public string RunOnEntity(Entity entity, Entity.Attribute attribute = null)
{
References = new List <Entity.Attribute>();
MissingReferences = new List <string>();
StringOrError result = ParseAndExecute(entity, attribute);
if (MissingReferences.Count != 0)
{
return($"Could not find groups {string.Join(", ", MissingReferences)}");
}
return(result.Value);
}
private StringOrError ParseAndExecute(Entity entity, Entity.Attribute attribute)
{
string formula = Formula.Trim();
// Check if the formula is empty
if (string.IsNullOrEmpty(formula))
{
return(new StringOrError(false, ""));
}
// Check if the formula is a literal
var matchString = Regex.Match(formula, "(\"([^\"]*)\")|(\'([^\']*)\')");
if (matchString.Success && matchString.Value == formula)
{
return(new StringOrError(false, matchString.Groups[2].Value));
}
var matchDecimal = Regex.Match(formula, "-?[0-9]+(\\.[0-9]+)?");
if (matchDecimal.Success && matchDecimal.Value == formula)
{
return(new StringOrError(false, matchDecimal.Value));
}
// Check if it is referencing another group
var matchReference = Regex.Match(formula, @"&([^^&""\(\)\+\-\\,]+)"); // Any name ommiting special characters
if (matchReference.Success && matchReference.Value == formula)
{
string groupName = matchReference.Groups[1].Value;
Entity.Attribute referencedAttribute = entity.Attributes.FirstOrDefault(x => x.GroupName == groupName);
if (referencedAttribute == null) // If attribute by the name groupName doesn't exist
{
MissingReferences.Add(groupName);
return(new StringOrError(true, $"Could not find attribute '{groupName}'"));
}
else // If reference is to an existing attribute
{
References.Add(referencedAttribute);
switch (referencedAttribute.GetAttributeType())
{
case Entity.AttributeType.Image:
return(new StringOrError(true, $"Cannot convert image attribute '{groupName}' to string"));
case Entity.AttributeType.Formula:
if (attribute != null)
{
List <Entity.Attribute> referenceReferences = ((Entity.FormulaAttribute)referencedAttribute).Formula.References;
if (referenceReferences.Contains(attribute)) // Can't have looping dependencies
{
return(new StringOrError(true, $"Circular reference with '{groupName}'"));
}
References.AddRange(referenceReferences);
}
break;
}
return(new StringOrError(false, (string)referencedAttribute.GetListViewValue()));
}
}
// Check for monads
var monadReference = Regex.Match(formula, @"([a-zA-Z]+)\(([^,]+)\)");
if (monadReference.Success && monadReference.Value == formula)
{
return(new StringOrError(true, $"Could not parse monad '{formula}'"));
}
// Check for diads
var diadReference = Regex.Match(formula, @"([a-zA-Z]+)\(([^,]+),([^,]+)\)");
if (diadReference.Success && diadReference.Value == formula)
{
string functionName = diadReference.Groups[1].Value.ToLower();
Expression leftExp = new Expression(diadReference.Groups[2].Value);
StringOrError left = leftExp.ParseAndExecute(entity, attribute);
References.AddRange(leftExp.References);
MissingReferences.AddRange(leftExp.MissingReferences);
if (left.IsError)
{
return(left);
}
Expression rightExp = new Expression(diadReference.Groups[3].Value);
StringOrError right = rightExp.ParseAndExecute(entity, attribute);
References.AddRange(rightExp.References);
MissingReferences.AddRange(rightExp.MissingReferences);
if (right.IsError)
{
return(right);
}
if (functionName == "add" || functionName == "sub" || functionName == "mult" || functionName == "div" || functionName == "gt" || functionName == "lt")
{
bool isLeftInt = decimal.TryParse(left.Value, out decimal leftDec);
bool isRightInt = decimal.TryParse(right.Value, out decimal rightDec);
if (!isLeftInt || !isRightInt)
{
return(new StringOrError(true, $"Could not parse '{(isLeftInt ? left.Value : right.Value)}' to an decimal in formula '{formula}'"));
}
if (functionName == "add")
{
return(new StringOrError(false, (leftDec + rightDec).ToString()));
}
if (functionName == "sub")
{
return(new StringOrError(false, (leftDec - rightDec).ToString()));
}
if (functionName == "mult")
{
return(new StringOrError(false, (leftDec * rightDec).ToString()));
}
if (functionName == "div")
{
if (rightDec == 0M)
{
return(new StringOrError(true, $"Could not divide by 0 in '{formula}'"));
}
return(new StringOrError(false, (leftDec / rightDec).ToString()));
}
if (functionName == "gt")
{
return(new StringOrError(false, (leftDec > rightDec).ToString()));
}
if (functionName == "lt")
{
return(new StringOrError(false, (leftDec < rightDec).ToString()));
}
}
if (functionName == "eq")
{
return(new StringOrError(false, (left.Value == right.Value).ToString()));
}
}
return(new StringOrError(true, $"Could not parse expression '{formula}'"));
}
