public ParsedExpression Parse(string expression)
{
IList<IExpressionElement> tokens = Tokenize(expression);
if (tokens.Count == 0)
{
throw new ArgumentException("Empty expression.");
}
List<IExpressionElement> output = new List<IExpressionElement>();
Stack<IExpressionElement> stack = new Stack<IExpressionElement>();
Stack<int> argumentsStack = new Stack<int>();
Stack<bool> insideFunctionStack = new Stack<bool>();
bool afterFunction = false;
bool afterFnParenthesis = false;
bool afterNonFnParenthesis = false;
bool afterClosingParenthesis = false;
bool afterSeparator = false;
bool insideFunction = false;
int arguments = 0;
bool mustBeUnary = true;
int tokenIndex = -1;
foreach (IExpressionElement token in tokens)
{
tokenIndex++;
IExpressionElement nextToken = tokenIndex + 1 < tokens.Count ? tokens[tokenIndex + 1] : null;
// If the token is a number, then add it to the output queue.
if (!afterFunction && !afterClosingParenthesis && (token is ILiteral || token is IConstant || token is IVariable))
{
output.Add(token);
mustBeUnary = false;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = afterSeparator = false;
}
// If the token is a function token, then push it onto the stack.
else if (!afterFunction && !afterClosingParenthesis && (token is IFunction || (token is MultipleElements && (token as MultipleElements).Elements[0] is IFunction)))
{
stack.Push(token);
afterFunction = true;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = afterSeparator = false;
}
// If the token is a function argument separator (e.g., a comma):
// • Until the topmost element of the stack is a left parenthesis, pop the element onto the output queue.
// If no left parentheses are encountered, either the separator was misplaced or parentheses were mismatched.
else if (!afterFunction && insideFunction && token == Symbol.FunctionArgumentSeparator)
{
if (afterFnParenthesis)
{
throw new ArgumentException("Missing argument.");
}
while (stack.Peek() != Symbol.LeftParenthesis)
{
output.Add(stack.Pop());
}
if (stack.Peek() != Symbol.LeftParenthesis)
{
throw new ArgumentException("Either the separator is misplaced or parentheses are mismatched.");
}
arguments++;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = false;
afterSeparator = true;
}
// If the token is an operator, o1, then:
// • while there is an operator, o2, at the top of the stack, and either
// o1 is associative or left-associative and its precedence is less than (lower precedence) or equal to that of o2, or
// o1 is right-associative and its precedence is less than (lower precedence) that of o2,
// pop o2 off the stack, onto the output queue;
// • push o1 onto the stack.
else if (!afterFunction && (token is IOperator || (token is MultipleElements && (token as MultipleElements).Elements[0] is IOperator)))
{
IOperator op = null;
if ((mustBeUnary && token is IUnaryOperator) || (!mustBeUnary && token is IBinaryOperator))
{
op = token as IOperator;
}
else if (token is MultipleElements)
{
foreach (IExpressionElement elem in (token as MultipleElements).Elements)
{
if ((mustBeUnary && elem is IUnaryOperator) || (!mustBeUnary && elem is IBinaryOperator))
{
op = elem as IOperator;
break;
}
}
}
if (op == null)
{
throw new ArgumentException(string.Format("{0} is not {1} operator.", token.Name, mustBeUnary ? "an unary" : "a binary"));
}
IOperator sop = stack.Count > 0 ? stack.Peek() as IOperator : null;
while (sop != null && (
(
op is IBinaryOperator &&
(op as IBinaryOperator).Associativity != OperatorAssociativity.RightAssociative &&
op.Precedence <= sop.Precedence
)
||
(
(
(op is IBinaryOperator && (op as IBinaryOperator).Associativity == OperatorAssociativity.RightAssociative) ||
op is IUnaryOperator
)
&&
op.Precedence < sop.Precedence
)))
{
output.Add(stack.Pop());
sop = stack.Count > 0 ? stack.Peek() as IOperator : null;
}
stack.Push(op);
mustBeUnary = true;
afterClosingParenthesis = afterFnParenthesis = afterNonFnParenthesis = afterSeparator = false;
}
// If the token is a left parenthesis, then push it onto the stack.
else if (!afterClosingParenthesis && token == Symbol.LeftParenthesis)
{
stack.Push(token);
argumentsStack.Push(arguments);
insideFunctionStack.Push(insideFunction);
// initial argument count
arguments = nextToken == Symbol.RightParenthesis ? 0 : 1;
if (afterFunction)
{
afterNonFnParenthesis = afterFunction = false;
insideFunction = afterFnParenthesis = true;
}
else
{
afterNonFnParenthesis = true;
insideFunction = afterFnParenthesis = false;
}
mustBeUnary = true;
afterClosingParenthesis = afterSeparator = false;
}
// If the token is a right parenthesis:
// • Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue.
