private Expression ParseExpression()
{
bool negative = false;
Expression expression = null;
if (CurrentToken.Text == "-")
{
negative = true;
currentPosition++;
}
if (CurrentToken.TokenType == SelectorTokenType.Dimension || CurrentToken.Text == "n" || CurrentToken.Text == "-n")
{
string dimension = CurrentToken.Text;
int dim;
string negativeSecond = null;
Match m = Regex.Match(CurrentToken.Text, @"(\d+n)-(\d+)");
if (m.Success)
{
dimension = m.Groups[1].Value;
negativeSecond = m.Groups[2].Value;
}
if (int.TryParse(dimension.Substring(0, dimension.Length - 1), out dim) || CurrentToken.Text == "n" || CurrentToken.Text == "-n")
{
if (CurrentToken.Text == "n")
{
dim = 1;
}
else if (CurrentToken.Text == "-n")
{
dim = -1;
}
dim = negative ? dim * -1 : dim;
currentPosition++;
if (CurrentToken.TokenType == SelectorTokenType.Plus)
{
currentPosition++;
if (CurrentToken.TokenType == SelectorTokenType.Number)
{
//xn+b
int num;
if (int.TryParse(CurrentToken.Text, out num))
{
expression = new NumericExpression(dim, num);
}
else
{
//parse error
}
}
}
else if (negativeSecond != null)
{
//xn-b
int num;
if (int.TryParse(negativeSecond, out num))
{
expression = new NumericExpression(dim, -num);
currentPosition--;
}
else
{
//parse error
}
}
else if (CurrentToken.Text == ")")
{
expression = new NumericExpression(dim, 0);
currentPosition--;
}
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.Number)
{
//b
int num;
if (int.TryParse(CurrentToken.Text, out num))
{
expression = new NumericExpression(0, num * (negative ? -1 : 1));
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.Ident)
{
//odd or even
if (CurrentToken.Text == "odd")
{
expression = new OddExpression();
}
else if (CurrentToken.Text == "even")
{
expression = new OddExpression();
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.String)
{
string withoutQuotes = CurrentToken.Text.Substring(1, CurrentToken.Text.Length - 2);
if (CurrentToken.Text == "odd")
{
expression = new OddExpression();
}
else if (CurrentToken.Text == "even")
{
expression = new OddExpression();
}
else
{
//parse error
}
}
return expression;
}
private Expression ParseExpression()
{
bool negative = false;
Expression expression = null;
if (CurrentToken.Text == "-")
{
negative = true;
currentPosition++;
}
if (CurrentToken.TokenType == SelectorTokenType.Dimension || CurrentToken.Text == "n" || CurrentToken.Text == "-n")
{
string dimension = CurrentToken.Text;
int dim;
string negativeSecond = null;
Match m = Regex.Match(CurrentToken.Text, @"(\d+n)-(\d+)");
if (m.Success)
{
dimension = m.Groups[1].Value;
negativeSecond = m.Groups[2].Value;
}
if (int.TryParse(dimension.Substring(0, dimension.Length - 1), out dim) || CurrentToken.Text == "n" || CurrentToken.Text == "-n")
{
if (CurrentToken.Text == "n")
{
dim = 1;
}
else if (CurrentToken.Text == "-n")
{
dim = -1;
}
dim = negative ? dim * -1 : dim;
currentPosition++;
if (CurrentToken.TokenType == SelectorTokenType.Plus)
{
currentPosition++;
if (CurrentToken.TokenType == SelectorTokenType.Number)
{
//xn+b
int num;
if (int.TryParse(CurrentToken.Text, out num))
{
expression = new NumericExpression(dim, num);
}
else
{
//parse error
}
}
}
else if (negativeSecond != null)
{
//xn-b
int num;
if (int.TryParse(negativeSecond, out num))
{
expression = new NumericExpression(dim, -num);
currentPosition--;
}
else
{
//parse error
}
}
else if (CurrentToken.Text == ")")
{
expression = new NumericExpression(dim, 0);
currentPosition--;
}
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.Number)
{
//b
int num;
if (int.TryParse(CurrentToken.Text, out num))
{
expression = new NumericExpression(0, num * (negative ? -1 : 1));
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.Ident)
{
//odd or even
if (CurrentToken.Text == "odd")
{
expression = new OddExpression();
}
else if (CurrentToken.Text == "even")
{
expression = new OddExpression();
}
else
{
//parse error
}
}
else if (CurrentToken.TokenType == SelectorTokenType.String)
{
string withoutQuotes = CurrentToken.Text.Substring(1, CurrentToken.Text.Length - 2);
if (CurrentToken.Text == "odd")
{
expression = new OddExpression();
}
else if (CurrentToken.Text == "even")
{
expression = new OddExpression();
}
else
{
//parse error
}
}
return(expression);
}