IExpression ParseMultiplicativeExpression()
{
var left = ParseUnaryExpression();
while (true)
{
if (SkipIf("*"))
{
var right = ParseUnaryExpression();
left = new BinaryOperation(left, OperationType.Multiplication, right);
}
else if (SkipIf("/"))
{
var right = ParseUnaryExpression();
left = new BinaryOperation(left, OperationType.Division, right);
}
else if (SkipIf("%"))
{
var right = ParseUnaryExpression();
left = new BinaryOperation(left, OperationType.Remainder, right);
}
else
{
break;
}
}
return(left);
}
public object Visit(BinaryOperation expression)
{
var left = Calc(expression.Left);
var right = Calc(expression.Right);
if (left is null || right is null)
{
switch (expression.Operation)
{
case OperationType.Equality:
return(left == right);
}
throw new Exception("Неизвестная операция");
}
if (left is int && right is int)
{
int leftInt = (int)left;
int rightInt = (int)right;
switch (expression.Operation)
{
case OperationType.Addition:
return(leftInt + rightInt);
case OperationType.Subtraction:
return(leftInt - rightInt);
case OperationType.Multiplication:
return(leftInt * rightInt);
case OperationType.Division:
return(leftInt / rightInt);
case OperationType.Remainder:
return(leftInt % rightInt);
case OperationType.Equality:
return(leftInt == rightInt);
case OperationType.Relation:
return(leftInt < rightInt);
}
throw new Exception("Неизвестная операция");
}
if (left is bool && right is bool)
{
bool leftBool = (bool)left;
bool rightBool = (bool)right;
switch (expression.Operation)
{
case OperationType.Equality:
return(leftBool == rightBool);
case OperationType.Relation:
return(!leftBool && rightBool);
}
throw new Exception("Неизвестная операция");
}
throw new Exception("Неверный тип операндов");
}
IExpression ParseEqualityExpression()
{
var left = ParseRelationalExpression();
while (true)
{
if (SkipIf("=="))
{
var right = ParseRelationalExpression();
left = new BinaryOperation(left, OperationType.Equality, right);
}
else
{
break;
}
}
return(left);
}
IExpression ParseRelationalExpression()
{
var left = ParseAdditiveExpression();
while (true)
{
if (SkipIf("<"))
{
var right = ParseAdditiveExpression();
left = new BinaryOperation(left, OperationType.Relation, right);
}
else
{
break;
}
}
return(left);
}
IExpression ParseAdditiveExpression()
{
var left = ParseMultiplicativeExpression();
while (true)
{
if (SkipIf("+"))
{
var right = ParseMultiplicativeExpression();
left = new BinaryOperation(left, OperationType.Addition, right);
}
else if (SkipIf("-"))
{
var right = ParseMultiplicativeExpression();
left = new BinaryOperation(left, OperationType.Subtraction, right);
}
else
{
break;
}
}
return(left);
}