// • Pop the left parenthesis from the stack, but not onto the output queue.
// • If the token at the top of the stack is a function token, pop it and onto the output queue.
// • If the stack runs out without finding a left parenthesis, then there are mismatched parentheses.
else if (!afterFunction && !afterSeparator && token == Symbol.RightParenthesis)
{
if (afterNonFnParenthesis)
{
throw new ArgumentException("Unexpected token: '()'.");
}
if (stack.Count == 0)
{
throw new ArgumentException("There are mismatched parentheses.");
}
while (stack.Peek() != Symbol.LeftParenthesis)
{
output.Add(stack.Pop());
if (stack.Count == 0)
{
throw new ArgumentException("There are mismatched parentheses.");
}
}
IExpressionElement parenthesis = stack.Pop(); // parenthesis
if (stack.Count > 0)
{
IExpressionElement elem = stack.Peek();
if (elem is IFunction || (elem is MultipleElements && (elem as MultipleElements).Elements[0] is IFunction))
{
elem = stack.Pop();
IExpressionElement func = null;
if (elem is IFunction)
{
if ((elem as IFunction).ParametersCount != arguments)
{
UndefinedFunctionFoundEventArgs args = new UndefinedFunctionFoundEventArgs(elem.Name, arguments);
if (UndefinedFunctionFound != null)
{
UndefinedFunctionFound(this, args);
}
if (!args.Handled)
{
throw new ArgumentException(string.Format("There is no function ‘{0}’ with {1} parameters defined.", elem.Name, arguments));
}
elem = new UnknownFunction(elem.Name);
(elem as UnknownFunction).ParametersCount = arguments;
}
func = elem;
}
else
{
foreach (IFunction f in (elem as MultipleElements).Elements)
{
if (f.ParametersCount == arguments)
{
func = f;
break;
}
}
if (func == null)
{
UndefinedFunctionFoundEventArgs args = new UndefinedFunctionFoundEventArgs((elem as MultipleElements).Elements[0].Name, arguments);
if (UndefinedFunctionFound != null)
{
UndefinedFunctionFound(this, args);
}
if (!args.Handled)
{
throw new ArgumentException(string.Format("There is no function ‘{0}’ with {1} parameters defined.", args.Name, arguments));
}
func = new UnknownFunction(args.Name);
(func as UnknownFunction).ParametersCount = arguments;
}
}
output.Add(func);
}
}
arguments = argumentsStack.Count > 0 ? argumentsStack.Pop() : 0;
insideFunction = insideFunctionStack.Pop();
afterFnParenthesis = afterNonFnParenthesis = mustBeUnary = afterSeparator = false;
afterClosingParenthesis = true;
}
else
{
IExpressionElement elem = token;
if (token is MultipleElements)
{
elem = (token as MultipleElements).Elements[0];
}
throw new ArgumentException(string.Format("Unexpected token: ‘{0}’", elem.Name));
}
}
// When there are no more tokens to read:
// • While there are still operator tokens in the stack:
// • If the operator token on the top of the stack is a parenthesis, then there are mismatched parentheses.
// • Pop the operator onto the output queue.
while (stack.Count > 0)
{
if (stack.Peek() == Symbol.LeftParenthesis || stack.Peek() == Symbol.RightParenthesis)
{
var r = stack.Peek();
throw new ArgumentException("There are mismatched parentheses.");
}
output.Add(stack.Pop());
}
return new ParsedExpression(output, ZeroOnError);
}
private IList<IExpressionElement> Tokenize(string expression)
{
Dictionary<string, List<IExpressionElement>> dict = new Dictionary<string, List<IExpressionElement>>();
foreach (IExpressionElement element in Constants.Cast<IExpressionElement>().
Concat(Variables.Cast<IExpressionElement>()).
Concat(Operators.Cast<IExpressionElement>()).
Concat(Functions.Cast<IExpressionElement>()).
