//a/c + b/c = (a+b)/c
public static ExpressionBase AddFractionWithCommonDenominatorRule(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a sum.
VariadicOperatorExpression variadicExpression = expression as VariadicOperatorExpression;
if (variadicExpression != null && variadicExpression.Type == OperatorType.Add)
{
BinaryOperatorExpression binaryOperand;
List<ExpressionBase> terms = new List<ExpressionBase>();
ExpressionBase commonDenominator = null;
//Foreach operand in sum.
foreach (ExpressionBase operand in variadicExpression)
{
//If operand is a fraction.
binaryOperand = operand as BinaryOperatorExpression;
if (binaryOperand != null && binaryOperand.Type == OperatorType.Divide)
{
//If operand is the first fraction in sum
if (terms.Count == 0)
{
//Add numerator to list of numerators.
terms.Add(binaryOperand.Left.Clone());
//Set commonDenominator to operand's denominator.
commonDenominator = binaryOperand.Right.Clone();
}
else if (commonDenominator == binaryOperand.Right)
{
//Add fraction's numerator to list if its denominator equals commenDenominator.
terms.Add(binaryOperand.Left.Clone());
}
else
{
//Return null if an fraction's denominator does not equals commenDenominator.
return null;
}
}
else
{
//Return if operand is not a fraction.
return null;
}
}
if (terms.Count > 1)
{
//Initialize sum of all fractions' numerators.
VariadicOperatorExpression SuggestionNumerator = new VariadicOperatorExpression(OperatorType.Add, terms[0], terms[1]);
SuggestionNumerator.Add(terms.Skip(2).ToList());
//Return fraction with sum of all fractions' numerators and with their common denominator.
return new BinaryOperatorExpression(SuggestionNumerator, commonDenominator, OperatorType.Divide);
}
}
return null;
}
public List<Identity> GetIdentities(List<ExpressionBase> selection)
{
var identities = new List<Identity>();
if (selection.Count == 0)
{
return identities;
}
ExpressionBase commonParent = GetCommonParent(selection);
if (commonParent is VariadicOperatorExpression)
{
VariadicOperatorExpression variadicParent = commonParent as VariadicOperatorExpression;
List<ExpressionBase> operandsLeftOfSelection = new List<ExpressionBase>();
List<ExpressionBase> operandsRightOfSelection = new List<ExpressionBase>();
List<ExpressionBase> selectedOperands = new List<ExpressionBase>();
foreach (ExpressionBase operand in variadicParent)
{
if (operand.Selected == false && operand.GetNodesRecursive().Any((n) => n.Selected == true) == false)
{
if (selectedOperands.Count == 0)
{
operandsLeftOfSelection.Add(operand);
}
else
{
operandsRightOfSelection.Add(operand);
}
}
else
{
selectedOperands.Add(operand);
}
}
VariadicOperatorExpression toBeReplaced = new VariadicOperatorExpression(variadicParent.Type, selectedOperands[0].Clone(), selectedOperands[1].Clone());
List<ExpressionBase> toBeReplacedSelection = new List<ExpressionBase>();
foreach (ExpressionBase operand in selectedOperands.Skip(2))
{
toBeReplaced.Add(operand.Clone());
}
toBeReplacedSelection = toBeReplaced.GetNodesRecursive().Where((n) => n.Selected == true).ToList();
foreach (ExpressionRule rule in rules)
{
ExpressionBase suggestion = rule(toBeReplaced, toBeReplacedSelection);
if (identities.Select((i) => i.Suggestion).Contains(suggestion) == false && suggestion != commonParent)
{
if (suggestion != null)
{
ExpressionBase result;
if (variadicParent.Count == selectedOperands.Count)
{
result = suggestion;
}
else
{
VariadicOperatorExpression variadicResult = new VariadicOperatorExpression(variadicParent.Type, new NumericExpression(-1), new NumericExpression(-1));
variadicResult.Add(operandsLeftOfSelection.Select((o) => o.Clone()).ToList());
variadicResult.Add(WrapInDelimiterIfNeccessary(suggestion.Clone(), variadicResult));
variadicResult.Add(operandsRightOfSelection.Select((o) => o.Clone()).ToList());
