BuilderNode ParseTree(ITokenCollection tokens)
{
Func <IToken, bool> splitPredicate = token =>
{
var maxWeight = tokens.OfType <OperationToken>().Any()
? tokens.OfType <OperationToken>().Max(t => t.Weight)
: 0;
var operationToken = token as OperationToken;
if (operationToken != null && operationToken.Weight == maxWeight)
{
return(true);
}
return(false);
};
var split = tokens.Split(splitPredicate);
if (split.Delimiter == null)
{
var token = split.Left.First();
return(ParseNode(token));
}
var node = new BuilderNode
{
Token = split.Delimiter,
Left = ParseTree(split.Left),
Right = ParseTree(split.Right)
};
return(node);
}
public IEnumerable <IToken> Assemble(ITokenCollection tokens)
{
var digitTokens = tokens.OfType <DigitToken>().ToArray();
var numberStr = digitTokens.Aggregate("", (accumulator, token) => accumulator + token.Value);
var number = double.Parse(numberStr);
yield return(new NumberToken(number));
}
public ITokenCollection Tokenize(ITokenCollection tokens)
{
if (!tokens.OfType <ParenthesisToken>().Any())
{
return(tokens);
}
var result = new List <IToken>();
var parentheses = new List <IToken>();
var isParenthesisOpened = false;
var scopeDepth = 0;
foreach (var token in tokens)
{
if (isParenthesisOpened)
{
if (token.IsParenthesis(Parenthesis.Left))
{
scopeDepth++;
}
else if (token.IsParenthesis(Parenthesis.Right))
{
scopeDepth--;
if (scopeDepth == 0)
{
parentheses = Tokenize(parentheses.ToTokenCollection()).ToList();
var parenthesesToken = new ParenthesesToken(new TokenCollection(parentheses));
result.Add(parenthesesToken);
parentheses.Clear();
isParenthesisOpened = false;
continue;
}
}
parentheses.Add(token);
}
else
{
if (token.IsParenthesis(Parenthesis.Left))
{
isParenthesisOpened = true;
scopeDepth++;
}
else
{
result.Add(token);
}
}
}
return(result.ToTokenCollection());
}