public ITruthTableRow Simplify(ITruthTableRow otherRow)
{
// Instead of creating a memory intense copy, we create a very simple row object
// that will only hold the truth values in each cell and a result.
int numberOfVariables = Cells.Length;
TruthTableRow simplifiedRow = new TruthTableRow(uniqueVariables, numberOfVariables);
simplifiedRow.Result = Result;
int numberOfDeferringValues = 0;
for (int i = 0; i < Cells.Length; i++)
{
if (Cells[i] != otherRow.Cells[i])
{
// Then we deal with a don't care variable, which we indicate by null.
simplifiedRow.Cells[i] = '*';
numberOfDeferringValues++;
if (numberOfDeferringValues > 1)
{
return(null);
}
}
else
{
simplifiedRow.Cells[i] = Cells[i];
}
}
return(simplifiedRow);
}
public string TableHeader()
{
string result = "";
for (int i = 0; i < propositionVariablesSet.Count; i++)
{
result += propositionVariablesSet[i] + TruthTableRow.GetPadding();
}
result += "v\n";
return(result);
}
public TruthTableRow Copy()
{
TruthTableRow rowCopy = new TruthTableRow(propositionRoot, uniqueVariables, Cells.Length);
for (int i = 0; i < Cells.Length; i++)
{
rowCopy.Cells[i] = Cells[i];
}
rowCopy.Result = Result;
return(rowCopy);
}
/// <summary>
/// Wrapper method that makes the initial call to CreateRowsRecursively with some basic
/// input parameters that do not change.
/// </summary>
private void CreateTruthTableRows()
{
TruthTableRow initialRow = new TruthTableRow(propositionRoot, propositionVariablesSet, propositionVariablesSet.Count);
if (initialRow.Cells.Length == 0)
{
// We had no variables and are dealing with one of the constants.
// return an empty row with only a result value.
initialRow.Calculate();
Rows.Add(initialRow);
}
else
{
CreateRowsRecursively(0, new char[] { '0', '1' }, initialRow);
}
}
/// <summary>
/// Recursive method that evaluates a true and false value for every unique variable,
/// exhausting all possible permutations and creating a row copy for every such row.
/// This row copy is then added to the collection of rows of this truth table object.
/// </summary>
/// <param name="index">The current index, starting at 0, and evaluating until the index is equal to the number of unique variables - 1</param>
/// <param name="truthSet">A constant set of the two boolean values false and true</param>
/// <param name="row">A truth table row object that holds the combination of truth values for the abstract proposition variables.</param>
private void CreateRowsRecursively(int index, char[] truthSet, TruthTableRow row)
{
// This is something we only have to execute if we have abstract proposition variables.
foreach (char truthValue in truthSet)
{
if (index == propositionVariablesSet.Count - 1)
{
// add row to the table's list of rows and return back to the calling environment
row.Cells[index] = truthValue;
TruthTableRow copy = row.Copy();
copy.Calculate(); // Required call to Calculate, otherwise the Result truth value can not be set :-(
// With the current recursive approach, only one row is constructed inside the wrapper method.
Rows.Add(copy);
}
else
{
// Not at the final variable so we add the cell into the row and call the method again.
row.Cells[index] = truthValue;
CreateRowsRecursively(index + 1, truthSet, row);
}
}
}