variadicResult.RemoveAt(0);
variadicResult.RemoveAt(0);
result = variadicResult;
}
identities.Add(new Identity(suggestion, WrapInDelimiterIfNeccessary(result, commonParent.Parent)));
}
}
}
}
else
{
foreach (ExpressionRule rule in rules)
{
ExpressionBase suggestion = WrapInDelimiterIfNeccessary(rule(commonParent, selection), commonParent.Parent);
if (identities.Select((i) => i.Suggestion).Contains(suggestion) == false && suggestion != commonParent)
{
if (suggestion != null)
{
identities.Add(new Identity(suggestion, suggestion));
}
}
}
}
return identities;
}
public ExpressionBase Parse(List<Token> postFix)
{
var stack = new ExpressionStack();
ExpressionBase root = null;
ExpressionBase left = null;
ExpressionBase right = null;
foreach (var token in postFix)
{
switch (token.Type)
{
case TokenType.Function:
root = new FunctionExpression(stack.Pop(), (string)token.Data);
stack.Push(root);
break;
case TokenType.Delimiter:
switch (token.Data.ToString())
{
case "()":
root = new DelimiterExpression(stack.Pop());
stack.Push(root);
break;
case "{}":
root = stack.Pop();
stack.Push(root);
break;
}
break;
case TokenType.Number:
root = new NumericExpression(int.Parse(token.Data.ToString()));
stack.Push(root);
break;
case TokenType.Constant:
root = new ConstantExpression((ConstantType)token.Data);
stack.Push(root);
break;
case TokenType.Variable:
root = new VariableExpression((string)token.Data);
stack.Push(root);
break;
case TokenType.Operator:
switch (token.Data.ToString())
{
case "~":
root = new UnaryMinusExpression(stack.Pop());
stack.Push(root);
break;
case "+":
right = stack.Pop();
left = stack.Pop();
if (left is VariadicOperatorExpression && (left as VariadicOperatorExpression).Type == OperatorType.Add)
{
(left as VariadicOperatorExpression).Add(right);
root = left;
stack.Push(root);
}
else
{
root = new VariadicOperatorExpression(OperatorType.Add, left, right);
stack.Push(root);
}
break;
case "-":
if (this.TreatMinusAsUnaryMinusInVariadicPlus)
{
right = new UnaryMinusExpression(stack.Pop());
left = stack.Pop();
if (left is VariadicOperatorExpression && (left as VariadicOperatorExpression).Type == OperatorType.Add)
{
(left as VariadicOperatorExpression).Add(right);
root = left;
stack.Push(root);
}
else
{
root = new VariadicOperatorExpression(OperatorType.Add, left, right);
stack.Push(root);
}
}
else // treat it at binary operator
{
right = stack.Pop();
left = stack.Pop();
root = new BinaryOperatorExpression(left, right, OperatorType.Subtract);
stack.Push(root);
}
break;
case "*":
right = stack.Pop();
left = stack.Pop();
if (left is VariadicOperatorExpression && (left as VariadicOperatorExpression).Type == OperatorType.Multiply)
{
(left as VariadicOperatorExpression).Add(right);
root = left;
stack.Push(root);
}
else
{
root = new VariadicOperatorExpression(OperatorType.Multiply, left, right);
stack.Push(root);
}
break;
case "/":
right = stack.Pop();
left = stack.Pop();
root = new BinaryOperatorExpression(left, right, OperatorType.Divide);
stack.Push(root);
break;
case "^":
right = stack.Pop();
left = stack.Pop();
root = new BinaryOperatorExpression(left, right, OperatorType.Power);
stack.Push(root);
break;
}
break;
}
}
return root;
}
public override ExpressionBase Clone()
{
if (Count < 2)
throw new InvalidOperationException("Tried to clone invalid VariadicExpression.");
var expression = new VariadicOperatorExpression(Type, this[0].Clone(), this[1].Clone()) { Selected = Selected };
foreach (var expr in this.Skip(2))
{
expression.Add(expr.Clone());
}
return expression;
}
//{a*b}/c = a/c * b/c
public static ExpressionBase SplittingFractions(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a fraction. e.g. {a*b}/c
BinaryOperatorExpression binaryExpression = expression as BinaryOperatorExpression;
