/// <summary>
/// Given an expression, it will parse it and return the result as a nullable ushort
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public ExpressionResult ParseExpression(string value)
{
ExpressionResult expressionResult = new ExpressionResult();
expressionResult.Successful = true;
expressionResult.References = new List <string>();
value = value.Trim();
if (HandleExpression != null)
{
HandleExpressionEventArgs heea = new HandleExpressionEventArgs(value);
HandleExpression(this, heea);
value = heea.Expression;
}
if (value.SafeContains('('))
{
// Check for advanced expression handlers
foreach (var item in ExpressionExtensions)
{
if (value.StartsWith(item.Key.ToLower() + "("))
{
string expr = value.Substring(value.SafeIndexOf('(') + 1);
expr = expr.Remove(expr.Length - 1);
expressionResult.Value = item.Value(expr);
return(expressionResult);
}
}
return(EvaluateParenthesis(value));
}
if (value.StartsWith("~"))
{
expressionResult = ParseExpression(value.Substring(1));
if (expressionResult.Successful)
{
expressionResult.Value = (ushort)~expressionResult.Value;
}
return(expressionResult);
}
if (!HasOperators(value))
{
// Parse value
ushort result;
EvaluateValueEventArgs args = new EvaluateValueEventArgs(value);
if (EvaluateExpressionValue != null)
{
EvaluateExpressionValue(this, args);
}
if (args.Handled)
{
expressionResult.Value = args.Result;
return(expressionResult);
}
else if (value.StartsWith("0d"))
{
value = value.Substring(2);
}
if (value.StartsWith("'")) // Character
{
if (value.Length < 3)
{
expressionResult.Successful = false;
return(expressionResult);
}
value = value.Substring(1, value.Length - 2).Unescape();
if (value == null)
{
expressionResult.Successful = false;
return(expressionResult);
}
if (value.Length != 1)
{
expressionResult.Successful = false;
return(expressionResult);
}
expressionResult.Value = (ushort)Encoding.ASCII.GetBytes(value)[0];
return(expressionResult);
}
else if (value.StartsWith("{") && value.EndsWith("}")) // instruction literal
{
string instruction = value.Substring(1, value.Length - 2);
Assembler subAssembler = new Assembler();
List <ListEntry> assembly = subAssembler.Assemble(instruction);
if (assembly.Count == 0)
{
expressionResult.Successful = false;
return(expressionResult);
}
if (assembly[0].Output == null)
{
expressionResult.Successful = false;
return(expressionResult);
}
if (assembly[0].Output.Length == 0)
{
expressionResult.Successful = false;
return(expressionResult);
}
expressionResult.Value = assembly[0].Output[0];
return(expressionResult);
}
else if (value.StartsWith("0x")) // Hex
{
value = value.Substring(2);
if (!ushort.TryParse(value.Replace("_", ""), NumberStyles.HexNumber, null, out result))
{
expressionResult.Successful = false;
return(expressionResult);
}
else
{
expressionResult.Value = result;
return(expressionResult);
}
}
else if (value.StartsWith("0b")) // Binary
{
value = value.Substring(2);
ushort?binResult = ParseBinary(value.Replace("_", ""));
if (binResult == null)
{
expressionResult.Successful = false;
}
else
{
expressionResult.Value = binResult.Value;
}
return(expressionResult);
}
else if (value.StartsWith("0o"))
{
value = value.Substring(2);
try
{
expressionResult.Value = Convert.ToUInt16(value.Replace("_", ""), 8);
return(expressionResult);
}
catch
{
expressionResult.Successful = false;
return(expressionResult);
}
}
else if (ushort.TryParse(value.Replace("_", ""), out result)) // Decimal
{
expressionResult.Value = result;
return(expressionResult);
}
else if (value == "$")
{
if (LineNumbers.Count == 0)
{
expressionResult.Successful = false;
return(expressionResult);
}
expressionResult.Value = currentAddress;
return(expressionResult);
}
else if (value.StartsWith("$")) // Relative label
{
if (LineNumbers.Count == 0)
{
expressionResult.Successful = false;
return(expressionResult);
}
value = value.Substring(1);
int nextLabelIndex = -1;
// Find the next relative label after the current line
for (int i = 0; i < RelativeLabels.Count; i++)
{
if (RelativeLabels.ElementAt(i).Key > LineNumbers.Peek())
{
nextLabelIndex = i;
break;
}
}
if (nextLabelIndex == -1)
{
nextLabelIndex = RelativeLabels.Count - 1; // If no such label is found, use the last one
}
bool initialPlus = true;
// For each plus, increment that label index, and each minus decrements it
foreach (char c in value)
{
if (c == '+') // The intial plus symbol is ignored
{
if (initialPlus)
{
nextLabelIndex++;
}
initialPlus = false;
}
else if (c == '-')
{
nextLabelIndex--;
}
}
if (nextLabelIndex < 0)
{
expressionResult.Successful = false;
return(expressionResult);
}
if (nextLabelIndex > RelativeLabels.Count - 1)
{
expressionResult.Successful = false;
return(expressionResult);
}
expressionResult.Value = RelativeLabels.ElementAt(nextLabelIndex).Value;
return(expressionResult);
}
else if (value.ToLower() == "true")
{
expressionResult.Value = 1;
return(expressionResult);
}
else if (value.ToLower() == "false")
{
expressionResult.Value = 0;
return(expressionResult);
}
else // Defined value or error
{
if (value.StartsWith("."))