Concat(Statements.Cast<IExpressionElement>()))
{
string name = element.Name;
if (!dict.ContainsKey(name))
{
dict[name] = new List<IExpressionElement>();
}
if (dict[name].Count > 0)
{
if (!(element is IOperator || element is IFunction))
{
throw new ArgumentException("Only operators and functions can be overloaded.");
}
IExpressionElement elem = dict[name][0];
if ((elem is IOperator && element is IFunction) ||
(elem is IFunction && element is IOperator))
{
throw new ArgumentException("Function and operator cannot have the same name.");
}
if (element is IOperator)
{
foreach (IExpressionElement eelem in dict[name])
{
if ((element is IUnaryOperator && eelem is IUnaryOperator) ||
(element is IBinaryOperator && eelem is IBinaryOperator))
{
throw new ArgumentException("There cannot be two identical operators.");
}
}
}
if (element is IFunction)
{
IFunction felement = element as IFunction;
foreach (IExpressionElement eelem in dict[name])
{
IFunction felem = eelem as IFunction;
if (felem != null && felem.Name == felement.Name && felem.ParametersCount == felement.ParametersCount)
{
throw new ArgumentException("There cannot be two identical functions.");
}
}
}
}
dict[name].Add(element);
}
List<IExpressionElement> tokens = new List<IExpressionElement>();
int i = 0;
int l = expression.Length;
while (i < l)
{
char c = expression[i];
if (char.IsWhiteSpace(c)) { /* eat */ }
else if (NumberChars.IndexOf(c) >= 0)
{
int pos = i;
StringBuilder token = new StringBuilder();
while (i < l && NumberChars.IndexOf(expression[i]) >= 0)
{
token.Append(expression[i]);
i++;
}
i--;
decimal value = 0;
string strtoken = token.ToString();
if (decimal.TryParse(strtoken, NumberStyles.Float, CultureInfo.InvariantCulture, out value))
{
tokens.Add(new Literal(value));
}
else
{
throw new ArgumentException(string.Format(ParseExceptionText, "number", pos, strtoken));
}
}
else if (c == '(')
{
tokens.Add(Symbol.LeftParenthesis);
}
else if (c == ')')
{
tokens.Add(Symbol.RightParenthesis);
}
else if (c == ',')
{
tokens.Add(Symbol.FunctionArgumentSeparator);
}
else if (char.IsLetter(c) || AdditionalVariableChars.IndexOf(c) >= 0)
{
StringBuilder token = new StringBuilder();
while (i < l && (char.IsLetterOrDigit(expression[i]) || AdditionalVariableChars.IndexOf(expression[i]) >= 0))
{
token.Append(expression[i]);
i++;
}
i--;
string strtoken = token.ToString();
if (dict.ContainsKey(strtoken))
{
List<IExpressionElement> elements = dict[strtoken];
IExpressionElement element;
if (elements.Count == 1)
{
element = elements[0];
}
else
{
element = new MultipleElements(elements);
}
tokens.Add(element);
}
else
{
int nx = i + 1;
while (nx < l && char.IsWhiteSpace(expression[nx]))
{
nx++;
}
IExpressionElement element = null;
if (nx < l && expression[nx] == '(')
{
element = new UnknownFunction(strtoken);
}
else
{
UndefinedVariableFoundEventArgs args = new UndefinedVariableFoundEventArgs(strtoken);
if (UndefinedVariableFound != null)
{
UndefinedVariableFound(this, args);
}
if (!args.Handled)
{
throw new ArgumentException(string.Format("There is no variable ‘{0}’ defined.", args.Name));
}
element = args.HandledVariable ?? new UnknownVariable(strtoken);
Variables.Add((IVariable)element);
if (!dict.ContainsKey(element.Name))
{
dict[element.Name] = new List<IExpressionElement>();
}
if (dict[element.Name].Count > 0 && !(element is IOperator || element is IFunction))
{
throw new ArgumentException("Only operators and functions can be overloaded.");
}
dict[element.Name].Add(element);
}
tokens.Add(element);
}
}
else if (char.IsSymbol(c) || char.IsPunctuation(c))
{
int j = i;
StringBuilder token = new StringBuilder();
while (i < l && (char.IsSymbol(expression[i]) || char.IsPunctuation(expression[i])))
{
token.Append(expression[i]);
i++;
}
i--;
string strop = token.ToString();
while (!dict.ContainsKey(strop))
{
strop = strop.Substring(0, strop.Length - 1);
i--;
if (strop.Length == 0)
{
throw new ArgumentException(string.Format(ParseExceptionText, "operator", j, expression[j]));
}
}
if (dict.ContainsKey(strop))
{
List<IExpressionElement> ops = dict[strop];
IExpressionElement op;
if (ops.Count == 1)
{
op = ops[0];
}
else
{
op = new MultipleElements(ops);
}
tokens.Add(op);
}
else
{