if (binaryExpression != null && binaryExpression.Type == OperatorType.Divide)
{
//If the fraction's numerator is a sum e.g. a*b in fraction {a*b}/c
VariadicOperatorExpression numerators = binaryExpression.Left.Clone() as VariadicOperatorExpression;
if (numerators != null && numerators.Type == OperatorType.Add && numerators.Count > 1)
{
List<ExpressionBase> fractionList = new List<ExpressionBase>();
//Foeach operand in the numerator's sum. e.g. a and b in fraction {a*b}/c
foreach (var i in numerators)
{
//Initialize a fraction with the operand as numerator and add to list. e.g. a/c and b/c
fractionList.Add(new BinaryOperatorExpression(i, binaryExpression.Right.Clone(), OperatorType.Divide));
}
//Initialize and return the product of all the fractions in the list. e.g. a/c * b/c
VariadicOperatorExpression suggestion = new VariadicOperatorExpression(OperatorType.Add, fractionList[0], fractionList[1]);
foreach (var i in fractionList.Skip(2))
{
suggestion.Add(i);
}
return suggestion;
}
}
return null;
}
//(a*b)^c = a^c * b^c
public static ExpressionBase ReverseCommonPowerParenthesisRule(ExpressionBase expression, List<ExpressionBase> selection)
{
List<ExpressionBase> itemsInParenthesis = new List<ExpressionBase>();
VariadicOperatorExpression suggestion;
//If expression is a power
var binaryExpression = expression as BinaryOperatorExpression;
if (binaryExpression != null && binaryExpression.Type == OperatorType.Power)
{
var commonparrent = binaryExpression.Right.Clone();
//If power's base is a parenthesis
if (binaryExpression.Left is DelimiterExpression)
{
var delimiterExpression = binaryExpression.Left as DelimiterExpression;
//If the parenthesis' content is a product
if (delimiterExpression.Expression is VariadicOperatorExpression)
{
var variadicExpression = delimiterExpression.Expression.Clone() as VariadicOperatorExpression;
if (variadicExpression.Type == OperatorType.Multiply)
{
//Raise every operand to the power's exponent.
foreach (var item in variadicExpression)
{
itemsInParenthesis.Add(new BinaryOperatorExpression(item, commonparrent, OperatorType.Power));
}
//Initialize and reutrn product of exponents
suggestion = new VariadicOperatorExpression(OperatorType.Multiply, itemsInParenthesis[0].Clone(), itemsInParenthesis[1].Clone());
if (itemsInParenthesis.Count > 2)
{
foreach (var item in itemsInParenthesis.Skip(2))
{
suggestion.Add(item.Clone());
}
return suggestion;
}
else
{
return suggestion;
}
}
}
}
}
return null;
}
//a*b+a*c = (b+c)*a
//a*b-a*c = (b-c)*a
public static ExpressionBase ProductParenthesis(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a sum. e.g. a*b*c - a*b*d
VariadicOperatorExpression sum = expression as VariadicOperatorExpression;
if (sum != null && sum.Type == OperatorType.Add)
{
List<ExpressionBase> suggestionSum = new List<ExpressionBase>();
List<ExpressionBase> commonProductOperands = new List<ExpressionBase>();
//Foreach operand in sum e.g. a*b*c and a*b*d
foreach (var actualOperand in sum)
{
ExpressionBase operand;
bool negative;
//If operand is unary minus take its operand and set negative = true. e.g. -a*b*d => operand = a*b*d, negative = true
UnaryMinusExpression minus = actualOperand as UnaryMinusExpression;
if (minus != null)
{
operand = minus.Expression;
negative = true;
}
else
{
operand = actualOperand;
negative = false;
}
List<ExpressionBase> selectedProductOperands = new List<ExpressionBase>() { operand };
List<ExpressionBase> nonSelectedProductOperands = new List<ExpressionBase>() { };
VariadicOperatorExpression product = operand as VariadicOperatorExpression;
//If operand in the sum is a product. e.g. a*b*d
if (product != null && product.Type == OperatorType.Multiply)
{
//Store all selected and nonselected operands in the product.
