private string doEvaluate(Node node, IdentifierLookup lookup)
{
if ((node.Operator == tkIF.ToString()) && (node.Condition != null))
{
var cond = doEvaluate(node.Condition, lookup);
if (string.Equals(cond,"1") ||
string.Equals(cond, "true", StringComparison.InvariantCultureIgnoreCase) ||
string.Equals(cond, "yes", StringComparison.InvariantCultureIgnoreCase))
return (node.Left == null) ? "" : doEvaluate(node.Left, lookup);
else
return (node.Right == null) ? "" : doEvaluate(node.Right, lookup);
}//if tkIF
string lnd = (node.Left == null) ? "" : doEvaluate(node.Left, lookup);
string rnd = (node.Right == null) ? "" : doEvaluate(node.Right, lookup);
//resolve identifier
if ((lnd == "") && (rnd == ""))
{
string rslt = node.Operator;
if (lookup!=null) rslt = lookup(rslt);
else
if (OnIdentifierLookup != null) rslt = OnIdentifierLookup(rslt);
return rslt;
}//if
double left;
double right;
try
{
left = getVal(lnd);
right = getVal(rnd);
}
catch
{
if ((node.Operator == tkMINUS) && (lnd == ""))//test for unary -
{
try
{
right = getVal(rnd);//may fail again
return (-right).ToString();
}
catch
{
}
}//if
if ((node.Operator == tkPLUS) && (lnd != null) && (rnd != null))
return (((string)lnd) + ((string)rnd));
else
throw;
}
switch (node.Operator)
{
case tkPLUS:
{
return (left + right).ToString();
}
case tkMINUS:
{
return (left - right).ToString();
}
case tkMUL:
{
return (left * right).ToString();
}
case tkDIV:
{
return (left / right).ToString();
}
case tkMOD:
{
return (left % right).ToString();
}
case tkEQ:
{
return ((left == right) ? "1" : "0");
}
case tkLE:
{
return ((left <= right) ? "1" : "0");
}
case tkGE:
{
return ((left >= right) ? "1" : "0");
}
case tkL:
{
return ((left < right) ? "1" : "0");
}
case tkG:
{
return ((left > right) ? "1" : "0");
}
case tkNE:
{
return ((left != right) ? "1" : "0");
}
case tkAND:
{
return (((left != 0) && (right != 0)) ? "1" : "0");
}
case tkOR:
{
return (((left != 0) || (right != 0)) ? "1" : "0");
}
case tkXOR:
{
return (((left != 0) ^ (right != 0)) ? "1" : "0");
}
case tkNOT:
{
return ((!(right != 0)) ? "1" : "0");
}
default:
{
/* call delegate here*/
break;
}//default
}//switch
return null;
}
}//getVal
private string doEvaluate(Node node, IdentifierLookup lookup)
{
if ((node.Operator == tkIF.ToString()) && (node.Condition != null))
{
var cond = doEvaluate(node.Condition, lookup);
if (string.Equals(cond, "1") ||
string.Equals(cond, "true", StringComparison.InvariantCultureIgnoreCase) ||
string.Equals(cond, "yes", StringComparison.InvariantCultureIgnoreCase))
{
return((node.Left == null) ? "" : doEvaluate(node.Left, lookup));
}
else
{
return((node.Right == null) ? "" : doEvaluate(node.Right, lookup));
}
}//if tkIF
string lnd = (node.Left == null) ? "" : doEvaluate(node.Left, lookup);
string rnd = (node.Right == null) ? "" : doEvaluate(node.Right, lookup);
//resolve identifier
if ((lnd == "") && (rnd == ""))
{
string rslt = node.Operator;
if (lookup != null)
{
rslt = lookup(rslt);
}
else
if (OnIdentifierLookup != null)
{
rslt = OnIdentifierLookup(rslt);
}
return(rslt);
}//if
double left;
double right;
try
{
left = getVal(lnd);
right = getVal(rnd);
}
catch
{
if ((node.Operator == tkMINUS) && (lnd == ""))//test for unary -
{
try
{
right = getVal(rnd);//may fail again
return((-right).ToString());
}
catch
{
}
}//if
if ((node.Operator == tkPLUS) && (lnd != null) && (rnd != null))
{
return(((string)lnd) + ((string)rnd));
}
else
{
throw;
}
}
switch (node.Operator)
{
case tkPLUS:
{
return((left + right).ToString());
}
case tkMINUS:
{
return((left - right).ToString());
}
case tkMUL:
{
return((left * right).ToString());
}
case tkDIV:
{
return((left / right).ToString());
}
case tkMOD:
{
return((left % right).ToString());
}
case tkEQ:
{
return((left == right) ? "1" : "0");
}
case tkLE:
{
return((left <= right) ? "1" : "0");
}
case tkGE:
{
return((left >= right) ? "1" : "0");
}
case tkL:
{
return((left < right) ? "1" : "0");
}
case tkG:
{
return((left > right) ? "1" : "0");
}
case tkNE:
{
return((left != right) ? "1" : "0");
}
case tkAND:
{
return(((left != 0) && (right != 0)) ? "1" : "0");
}
case tkOR:
{
return(((left != 0) || (right != 0)) ? "1" : "0");
}
case tkXOR:
{
return(((left != 0) ^ (right != 0)) ? "1" : "0");
}
case tkNOT:
{
return((!(right != 0)) ? "1" : "0");
}
default:
{
/* call delegate here*/
break;
} //default
} //switch
return(null);
}//Evaluator doEvaluate
/// <summary>
/// Evaluate expression and return result - either string or numerical value
/// </summary>
public string Evaluate(IdentifierLookup lookup = null)
{
return doEvaluate(m_Root, lookup);
}
/// <summary>
/// Evaluate expression and return result - either string or numerical value
/// </summary>
public string Evaluate(IdentifierLookup lookup = null)
{
return(doEvaluate(m_Root, lookup));
}//Evaluator.evaluate
