/// <summary>
/// Tests if the expression will evaluate False with any combination of remaining inputs
/// </summary>
/// <returns>true if all possible combinations result in a False evaluation</returns>
/// <remarks>
/// This determines if the search for operands may be halted before the end of the list.
/// For example, the expression 'a AND b' can be halted if 'a' is false because it does not
/// matter what 'b' is. Conversely, the expression 'a OR b' cannot be halted if 'a' is false
/// since 'b' can be true. Even if the expression is known to be True before evaluating all
/// the operands, processing operands should continue to find all the matches in the remaining
/// operands.
/// </remarks>
public bool IsShortCircuitFalse()
{
var savedState = Operands.Select(o => o.EvaluatedResult).ToList();
List <List <bool> > values = new List <List <bool> >();
for (int idx = 0; idx < Math.Pow(2, Operands.Count); idx++)
{
values.Add(new List <bool>());
string binary = Convert.ToString(idx, 2).PadLeft(Operands.Count(), '0');
for (int jdx = 0; jdx < Operands.Count; jdx++)
{
var b = binary[jdx];
values[idx].Add(b != '0');
}
}
EvaluationResult result = EvaluationResult.Undetermined;
foreach (var row in values)
{
for (int col = 0; col < row.Count; col++)
{
if (!Operands[col].EvaluatedResult.HasValue)
{
Operands[col].EvaluatedResult = row[col];
}
}
EvaluationResult rowResult = EvaluateExpression(false) ? EvaluationResult.True : EvaluationResult.False;
// restore original state
for (int col = 0; col < Operands.Count; col++)
{
Operands[col].EvaluatedResult = savedState[col];
}
if (result == EvaluationResult.Undetermined)
{
result = rowResult;
}
else if (result != rowResult)
{
return(false);
}
}
return(result == EvaluationResult.False);
}
protected override void Compile(Program program)
{
if (Operands[0].OperandType == OperandType.Direct)
{
throw new ArgumentException();
}
var w = Operands.ToW();
if (Operands.Count(x => x.Value == "al" || x.Value == "ax") == 1)
{
var d = Operands[0].OperandType == OperandType.Memory ? 1 : 0;
BinaryCode.AddBits(1, 0, 1, 0, 0, 0, d, w);
var inMemoryOperand = Operands.First(x => x.OperandType == OperandType.Memory);
var reference = program.Labels[inMemoryOperand.Value];
BinaryCode.AddBytes(reference.InReverseByteOrder(program.ReferenceSize));
program.ObjectFile.SegmentsBlock.CodeSegment.AddReference(
new BinaryCode(0xC4)
.AddBytes((Address - program.DataSize + 1 - reference).InReverseByteOrder(1))
.AddBytes(0x14, 0x01, 0x02));
}
else if (Operands[0].OperandType == OperandType.Register)
{
if (Operands[1].OperandType == OperandType.Direct)
{
BinaryCode.AddBits(1, 0, 1, 1, w);
BinaryCode.AddBits(RegistersManager.GetCode(Operands[0].Value));
BinaryCode.AddBytes(int.Parse(Operands[1].Value).InReverseByteOrder(w + 1));
}
else if (Operands[1].OperandType == OperandType.Register)
{
BinaryCode.AddBits(1, 0, 0, 0, 1, 0, 1, w, 1, 1);
BinaryCode.AddBits(RegistersManager.GetCode(Operands[0].Value));
BinaryCode.AddBits(RegistersManager.GetCode(Operands[1].Value));
}
}
else
{
throw new NotSupportedException();
}
}
public bool TryParse(string input)
{
ParserState = ParserErrorState.None;
bool result = true;
try
{
BooleanTokenizer tokenizer = new BooleanTokenizer();
var list = tokenizer.Tokenize(input).ToList();
result = BuildExpression(list);
PostfixTokens = InfixToPostfix(list).ToList();
PostfixExpression = string.Join(" ", PostfixTokens.Select(t => t.Value));
int numUnaryOperators = PostfixTokens.Where(t => t.TokenType == TokenType.NOT).Count();
int numBinaryOperators = PostfixTokens.Where(t => TokenType.Operator.HasFlag(t.TokenType)).Count() - numUnaryOperators;
int numOperands = Operands.Count();
if (numBinaryOperators < numOperands - 1)
{
ParserState = ParserErrorState.MissingOperator;
result = false;
}
}
catch (InvalidStateException ex)
{
ParserState = ex.State;
result = false;
}
catch (Exception ex)
{
string message = ex.Message;
result = false;
ParserState = ParserErrorState.UnknownError;
}
return(result);
}
/// <summary>
/// Return true if this node has operands, otherwise return false
/// </summary>
/// <returns></returns>
public bool HasOperands()
{
return(Operands.Count() > 0);
}