public override BooleanExp Replace(char name, BooleanExp exp)
{
if (_name == name)
{
return(exp.Copy());
}
else
{
return(new VariableExp(_name));
}
}
public bool ParseBlocks(string input)
{
// [expression] opt ended by ";"
// (block)
// [(block) operator (block)]
// [(var op var) operator (var op (block))]
// [(var op var) operator (var op (op var))]
// var & op delimited by ' ' :
// [(str str str) str (str str (str str))]
// op is determined by:
// 1. Outside of any block
// 2. Item 1 if two items
// 3. Even # items if odd # items total
// 4. Error if even # items > 2
// var is determined by:
// Remainders in the lists
// Parse text into useable form
IBlockParser parser = new BlockCharParser(OPEN_TAG, CLOSE_TAG, DELIMITER);
Block expression;
if (parser.ValidateBalancedTags(input))
{
expression = new Block(input, parser);
Console.WriteLine(expression);
}
else
{
Console.WriteLine(parser.Log);
return(false);
}
// Create operations
BooleanExp operation = ParseOperators(expression);
// Create assignment context.
Dictionary <string, string> allAssignments = GetVariablesText(input, ASSIGNMENT_TRIGGER, ASSIGNMENT_OPERATOR);
Dictionary <VariableExp, bool> validAssignments = ConvertVariableAssignment(allAssignments);
Context context = new Context();
context = AssignVariables(validAssignments, context);
// Perform calculation
return(operation.Evaluate(context));
}
/// <summary>
/// Returns the boolean operator with the appropriate variable assignments.
/// </summary>
/// <param name="boolOperator"></param>
/// <param name="operand1"></param>
/// <param name="operand2"></param>
/// <returns></returns>
private BooleanExp GetOperator(string boolOperator, BooleanExp operand1, BooleanExp operand2 = null)
{
switch (boolOperator)
{
case AND:
return(new AndExp(operand1, operand2));
case NOT:
return(new NotExp(operand1));
case OR:
return(new OrExp(operand1, operand2));
default:
throw new InvalidOperationException("Boolean comparison operator is invalid: " + boolOperator);
}
}
private bool IsSubOperationComplete(string operatorItem, BooleanExp operand1, BooleanExp operand2)
{
if (IsOperatorWithSingularOperand(operatorItem) && operand1 != null)
{
return(true);
}
else if (!string.IsNullOrEmpty(operatorItem) &&
operand1 != null &&
operand2 != null)
{
return(true);
}
else
{
return(false);
}
}
public abstract BooleanExp Replace(char name, BooleanExp exp);
public override BooleanExp Replace(char name, BooleanExp exp)
{
return(new Constant(_value));
}
public override BooleanExp Replace(char name, BooleanExp exp)
{
return(new AndExp(
_operand1.Replace(name, exp),
_operand2.Replace(name, exp)));
}
public AndExp(BooleanExp op1, BooleanExp op2)
{
_operand1 = op1;
_operand2 = op2;
}
private BooleanExp ParseOperators(Block expression)
{
// Get list of blocks as strings
List <string> blocks = new List <string>();
foreach (Block block in expression.ChildBlocks)
{
blocks.Add(OPEN_TAG + block.ToString() + CLOSE_TAG);
}
BooleanExp operand1 = null;
BooleanExp operand2 = null;
string operatorItem = null;
int j = 0;
for (int i = 0; i < expression.ChildText.Count; i++)
{
string item = expression.ChildText[i];
if (item == ASSIGNMENT_TRIGGER)
{
break;
}
if (blocks.Count > j && item == blocks[j])
{
if (IsFirstOperand(operand1))
{
operand1 = ParseOperators(expression.ChildBlocks[j]);
}
else
{
operand2 = ParseOperators(expression.ChildBlocks[j]);
}
j++;
}
else if (IsOperator(item))
{
if (!string.IsNullOrEmpty(operatorItem))
{
throw new InvalidOperationException("Two operators cannot follow each other. Each operator must be separated by an operand. \n" +
"Operator '" + operatorItem + "' at item index " + i);
}
operatorItem = item;
}
else
{
if (IsFirstOperand(operand1))
{
operand1 = ConvertOperand(item);
}
else
{
operand2 = ConvertOperand(item);
}
}
// Assign and reset values if sub-operation is complete
if (IsSubOperationComplete(operatorItem, operand1, operand2))
{
operand1 = GetOperator(operatorItem, operand1, operand2);
operatorItem = null;
operand2 = null;
}
}
return(operand1);
}
private bool IsFirstOperand(BooleanExp operand1)
{
return(operand1 == null);
}
public NotExp(BooleanExp op1)
{
_operand1 = op1;
}