selectedProductOperands = product.Where((o) => (o.Selected == true || o.GetNodesRecursive().Any((n) => n.Selected))).ToList();
nonSelectedProductOperands = product.Where((o) => o.Selected == false && o.GetNodesRecursive().Any((n) => n.Selected) == false).ToList();
}
bool allEqual = true;
//Determine if all selected operands of the product are equal and in same order to the commen product operands.
if (commonProductOperands.Count == 0 || commonProductOperands.Count == selectedProductOperands.Count)
{
for (int index = 0; index < commonProductOperands.Count; index++)
{
if (commonProductOperands[index] != selectedProductOperands[index])
{
allEqual = false;
}
}
}
else
{
return null;
}
//If all selected operands in the product are in the common products operands.
if (allEqual || commonProductOperands.Count == 0)
{
commonProductOperands = selectedProductOperands;
//If the whole operand of the sum is selected leave 1 or -1 at its placing when factor outside parenthesis.
if (nonSelectedProductOperands.Count == 0)
{
suggestionSum.Add(negative ? ToNumeric(-1) : ToNumeric(1));
}
else if (nonSelectedProductOperands.Count == 1)
{
//If one operand of the product is not selected leave it when factorize the rest outside.
ExpressionBase clone = nonSelectedProductOperands[0].Clone();
suggestionSum.Add(negative ? new UnaryMinusExpression(clone) : clone);
}
else
{
//If two or more operands of the product is not selected leave these when factorize the rest outside.
VariadicOperatorExpression nonSelectedProduct = new VariadicOperatorExpression(OperatorType.Multiply, nonSelectedProductOperands[0].Clone(), nonSelectedProductOperands[1].Clone());
nonSelectedProduct.Add(nonSelectedProductOperands.Skip(2).Select((o) => o.Clone()).ToList());
suggestionSum.Add(negative ? (ExpressionBase)new UnaryMinusExpression(nonSelectedProduct) : nonSelectedProduct);
}
}
else
{
//If two operands in the sum has two different selections return null
return null;
}
}
//Return product where the common product selection is factorized outside a parenthesis. e.g. (c - d)*a*b
VariadicOperatorExpression sumExpression = new VariadicOperatorExpression(OperatorType.Add, suggestionSum[0], suggestionSum[1]);
sumExpression.Add(suggestionSum.Skip(2).ToList());
VariadicOperatorExpression suggestion = new VariadicOperatorExpression(OperatorType.Multiply, sumExpression, new NumericExpression(-1));
suggestion.Add(commonProductOperands.Select((o) => o.Clone()).ToList());
suggestion.RemoveAt(1);
return suggestion;
}
return null;
}
// a/b * c/d = {a*c}/{b*d}
public static ExpressionBase ProductOfFractions(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is product if two or more operands
VariadicOperatorExpression variadicExpression = expression as VariadicOperatorExpression;
if (variadicExpression != null && variadicExpression.Type == OperatorType.Multiply && variadicExpression.Count >= 2)
{
List<ExpressionBase> listOfNumerators = new List<ExpressionBase>();
List<ExpressionBase> listOfDenominators = new List<ExpressionBase>();
//Foreach operand in product
foreach (ExpressionBase operand in variadicExpression)
{
//If operand is a fraction
BinaryOperatorExpression binaryExpression = operand as BinaryOperatorExpression;
if(binaryExpression != null && binaryExpression.Type == OperatorType.Divide)
{
//Add numerator and donimator to list
listOfNumerators.Add(binaryExpression.Left.Clone());
listOfDenominators.Add(binaryExpression.Right.Clone());
}
else
{
//If operands i not a fraction return null
return null;
}
}
//Convert list to product of numerators
VariadicOperatorExpression suggestionNumerator = new VariadicOperatorExpression(OperatorType.Multiply, listOfNumerators[0], listOfNumerators[1]);
foreach (var item in listOfNumerators.Skip(2))