{
value = PriorGlobalLabel + "_" + value.Substring(1);
}
if (Values.ContainsKey(value))
{
expressionResult.Value = Values[value];
}
else if (LabelValues.ContainsKey(value))
{
expressionResult.Relocate = true;
expressionResult.Value = LabelValues.GetValue(value);
}
else
{
expressionResult.Successful = false;
}
expressionResult.References.Add(value);
if (!ReferencedValues.Contains(value))
{
ReferencedValues.Add(value);
}
return(expressionResult);
}
}
// Parse expression
string[] operands = GetOperands(value);
if (operands == null)
{
expressionResult.Successful = false;
return(expressionResult);
}
if (string.IsNullOrEmpty(operands[0]) && operands[1] == "-")
{
expressionResult = ParseExpression(operands[2]);
expressionResult.Value = (ushort)-expressionResult.Value;
return(expressionResult);
}
if (operands == null)
{
expressionResult.Successful = false;
return(expressionResult);
}
ExpressionResult left = ParseExpression(operands[0]);
ExpressionResult right = ParseExpression(operands[2]);
expressionResult.References.AddRange(left.References.Concat(right.References));
if ((!left.Successful || !right.Successful) && operands[1] != "===" && operands[1] != "!==")
{
expressionResult.Successful = false;
return(expressionResult);
}
switch (operands[1])
{
case "*":
expressionResult.Value = (ushort)(left.Value * right.Value);
break;
case "/":
expressionResult.Value = (ushort)(left.Value / right.Value);
break;
case "+":
expressionResult.Value = (ushort)(left.Value + right.Value);
break;
case "-":
expressionResult.Value = (ushort)(left.Value - right.Value);
break;
case "<<":
expressionResult.Value = (ushort)(left.Value << right.Value);
break;
case ">>":
expressionResult.Value = (ushort)(left.Value >> right.Value);
break;
case "|":
expressionResult.Value = (ushort)(left.Value | right.Value);
break;
case "^":
expressionResult.Value = (ushort)(left.Value ^ right.Value);
break;
case "&":
expressionResult.Value = (ushort)(left.Value & right.Value);
break;
case "%":
expressionResult.Value = (ushort)(left.Value % right.Value);
break;
case "==":
expressionResult.Value = (ushort)(left.Value == right.Value ? 1 : 0);
break;
case "!=":
case "<>":
expressionResult.Value = (ushort)(left.Value != right.Value ? 1 : 0);
break;
case "<":
expressionResult.Value = (ushort)(left.Value < right.Value ? 1 : 0);
break;
case ">":
expressionResult.Value = (ushort)(left.Value > right.Value ? 1 : 0);
break;
case "<=":
expressionResult.Value = (ushort)(left.Value <= right.Value ? 1 : 0);
break;
case ">=":
expressionResult.Value = (ushort)(left.Value >= right.Value ? 1 : 0);
break;
case "===":
expressionResult.Value = (ushort)(operands[0].ToLower().Trim() == operands[2].ToLower().Trim() ? 1 : 0);
break;
case "!==":
expressionResult.Value = (ushort)(operands[0].ToLower().Trim() != operands[2].ToLower().Trim() ? 1 : 0);
break;
case "&&":
expressionResult.Value = (ushort)(left.Value > 0 && right.Value > 1 ? 1 : 0);
break;
case "||":
expressionResult.Value = (ushort)(left.Value > 0 || right.Value > 1 ? 1 : 0);
break;
case "^^":
expressionResult.Value = (ushort)(left.Value > 0 ^ right.Value > 1 ? 1 : 0); // between boolean operators, ^ is ^^ in C#
break;
default:
expressionResult.Successful = false;
return(expressionResult);
}
return(expressionResult);
}