throw new ArgumentException(string.Format(ParseExceptionText, "operator", j, strop));
}
}
else
{
throw new ArgumentException(string.Format(ParseExceptionText, "character", i, c));
}
i++;
}
return tokens.AsReadOnly();
}
public ParsedExpression Parse(string expression)
{
IList <IExpressionElement> tokens = Tokenize(expression);
if (tokens.Count == 0)
{
throw new ArgumentException("Empty expression.");
}
List <IExpressionElement> output = new List <IExpressionElement>();
Stack <IExpressionElement> stack = new Stack <IExpressionElement>();
Stack <int> argumentsStack = new Stack <int>();
Stack <bool> insideFunctionStack = new Stack <bool>();
bool afterFunction = false;
bool afterFnParenthesis = false;
bool afterNonFnParenthesis = false;
bool afterClosingParenthesis = false;
bool afterSeparator = false;
bool insideFunction = false;
int arguments = 0;
bool mustBeUnary = true;
int tokenIndex = -1;
foreach (IExpressionElement token in tokens)
{
tokenIndex++;
IExpressionElement nextToken = tokenIndex + 1 < tokens.Count ? tokens[tokenIndex + 1] : null;
// If the token is a number, then add it to the output queue.
if (!afterFunction && !afterClosingParenthesis && (token is ILiteral || token is IConstant || token is IVariable))
{
output.Add(token);
mustBeUnary = false;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = afterSeparator = false;
}
// If the token is a function token, then push it onto the stack.
else if (!afterFunction && !afterClosingParenthesis && (token is IFunction || (token is MultipleElements && (token as MultipleElements).Elements[0] is IFunction)))
{
stack.Push(token);
afterFunction = true;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = afterSeparator = false;
}
// If the token is a function argument separator (e.g., a comma):
// • Until the topmost element of the stack is a left parenthesis, pop the element onto the output queue.
// If no left parentheses are encountered, either the separator was misplaced or parentheses were mismatched.
else if (!afterFunction && insideFunction && token == Symbol.FunctionArgumentSeparator)
{
if (afterFnParenthesis)
{
throw new ArgumentException("Missing argument.");
}
while (stack.Peek() != Symbol.LeftParenthesis)
{
output.Add(stack.Pop());
}
if (stack.Peek() != Symbol.LeftParenthesis)
{
throw new ArgumentException("Either the separator is misplaced or parentheses are mismatched.");
}
arguments++;
afterClosingParenthesis = afterNonFnParenthesis = afterFnParenthesis = false;
afterSeparator = true;
}
// If the token is an operator, o1, then:
// • while there is an operator, o2, at the top of the stack, and either
// o1 is associative or left-associative and its precedence is less than (lower precedence) or equal to that of o2, or
// o1 is right-associative and its precedence is less than (lower precedence) that of o2,
// pop o2 off the stack, onto the output queue;
// • push o1 onto the stack.
else if (!afterFunction && (token is IOperator || (token is MultipleElements && (token as MultipleElements).Elements[0] is IOperator)))
{
IOperator op = null;
if ((mustBeUnary && token is IUnaryOperator) || (!mustBeUnary && token is IBinaryOperator))
{
op = token as IOperator;
}
else if (token is MultipleElements)
{
foreach (IExpressionElement elem in (token as MultipleElements).Elements)
{
if ((mustBeUnary && elem is IUnaryOperator) || (!mustBeUnary && elem is IBinaryOperator))
{
op = elem as IOperator;
break;
}
}
}
if (op == null)
{
throw new ArgumentException(string.Format("{0} is not {1} operator.", token.Name, mustBeUnary ? "an unary" : "a binary"));
}
IOperator sop = stack.Count > 0 ? stack.Peek() as IOperator : null;
while (sop != null && (
(
op is IBinaryOperator &&
(op as IBinaryOperator).Associativity != OperatorAssociativity.RightAssociative &&
op.Precedence <= sop.Precedence
)
||
(
(
(op is IBinaryOperator && (op as IBinaryOperator).Associativity == OperatorAssociativity.RightAssociative) ||
op is IUnaryOperator
)
&&
op.Precedence < sop.Precedence
)))
{
output.Add(stack.Pop());
sop = stack.Count > 0 ? stack.Peek() as IOperator : null;
}
stack.Push(op);
mustBeUnary = true;
afterClosingParenthesis = afterFnParenthesis = afterNonFnParenthesis = afterSeparator = false;
}
// If the token is a left parenthesis, then push it onto the stack.
