/// <summary>
/// Takes a string and evaluates it as a mathematical expression, replacing any variables "ie, [X]" with the provided values
/// </summary>
/// <param name="identifier">An identifier for the string</param>
/// <param name="input">The string to evaluate</param>
/// <param name="variables">The Dictionary containing the variables and their values</param>
/// <returns>The result of the evaluation</returns>
public static double ParseMath(string identifier, string input, Dictionary <string, string> variables)
{
double currentVal = 0;
string stack = "";
try
{
if (identifier != null) //recursive calls will pass null to avoid firing the events
{
input = ReplaceMathVariables(identifier, input, variables);
}
string lastOp = "+";
string[] ops = { "+", "-", "*", "/", "%", "^", "(", "e", "E" };
string[] functions = { "min", "max", "l", "ln", "L", "log", "abs", "sign", "if" }; //if (a < b ? stuff : other stuff)
for (int i = 0; i < input.Length; ++i)
{
string ch = input[i].ToString();
bool isOp = false, isFunction = false;
foreach (string op in ops)
{
if (op == ch)
{
isOp = true;
break;
}
}
if (!isOp)
{
foreach (string fun in functions)
{
if (fun[0] == input[i])
{
isFunction = true;
break;
}
}
}
if (isOp)
{
if (ch == "-" && (stack.Trim() == ""))
{
stack += ch;
}
else if (ch == "e" || ch == "E")
{
int index;
for (index = i + 2; index < input.Length; ++index)
{
string ch2 = input[index].ToString();
if (ops.Contains(ch2))
{
break;
}
}
string sub = input.Substring(i + 1, index - i - 1);
double exp = ParseMath(null, sub, null);
double newVal = double.Parse(stack) * Math.Pow(10, exp);
currentVal = DoMath(currentVal, lastOp, newVal.ToString());
stack = "0";
lastOp = "+";
i = index - 1;
}
else if (ch == "(")
{
int j = FindEndParenthesis(input, i)[0];
string sub = input.Substring(i + 1, j - i - 1);
string val = ParseMath(null, sub, null).ToString();
input = input.Substring(0, i) + val + input.Substring(j + 1);
--i;
}
else
{
currentVal = DoMath(currentVal, lastOp, stack);
lastOp = ch;
stack = "";
}
}
else if (isFunction)
{
int subStart = input.IndexOf('(', i) + 1;
string function = input.Substring(i, subStart - i - 1);
int[] parenComma = FindEndParenthesis(input, subStart - 1);
int j = parenComma[0];
int comma = parenComma[1];
string sub = input.Substring(subStart, j - subStart);
double val = 0.0;
if (function == "if")
{
val = DoIfStatement(sub);
}
else if (function == "l" || function == "ln")
{
val = ParseMath(null, sub, null);
val = Math.Log(val);
}
else if (function == "L" || function == "log")
{
val = ParseMath(null, sub, null);
val = Math.Log10(val);
}
else if (function == "max" || function == "min")
{
string[] parts = new string[2];
parts[0] = input.Substring(subStart, comma - subStart);
parts[1] = input.Substring(comma + 1, j - comma - 1);
double sub1 = ParseMath(null, parts[0], null);
double sub2 = ParseMath(null, parts[1], null);
if (function == "max")
{
val = Math.Max(sub1, sub2);
}
else if (function == "min")
{
val = Math.Min(sub1, sub2);
}
}
else if (function == "sign")
{
val = ParseMath(null, sub, null);
if (val >= 0)
{
val = 1;
}
else
{
val = -1;
}
}
else if (function == "abs")
{
val = ParseMath(null, sub, null);
val = Math.Abs(val);
}
input = input.Substring(0, i) + val.ToString() + input.Substring(j + 1);
i--;
}
else
{
stack += ch;
}
}
currentVal = DoMath(currentVal, lastOp, stack);
}
catch (Exception ex)
{
MagiCore.LogException(ex, string.Format("Exception encountered while parsing '{0}' : '{1}'. Current value: '{2}' Stack: {3}", identifier, input, currentVal, stack));
currentVal = 0;
