/// <summary>
/// Checks to see if a string is a variable.
/// </summary>
/// <remarks><pre>
/// 2004-07-20 - Jeremy Roberts
/// 2004-08-11 - Jeremy Roberts
/// Changed to check to see if it is a number.
/// </pre></remarks>
/// <param name="token">String to check.</param>
/// <returns></returns>
public bool IsVariable(string token)
{
token = token.ToLower();
if (IsConstant(token))
{
return(false);
}
if (!ExpressionKeywords.IsOperand(token))
{
return(false);
}
if (IsNumber(token))
{
return(false);
}
if (IsString(token))
{
return(false);
}
return(true);
}
//private void CheckPostVectorForEvaluability(string inFix, string[] tokens)
private void CheckPostVectorForEvaluability(string[] tokens)
{
var workstack = new Stack <string>();
for (int index = 0; index < tokens.Length; index++)
{
string token = tokens[index];
if (ExpressionKeywords.IsOperator(token) ||
ExpressionKeywords.Functions.Contains(token) ||
ExpressionKeywords.ConditionalOperators.Contains(token))
{
var kw = ExpressionKeywords.Keywords.OfType <Procedure>()
.Where(x => x.Name == token)
.Select(x => x)
.Single();
if (kw.VariableOperandsCount)
{
var current = "";
while (current != "param_terminator")
{
current = workstack.Pop();
}
}
else
{
try {
for (int i = 0; i < kw.NumParameters; i++)
{
workstack.Pop();
}
}
catch {
throw new ExpressionException("Operator error! \"" + token + "\". ");
}
}
if (kw.AlwaysReturnsValue)
{
workstack.Push("0");
}
}
else
{
workstack.Push(token);
}
}
if (workstack.Count != 1)
{
throw new ExpressionException("Expression formatted incorrecty! ");
}
}
private void CheckGrouping(string inFix)
{
string errorMsg = "Grouping error! Open missing. " + " " + inFix;
var groupingStack = new Stack <char>();
foreach (var token in inFix.ToArray())
{
if (!ExpressionKeywords.GroupOperators.Contains(token.ToString()))
{
continue;
}
if (ExpressionKeywords.OpenGroupOperators.Contains(token.ToString()))
{
groupingStack.Push(token);
continue;
}
if (groupingStack.Count == 0)
{
throw new ExpressionException(errorMsg);
}
var last = groupingStack.Pop();
if (ExpressionKeywords.ClosingGroupOperators.Contains(token.ToString()))
{
Grouping g = ExpressionKeywords.GetGroupingFromClose(token.ToString());
if (last.ToString() != g.Open)
{
throw new ExpressionException(errorMsg);
}
}
}
if (groupingStack.Count != 0)
{
throw new ExpressionException("Grouping error! Close missing. " + " " + inFix);
}
}
/// <summary>
/// Convecs an infix string to a post fix string.
/// </summary>
/// <remarks><pre>
/// 2004-07-19 - Jeremy Roberts
/// </pre></remarks>
/// <param name="func">The function to convert</param>
/// <returns>A post fix string.</returns>
protected string Infix2Postfix(string func)
{
func = new InfixExpression(func).Expression;
string[] inFix = func.Split(new[] { ' ' });
var postFix = new Stack <string>();
var operators = new Stack <string>();
string currOperator;
foreach (string token in inFix)
{
if (ExpressionKeywords.IsOperand(token))
{
postFix.Push(token);
}
else if (ExpressionKeywords.OpenGroupOperators.Contains(token))
{
if (operators.Count > 0)
{
var kw = ExpressionKeywords.Keywords.OfType <Procedure>()
.Where(x => x.Name == operators.Peek())
.Select(x => x)
.SingleOrDefault();
if (kw != null &&
kw.VariableOperandsCount)
{
postFix.Push("param_terminator");
}
}
operators.Push(token);
}
else if (ExpressionKeywords.ClosingGroupOperators.Contains(token))
{
Grouping g = ExpressionKeywords.GetGroupingFromClose(token);
currOperator = operators.Pop();
while (currOperator != g.Open)
{
postFix.Push(currOperator);
currOperator = operators.Pop();
}
if (operators.Count > 0 &&
ExpressionKeywords.Functions.Contains(operators.Peek()))
{
postFix.Push(operators.Pop());
}
}
else if (ExpressionKeywords.IsOperator(token))
{
// while precedence of the operator is <= precedence of the token
while (operators.Count > 0)
{
if (ExpressionKeywords.GetPrecedence(token)
<= ExpressionKeywords.GetPrecedence(operators.Peek()))
{
currOperator = operators.Pop();
postFix.Push(currOperator);
}
else
{
break;
}
}
operators.Push(token);
}
}
while (operators.Count > 0)
{
currOperator = operators.Pop();
postFix.Push(currOperator);
}
// Build the post fix string.
string psString = string.Empty;
foreach (string item in postFix)
{
psString = item + " " + psString;
}
psString = psString.Trim();
return(psString);
}
/// <summary>
/// Convecs an infix string to a post fix string.
/// </summary>
/// <remarks><pre>
/// 2004-07-19 - Jeremy Roberts
/// </pre></remarks>
/// <param name="func">The function to convert</param>
/// <returns>A post fix string.</returns>
protected string Infix2Postfix(string func)
{
func = new InfixExpression(func).Expression;
string[] inFix = func.Split(new[] { ' ' });
var postFix = new Stack <string>();
var operators = new Stack <string>();
string currOperator;
foreach (string token in inFix)
{
if (ExpressionKeywords.IsOperand(token))
{
postFix.Push(token);
}
else if (ExpressionKeywords.OpenGroupOperators.Contains(token))
{
operators.Push(token);
}
else if (ExpressionKeywords.ClosingGroupOperators.Contains(token))
{
Grouping g = ExpressionKeywords.GetGroupingFromClose(token);
currOperator = operators.Pop();
while (currOperator != g.Open)
{
postFix.Push(currOperator);
currOperator = operators.Pop();
}
}
else if (ExpressionKeywords.IsOperator(token))
{
// while precedence of the operator is <= precedence of the token
while (operators.Count > 0)
{
if (ExpressionKeywords.GetPrecedence(token) <= ExpressionKeywords.GetPrecedence(operators.Peek()))
{
currOperator = operators.Pop();
postFix.Push(currOperator);
}
else
{
break;
}
}
operators.Push(token);
}
}
while (operators.Count > 0)
{
currOperator = operators.Pop();
postFix.Push(currOperator);
}
// Build the post fix string.
string psString = string.Empty;
foreach (string item in postFix)
{
psString = item + " " + psString;
}
psString = psString.Trim();
return(psString);
}