{
suggestionNumerator.Add(item);
}
//Convert list to product of denominators
VariadicOperatorExpression suggestionDenominator = new VariadicOperatorExpression(OperatorType.Multiply, listOfDenominators[0], listOfDenominators[1]);
foreach (var item in listOfDenominators.Skip(2))
{
suggestionDenominator.Add(item);
}
//Return fraction with product of numerators and denominators
return new BinaryOperatorExpression(suggestionNumerator, suggestionDenominator, OperatorType.Divide);
}
return null;
}
// a*{b/c} = {a*b}/c
public static ExpressionBase ProductOfConstantAndFraction(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a product with to operands
var variadicExpression = expression as VariadicOperatorExpression;
if (variadicExpression != null && variadicExpression.Type == OperatorType.Multiply && variadicExpression.Count == 2)
{
BinaryOperatorExpression fraction = null;
ExpressionBase other = null;
//Find which operand is a fraction
if ((fraction = variadicExpression[0] as BinaryOperatorExpression) != null && fraction.Type == OperatorType.Divide)
{
other = variadicExpression[1];
}
else if ((fraction = variadicExpression[1] as BinaryOperatorExpression) != null && fraction.Type == OperatorType.Divide)
{
other = variadicExpression[0];
}
else
{
//Return null of non of the operands is a fraction
return null;
}
//Multiply numerator with other operand
VariadicOperatorExpression numerators = new VariadicOperatorExpression(OperatorType.Multiply, fraction.Left.Clone(), other.Clone());
//Return fraction
BinaryOperatorExpression suggestion = new BinaryOperatorExpression(numerators.Clone(), fraction.Right.Clone(), OperatorType.Divide);
return suggestion;
}
return null;
}
//a/b = a*b^-1
public static ExpressionBase FractionToProductRule(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression a fraction. e.g. a/b
BinaryExpression fraction = expression as BinaryExpression;
if (fraction != null && fraction.Type == OperatorType.Divide)
{
//Convert denominator to power of -1. b => b^-1
ExpressionBase exponent = new BinaryOperatorExpression(
fraction.Right.Clone(),
new UnaryMinusExpression(new NumericExpression(1)),
OperatorType.Power
);
//Return product of numerator and power. a*b^-1
ExpressionBase suggestion = new VariadicOperatorExpression(
OperatorType.Multiply,
fraction.Left.Clone(),
exponent
);
return suggestion;
}
else
{
return null;
}
}
//-a = (-1)*a
public static ExpressionBase FactorizeUnaryMinus(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is unary minus
var unaryMinusExpression = expression as UnaryMinusExpression;
if (unaryMinusExpression != null)
{
//Return product of operand and (-1)
var numericExpression = new NumericExpression(1);
var suggestion = new VariadicOperatorExpression(OperatorType.Multiply, new UnaryMinusExpression(numericExpression), unaryMinusExpression.Expression.Clone());
return suggestion;
}
return null;
}
//6 = 2*3
public static ExpressionBase FactorizationRule(ExpressionBase expression, List<ExpressionBase> selection)
{
VariadicOperatorExpression suggestion;
//If expression is a number
if (expression is NumericExpression && expression != null)
{
var numericExpression = selection[0] as NumericExpression;
var n = numericExpression.Number;
//Find integers a != 1 and b != 1 such that n = a*b
for (int count = 2; count < n; count++)
{
if (n % count == 0)
{
NumericExpression a = new NumericExpression(count);
NumericExpression b = new NumericExpression(n / count);
//Return product of a and b
suggestion = new VariadicOperatorExpression(OperatorType.Multiply, a, b);
return suggestion;
}
}
}
return null;
}
//a^n = a*a*...*a where n is an integer.
public static ExpressionBase ExponentToProductRule(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a power.
