public static IElement Parse(IReadOnlyList <Token> tokens)
{
bool isLHSPresent = false;
var binaryOperation = new BinaryOperation();
for (int i = 0; i < tokens.Count; i++)
{
switch (tokens[i].TokenType)
{
case Token.Type.Lparen:
int j = i + 1;
for (; j < tokens.Count; j++)
{
if (tokens[j].TokenType == Token.Type.Rparen)
{
break;
}
}
var subExp = tokens.Skip(i).Take(j - i - 1).ToList();
var element = Parse(subExp);
if (isLHSPresent)
{
binaryOperation.RHS = element;
}
else
{
binaryOperation.LHS = element;
isLHSPresent = true;
}
break;
case Token.Type.Addition:
binaryOperation.OperationType = BinaryOperation.Operation.Addition;
break;
case Token.Type.Subtraction:
binaryOperation.OperationType = BinaryOperation.Operation.Subtraction;
break;
case Token.Type.Number:
if (isLHSPresent)
{
binaryOperation.RHS = new Integer(int.Parse(tokens[i].Text));
}
else
{
binaryOperation.LHS = new Integer(int.Parse(tokens[i].Text));
isLHSPresent = true;
}
break;
default:
break;
}
}
return(binaryOperation);
}
static IElement Parse(IReadOnlyList <Token> tokens)
{
var result = new BinaryOperation();
bool haveLeft = false;
for (int i = 0; i < tokens.Count; i++)
{
var token = tokens[i];
switch (token.MyType)
{
case Token.Type.Integer:
var integer = new Integer(int.Parse(token.Text));
if (!haveLeft)
{
result.Left = integer;
haveLeft = true;
}
else
{
result.Right = integer;
}
break;
case Token.Type.Plus:
result.MyType = BinaryOperation.Type.Addition;
break;
case Token.Type.Minus:
result.MyType = BinaryOperation.Type.Subtraction;
break;
case Token.Type.LParentheses:
int j = i;
for (; j < tokens.Count; j++)
{
if (tokens[j].MyType == Token.Type.RParentheses)
{
break;
}
}
var subexpression = tokens.Skip(i + 1).Take(j - i - 1).ToList();
var element = Parse(subexpression);
if (!haveLeft)
{
result.Left = element;
haveLeft = true;
}
else
{
result.Right = element;
}
i = j;
break;
}
}
return(result);
}
private IElement Parse(IReadOnlyList <Token> tokens)
{
var result = new BinaryOperation();
if (tokens.Count == 1)
{
return(new Number(int.Parse(tokens[0].Text)));
}
result.Left = new Number(int.Parse(tokens[0].Text));
result.OperationType = (tokens[1].SignType == Sign.Plus) ?
BinaryOperation.Type.Add :
BinaryOperation.Type.Sub;
result.Right = new Number(int.Parse(tokens[2].Text));
var newTokens = new List <Token>();
newTokens.Add(new Token(Sign.Number, result.Value.ToString()));
newTokens.AddRange(tokens.Skip(3));
return(Parse(newTokens));
}
static IElement Parse(IReadOnlyList <Token> tokens)
{
var result = new BinaryOperation();
bool haveLeftSide = false;
for (int i = 0; i < tokens.Count; i++)
{
var token = tokens[i];
switch (token.MyType)
{
case Enums.Type.Integer:
var integer = new Integer(int.Parse(token.Text));
if (!haveLeftSide)
{
result.Left = integer;
haveLeftSide = true;
}
else
{
result.Right = integer;
}
break;
case Enums.Type.Plus:
result.MyType = OperationType.Addition;
break;
case Enums.Type.Minus:
result.MyType = OperationType.Substraction;
break;
case Enums.Type.Lparen:
int j = i;
for (; j < tokens.Count; ++j)
{
if (tokens[j].MyType == Enums.Type.Rparen)
{
break;
}
}
var subExpression = tokens.Skip(i + 1).Take(j - i - 1).ToList();
var element = Parse(subExpression);
if (!haveLeftSide)
{
result.Left = element;
haveLeftSide = true;
}
else
{
result.Right = element;
}
i = j;
break;
default:
throw new ArgumentOutOfRangeException();
}
}
return(result);
}
private static IElement Parse(IReadOnlyList <Token> tokens)
{
var result = new BinaryOperation();
var haveLhs = false;
for (var i = 0; i < tokens.Count; i++)
{
var token = tokens[i];
// look at the type of token
switch (token.MyType)
{
case Token.Type.Integer:
var integer = new Integer(int.Parse(token.Text));
if (!haveLhs)
{
result.Left = integer;
haveLhs = true;
}
else
{
result.Right = integer;
}
break;
case Token.Type.Plus:
result.MyType = BinaryOperation.Type.Addition;
break;
case Token.Type.Minus:
result.MyType = BinaryOperation.Type.Subtraction;
break;
case Token.Type.Lparen:
var j = i;
for (; j < tokens.Count; ++j)
{
if (tokens[j].MyType == Token.Type.Rparen)
{
break; // found it!
}
}
// process subexpression w/o opening (
var subexpression = tokens.Skip(i + 1).Take(j - i - 1).ToList();
var element = Parse(subexpression);
if (!haveLhs)
{
result.Left = element;
haveLhs = true;
}
else
{
result.Right = element;
}
i = j; // advance
break;
case Token.Type.Rparen:
break;
default:
throw new ArgumentOutOfRangeException();
}
}
return(result);
}
