/// <summary>
/// Pre-calculates the extra operators (defined at the <see cref="Custom.LeftAssociativeOperators"/> and <see cref="Custom.RightAssociativeOperators"/> for a given math expression.
/// </summary>
/// <param name="expression">The math expression to translate.</param>
/// <param name="rightAssociative">Determines the operator associativity.</param>
private static void TranslateCustomOperators(ref string expression, bool rightAssociative)
{
char? @operator = expression.GetOperator(rightAssociative);
if (@operator == null)
{
return;
}
int operatorIndex;
if (rightAssociative)
{
operatorIndex = expression.LastIndexOf(@operator.Value);
}
else
{
operatorIndex = expression.IndexOf(@operator.Value);
}
int leftIndex = operatorIndex - 1;
int rightIndex = operatorIndex + 1;
double?left = null;
double?right = null;
int replaceLeftIndex = -1;
int replaceRightIndex = -1;
bool isLeftSideExpression = false;
bool hasLeftSideOperator = false;
bool isRightSideExpression = false;
bool hasRightSideOperator = false;
while (leftIndex >= 0)
{
var ls = expression.Substring(leftIndex, operatorIndex - leftIndex).Replace(" ", string.Empty);
if (ls.Contains(')'))
{
isLeftSideExpression = true;
}
if (ls.Contains('+') || ls.Contains('-') || ls.Contains('*') || ls.Contains('/'))
{
hasLeftSideOperator = true;
}
if (hasLeftSideOperator && !isLeftSideExpression)
{
break;
}
double?computed = null;
try
{
computed = Operations.Compute(ls);
left = computed.Value;
replaceLeftIndex = leftIndex;
}
catch (Exception)
{
if (left != null)
{
break;
}
}
leftIndex--;
}
while (rightIndex < expression.Length)
{
var rs = expression.Substring(operatorIndex + 1, rightIndex - operatorIndex).Replace(" ", string.Empty);
if (rs.Contains(')'))
{
isRightSideExpression = true;
}
if (rs.Contains('+') || rs.Contains('-') || rs.Contains('*') || rs.Contains('/'))
{
hasRightSideOperator = true;
}
if (hasRightSideOperator && !isRightSideExpression)
{
break;
}
double?computed = null;
try
{
computed = Operations.Compute(rs);
right = computed.Value;
replaceRightIndex = rightIndex;
}
catch (Exception)
{
if (right != null)
{
break;
}
}
rightIndex++;
}
if (left != null && right != null)
{
var textToReplace = expression.Substring(replaceLeftIndex, replaceRightIndex - replaceLeftIndex + 1);
string result;
if (rightAssociative)
{
result = Custom.RightAssociativeOperators[@operator.Value].Invoke(left.Value, right.Value).ToString();
}
else
{
result = Custom.LeftAssociativeOperators[@operator.Value].Invoke(left.Value, right.Value).ToString();
}
expression = expression.Replace(textToReplace, result);
TranslateCustomOperators(ref expression, rightAssociative);
}
}