BinaryOperatorExpression exponent = expression as BinaryOperatorExpression;
if (exponent != null && exponent.Type == OperatorType.Power)
{
//If exponent is a number.
NumericExpression numericExpression = exponent.Right as NumericExpression;
if (numericExpression != null)
{
int number = (int)numericExpression.Number;
if (number == 0)
{
//a^0 = 1
return new NumericExpression(1);
}
else if (number == 1)
{
//a^1 = a
return exponent.Left.Clone();
}
else if (number > 1)
{
//a^n = a*a*..*a
VariadicOperatorExpression result = new VariadicOperatorExpression(OperatorType.Multiply, exponent.Left.Clone(), exponent.Left.Clone());
for (int i = 2; i < number; i++)
{
result.Add(exponent.Left.Clone());
}
return result;
}
}
else
{
return null;
}
}
return null;
}
//a^n*a^m = a^{n+m}
public static ExpressionBase ExponentProduct(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a product. e.g. a*a^2
VariadicOperatorExpression product = expression as VariadicOperatorExpression;
if (product != null && product.Type == OperatorType.Multiply)
{
List<ExpressionBase> sum = new List<ExpressionBase>();
ExpressionBase commonBase = null;
//Foreach operand in product
foreach (var operand in product)
{
ExpressionBase operandLeft = operand;
ExpressionBase operandRight = new NumericExpression(1);
BinaryOperatorExpression power = operand as BinaryOperatorExpression;
if (power != null && power.Type == OperatorType.Power)
{
operandLeft = power.Left;
operandRight = power.Right;
}
//If operand's base equals commonBase.
if (operandLeft == commonBase || commonBase == null)
{
//Add operands exponent to sum.
commonBase = operandLeft;
sum.Add(operandRight.Clone());
}
else
{
return null;
}
}
if (sum.Count > 1)
{
//Return power with common base and sum of all operands' exponents.
VariadicOperatorExpression suggestionRight = new VariadicOperatorExpression(OperatorType.Add, sum[0], sum[1]);
suggestionRight.Add(sum.Skip(2).ToList());
return new BinaryOperatorExpression(commonBase, suggestionRight, OperatorType.Power);
}
}
return null;
}
//a^c * b^c = (a*b)^c
public static ExpressionBase CommonPowerParenthesisRule(ExpressionBase expression, List<ExpressionBase> selection)
{
//If expression is a product. e.g. a^c * b^c
VariadicOperatorExpression product = expression as VariadicOperatorExpression;
if (product != null && product.Type == OperatorType.Multiply)
{
ExpressionBase commonPower = null;
List<ExpressionBase> baseList = new List<ExpressionBase>();
//Foreach operand in product
foreach (ExpressionBase operand in product)
{
//If operand is a power
BinaryOperatorExpression power = operand as BinaryOperatorExpression;
if (power != null && power.Type == OperatorType.Power)
{
//If power's exponent equals the common exponent
if (power.Right == commonPower || commonPower == null)
{
//Add power's base to list
commonPower = power.Right;
baseList.Add(power.Left);
}
else
{
return null;
}
}
else
{
return null;
}
}
if (baseList.Count > 1)
{
//Initialize product of all bases in the list.
VariadicOperatorExpression resultProduct = new VariadicOperatorExpression(OperatorType.Multiply, baseList[0].Clone(), baseList[1].Clone());
resultProduct.Add(baseList.Skip(2).Select((b) => b.Clone()).ToList());
//return exponent with product as base and common exponent. e.g. (a*b)^c
BinaryOperatorExpression result = new BinaryOperatorExpression(resultProduct, commonPower.Clone(), OperatorType.Power);
return result;
}
}
return null;
}