/// <summary>
/// Gets a list of the sub expressions.
/// </summary>
/// <param name="expression">The root expression.</param>
/// <returns>List of the sub expressions</returns>
private IEnumerable <CustomExpression> GetChildren(CustomExpression expression)
{
if (expression.InnerExpression != null)
{
yield return(expression.InnerExpression);
var children = this.GetChildren(expression.InnerExpression);
foreach (var child in children)
{
yield return(child);
}
}
}
/// <summary>
/// Pre-calculates the extra functions (defined at the <see cref="Custom.Functions"/> class) for a given math expression.
/// </summary>
/// <param name="expression">The math expression to translate.</param>
private static void TranslateCustomFunctions(ref string expression)
{
var copy = expression;
var functionName = expression.GetRootFunctionName();
if (functionName == null)
{
// The expression does not contains custom function.
return;
}
var extracted = ExtractFunctions(expression);
foreach (var item in extracted)
{
if (item.ArgumentValue.HasValue)
{
// The function argument is already simplified.
expression = expression.Replace(item.Argument, item.ArgumentValue.Value.ToString());
}
else
{
// This function must be simplified.
expression = expression.Replace(item.Expression, item.Simplify());
}
}
var expressions = expression.Split(
new string[] { " + ", " - ", " * ", " / " },
StringSplitOptions.RemoveEmptyEntries);
var operators = expression.Split(expressions, StringSplitOptions.RemoveEmptyEntries);
var newExpressions = new List <string>();
var customFunctionNames = Custom.Functions.Keys;
foreach (var expr in expressions)
{
var fname = expr.GetRootFunctionName();
if (fname != null)
{
var customExpr = new CustomExpression(expr);
var simplified = customExpr.Simplify();
newExpressions.Add(simplified);
}
else
{
newExpressions.Add(expr);
}
}
if (newExpressions.Count - 1 != operators.Length)
{
throw new InvalidProgramException(
"The simplification of the expression failed!");
}
// Building the output expression
string simplifiedExpression = string.Empty;
for (int i = 0; i < newExpressions.Count; i++)
{
simplifiedExpression += newExpressions[i];
if (i < operators.Length)
{
simplifiedExpression += operators[i];
}
}
expression = simplifiedExpression;
}