}
return(currentVal);
}
/// <summary>
/// Performs parsing of inline if statements
/// </summary>
/// <param name="statement">The statement string to act on</param>
/// <returns>The result of the if statement</returns>
private static double DoIfStatement(string statement)
{
//At this point "statement" would look something like a < b ? stuff : other stuff
//We need to grab the conditional and the two possible values, then do the conditional and evaluate the correct value
string[] mathConditionals = { "<", ">", "<=", ">=", "==", "!=" }; //do we want to support && and ||, too? Ideally yes, but it's way tougher
string[] stringConditionals = { " seq ", " sneq " };
string[] conditionals = mathConditionals.Concat(stringConditionals).ToArray();
double val = 0.0;
try
{
// Debug.Log("MagiCore: Statement = " + statement);
int indexOfQMark = statement.IndexOf("?");
string conditionalSection = statement.Substring(0, indexOfQMark);
//string[] condSides = conditionalSection.Split(conditionals, StringSplitOptions.RemoveEmptyEntries);
foreach (string conditional in conditionals)
{
conditionalSection = conditionalSection.Replace(conditional, ";" + conditional + ";");
}
string[] parts = conditionalSection.Split(';');
//this is a kind of horrible method that I got from here, but avoided excessive regex: http://stackoverflow.com/a/2484982
//lets assume there are only three elements
if (parts.Length < 3)
{
return(0.0);
}
//check that we aren't doing string comparisons, if so then we don't parse math on val1 or val2
string condition = parts[1].Trim();
double val1 = 0;
double val2 = 0;
string val1S = parts[0].Trim();
string val2S = parts[1].Trim();
if (mathConditionals.Contains(condition))
{
//do math on part one
//do math on part two
//compare them
val1 = ParseMath(null, parts[0], null);
val2 = ParseMath(null, parts[2], null);
}
// Debug.Log("MagiCore: val1 = " + val1);
// Debug.Log("MagiCore: val2 = " + val2);
int indexOfColon = indexOfQMark;
int depth = 0;
for (int i = indexOfQMark + 1; i < statement.Length; i++)
{
char s = statement[i];
if (s == '(')
{
depth++;
}
if (s == ')')
{
depth--;
}
if (s == ':' && depth == 0)
{
indexOfColon = i;
}
if (depth < 0)
{
break;
}
}
string leftOption = statement.Substring(indexOfQMark + 1, indexOfColon - indexOfQMark - 1); //starts at "?" and ends at last ":" for this depth
string rightOption = statement.Substring(indexOfColon + 1); //starts at last ":" and ends at end of statment
// Debug.Log("MagiCore: left option = " + leftOption);
// Debug.Log("MagiCore: right option = " + rightOption);
string selectedOption = "";
switch (condition)
{
case "<": selectedOption = val1 < val2 ? leftOption : rightOption; break;
case ">": selectedOption = val1 > val2 ? leftOption : rightOption; break;
case "<=": selectedOption = val1 <= val2 ? leftOption : rightOption; break;
case ">=": selectedOption = val1 >= val2 ? leftOption : rightOption; break;
case "==": selectedOption = val1 == val2 ? leftOption : rightOption; break;
case "!=": selectedOption = val1 != val2 ? leftOption : rightOption; break;
case "seq": selectedOption = string.Equals(val1S, val2S, StringComparison.Ordinal) ? leftOption : rightOption; break;
case "sneq": selectedOption = !string.Equals(val1S, val2S, StringComparison.Ordinal) ? leftOption : rightOption; break;
default: selectedOption = leftOption; break;
}
val = ParseMath(null, selectedOption, null);
}
catch (Exception ex)
{
MagiCore.LogException(ex, string.Format("Exception while performing if statement. Statement: '{1}'", statement));
val = 0;
}
return(val);
}
