public BinaryTree(string expression)
{
#region Initialization
Root = new BinaryNode
(
value: null,
oper: null,
parent: null,
left: null,
right: null
);
char symbol = '\0';
long? number = null;
BinaryNode current = Root;
BinaryNode subOperationRoot = null;
CharEnumerator charEnumerator = expression.GetEnumerator();
#endregion
while (charEnumerator.MoveNext())
{
symbol = charEnumerator.Current;
#region Whitespace
if (symbol == ' ')
{
// Skip white space
continue;
}
#endregion
#region Numeral
// If numeral, continue to read all consecutive numerals
if (char.IsNumber(symbol))
{
number = number.Append(symbol);
continue;
}
#endregion
#region Not numeral
// Symbol is not a numeral; add number to tokens
if (number.HasValue)
{
if (current.Value != null)
{
throw new MathExpressionException("Consecutive operands.");
}
current.Value = new Fraction((long)number);
number = null;
}
#endregion
#region Sub-expression '('
if (symbol == '(')
{
// Read the sub-expression
StringBuilder stringBuilder = new StringBuilder();
Stack <char> stack = new Stack <char>();
while (charEnumerator.MoveNext())
{
char subSymbol = charEnumerator.Current;
if (subSymbol == '(')
{
stack.Push(')');
}
else if (subSymbol == ')')
{
if (stack.Any())
{
stack.Pop();
}
else
{
break;
}
}
stringBuilder.Append(subSymbol);
}
if (stack.Any())
{
throw new MathExpressionException("Unmatched paranthesis.");
}
BinaryTree subTree = new BinaryTree(stringBuilder.ToString());
current.Value = subTree.Root.Value;
current.Operator = subTree.Root.Operator;
current.Left = subTree.Root.Left;
current.Right = subTree.Root.Right;
continue;
}
#endregion
#region Operator '+' '-'
if (symbol == '+' || symbol == '-')
{
BinaryNode newBinaryNode = new BinaryNode
(
value: null,
oper: new Operator(symbol),
parent: null,
left: Root,
right: null
);
newBinaryNode.Right = new BinaryNode
(
value: null,
oper: null,
parent: newBinaryNode,
left: null,
right: null
);
Root.Parent = newBinaryNode;
Root = newBinaryNode;
current = newBinaryNode.Right;
subOperationRoot = null;
continue;
}
#endregion
#region Operator '*' '/'
if (symbol == '*' || symbol == '/')
{
BinaryNode newBinaryNode;
BinaryNode newBinaryNodeleft = subOperationRoot ?? current;
newBinaryNode = new BinaryNode
(
value: null,
oper: new Operator(symbol),
parent: newBinaryNodeleft.Parent,
left: newBinaryNodeleft,
right: null
);
if (newBinaryNodeleft == Root)
{
Root = newBinaryNode;
}
else
{
newBinaryNodeleft.Parent.Right = newBinaryNode;
}
newBinaryNode.Right = new BinaryNode
(
value: null,
oper: null,
parent: newBinaryNode,
left: null,
right: null
);
current.Parent = newBinaryNode;
current = newBinaryNode.Right;
subOperationRoot = newBinaryNode;
continue;
}
#endregion
throw new MathExpressionException("Unrecognized symbol.");
}
if (number is null && symbol != '(')
{
throw new MathExpressionException("Missing opperand.");
}
if (number != null)
{
current.Value = new Fraction((long)number);
}
}
public BinaryNode(Fraction?value, Operator oper, BinaryNode parent, BinaryNode left, BinaryNode right)
{
Value = value;
Operator = oper;
Parent = parent;
Left = left;
Right = right;
}