else if (!afterClosingParenthesis && token == Symbol.LeftParenthesis)
{
stack.Push(token);
argumentsStack.Push(arguments);
insideFunctionStack.Push(insideFunction);
// initial argument count
arguments = nextToken == Symbol.RightParenthesis ? 0 : 1;
if (afterFunction)
{
afterNonFnParenthesis = afterFunction = false;
insideFunction = afterFnParenthesis = true;
}
else
{
afterNonFnParenthesis = true;
insideFunction = afterFnParenthesis = false;
}
mustBeUnary = true;
afterClosingParenthesis = afterSeparator = false;
}
// If the token is a right parenthesis:
// • Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue.
// • Pop the left parenthesis from the stack, but not onto the output queue.
// • If the token at the top of the stack is a function token, pop it and onto the output queue.
// • If the stack runs out without finding a left parenthesis, then there are mismatched parentheses.
else if (!afterFunction && !afterSeparator && token == Symbol.RightParenthesis)
{
if (afterNonFnParenthesis)
{
throw new ArgumentException("Unexpected token: '()'.");
}
if (stack.Count == 0)
{
throw new ArgumentException("There are mismatched parentheses.");
}
while (stack.Peek() != Symbol.LeftParenthesis)
{
output.Add(stack.Pop());
if (stack.Count == 0)
{
throw new ArgumentException("There are mismatched parentheses.");
}
}
IExpressionElement parenthesis = stack.Pop(); // parenthesis
if (stack.Count > 0)
{
IExpressionElement elem = stack.Peek();
if (elem is IFunction || (elem is MultipleElements && (elem as MultipleElements).Elements[0] is IFunction))
{
elem = stack.Pop();
IExpressionElement func = null;
if (elem is IFunction)
{
if ((elem as IFunction).ParametersCount != arguments)
{
UndefinedFunctionFoundEventArgs args = new UndefinedFunctionFoundEventArgs(elem.Name, arguments);
if (UndefinedFunctionFound != null)
{
UndefinedFunctionFound(this, args);
}
if (!args.Handled)
{
throw new ArgumentException(string.Format("There is no function ‘{0}’ with {1} parameters defined.", elem.Name, arguments));
}
elem = new UnknownFunction(elem.Name);
(elem as UnknownFunction).ParametersCount = arguments;
}
func = elem;
}
else
{
foreach (IFunction f in (elem as MultipleElements).Elements)
{
if (f.ParametersCount == arguments)
{
func = f;
break;
}
}
if (func == null)
{
UndefinedFunctionFoundEventArgs args = new UndefinedFunctionFoundEventArgs((elem as MultipleElements).Elements[0].Name, arguments);
if (UndefinedFunctionFound != null)
{
UndefinedFunctionFound(this, args);
}
if (!args.Handled)
{
throw new ArgumentException(string.Format("There is no function ‘{0}’ with {1} parameters defined.", args.Name, arguments));
}
func = new UnknownFunction(args.Name);
(func as UnknownFunction).ParametersCount = arguments;
}
}
output.Add(func);
}
}
arguments = argumentsStack.Count > 0 ? argumentsStack.Pop() : 0;
insideFunction = insideFunctionStack.Pop();
afterFnParenthesis = afterNonFnParenthesis = mustBeUnary = afterSeparator = false;
afterClosingParenthesis = true;
}
else
{
IExpressionElement elem = token;
if (token is MultipleElements)
{
elem = (token as MultipleElements).Elements[0];
}
throw new ArgumentException(string.Format("Unexpected token: ‘{0}’", elem.Name));
}
}
// When there are no more tokens to read:
// • While there are still operator tokens in the stack:
// • If the operator token on the top of the stack is a parenthesis, then there are mismatched parentheses.
// • Pop the operator onto the output queue.
while (stack.Count > 0)
{
if (stack.Peek() == Symbol.LeftParenthesis || stack.Peek() == Symbol.RightParenthesis)
{
var r = stack.Peek();
throw new ArgumentException("There are mismatched parentheses.");
}
output.Add(stack.Pop());
}
return(new ParsedExpression(output, ZeroOnError));
}
