
}
if (parserAction.Action == Action.Reduce)
{
if (!Reduce(terminals, report, parserAction, stack, parseReport, position))
{
return(false);
}
}
else if (parserAction.Action == Action.Shift)
{
position = Shift(position, stack, textPosition, parserAction, parseReport);
}
parseReport.InputString = string.Join("", terminals.Skip(position));
parseReport.Stack = string.Join("", stack.ToArray().Reverse());
report.Report(parseReport);
}
return(false);
}
private bool Reduce(List <Terminal> terminals, IProgress <ParseReportModel> report, ParserAction parserAction, Stack stack,
ParseReportModel parseReport, int position)
{
int peek;
int countpop = parserAction.Handle.Count();
ISymbol[] symbols = parserAction.Handle.Reverse().ToArray();
if (!parserAction.Handle.Contains(Terminal.Epsilon))
{
TreeNode node = new TreeNode(parserAction.Variable, OrderId++);
for (int i = 0; i < countpop; i++)
{
stack.Pop(); //pop the number
ISymbol pop = (ISymbol)stack.Pop();
node.Nodes.Add(Nodes.Pop());
if (!symbols[i].Equals(pop))
{
parseReport.Stack = string.Join("", stack.ToArray().Reverse());
parseReport.InputString = string.Join("", terminals.Skip(position));
parseReport.Output = "symbol is not equal to the top of stack";
report.Report(parseReport);
return(false);
}
}
Nodes.Push(node);
}
else
{
var item = new TreeNode(Terminal.Epsilon, OrderId++);
var treeNode = new TreeNode(parserAction.Variable, OrderId++);
treeNode.Nodes.Add(item);
Nodes.Push(treeNode);
}
peek = (int)stack.Peek();
stack.Push(parserAction.Variable);
var goTo = _grammarTable.GetGoTo(peek, parserAction.Variable);
if (goTo == null)
{
parseReport.Stack = string.Join("", stack.ToArray().Reverse());
parseReport.Output = "GoTo table is null";
report.Report(parseReport);
return(false);
}
stack.Push(goTo.StateId);
parseReport.Output =
$"Reduce {countpop}.Push {parserAction.Variable}::={string.Join("", parserAction.Handle)} .GoTo {goTo.StateId}";
return(true);
}
private void Progress_ProgressChanged(object sender, ParseReportModel e)
{
dataGridViewReport.Rows.Add(e.Stack, e.InputString, e.Output);
}