/// <summary>
/// Validates and returns a fact.
///
/// Throws an exception if the id is not in Facts.cs or if the
/// value cannot be parsed to the type specified in Facts.cs
///
/// </summary>
/// <param name="id"></param>
/// <param name="value"></param>
/// <returns></returns>
private static Fact ParseFact(string id, string value)
{
var fact = new Fact()
{
Id = id
};
// Validate id (must be defined in Facts.cs)
var valueType = Facts.GetType(id);
// Validate value (must be parsable to type specified in Facts)
if (valueType == typeof(string))
{
fact.Value = new StringValue(value);
if (fact.Value.GetValue() == null)
{
throw new RulesException("Failed to parse string value");
}
}
else if (valueType == typeof(int))
{
fact.Value = new IntValue(value);
if (fact.Value.GetValue() == null)
{
throw new RulesException("Failed to parse int value");
}
}
else if (valueType == typeof(decimal))
{
fact.Value = new DecimalValue(value);
if (fact.Value.GetValue() == null)
{
throw new RulesException("Failed to parse decimal value");
}
}
else if (valueType == typeof(bool))
{
fact.Value = new BoolValue(value);
if (fact.Value.GetValue() == null)
{
throw new RulesException("Failed to parse bool value");
}
}
else
{
throw new RulesException("Don't know how to parse value");
}
return(fact);
}
private static Condition ReadCondition(YamlNode node)
{
// Read condition
var yamlCondition = GetYamlString(node);
if (yamlCondition == null)
{
throw new RulesException($"Expected a condition (string) but found: {node}");
}
Condition.Oper?oper = null;
var condition = new Condition();
// Parse condition (allow 3rd token to contain spaces)
var tokens = yamlCondition.Split(" ", 3);
if (tokens.Length == 1)
{
// Special prefixes & (IsDefined) and ! (NotDefined)
if (tokens[0][0] == '&' || tokens[0][0] == '!')
{
oper = tokens[0][0] == '&' ? Condition.Oper.IsDefined : Condition.Oper.NotDefined;
condition.Id = tokens[0].Substring(1);
// Validate id (must be defined in Facts.cs)
Facts.GetType(condition.Id);
}
else
{
// Boolean Combiners (And/Or)
var boolOp = tokens[0].ToLower();
if (boolOp == "and")
{
oper = Condition.Oper.And;
}
else if (boolOp == "or")
{
oper = Condition.Oper.Or;
}
}
}
else if (tokens.Length == 3)
{
switch (tokens[1])
{
case "==":
oper = Condition.Oper.Equal;
break;
case "!=":
oper = Condition.Oper.NotEqual;
break;
case "<":
oper = Condition.Oper.LessThan;
break;
case ">":
oper = Condition.Oper.GreaterThan;
break;
case "<=":
oper = Condition.Oper.LessThanOrEqual;
break;
case ">=":
oper = Condition.Oper.GreaterThanOrEqual;
break;
default:
break;
}
try
{
var fact = ParseFact(tokens[0], tokens[2]);
condition.Id = fact.Id;
condition.Value = fact.Value;
}
catch (RulesException ex)
{
throw new RulesException($"{ex.Message} in condition: {yamlCondition}");
}
}
if (oper == null)
{
throw new RulesException($"Expected condition in format: 'AND', 'OR', '!id', 'id [==|!=|<|>|<=|>=] value' but found: {yamlCondition}");
}
condition.Op = oper ?? Condition.Oper.Equal;
return(condition);
}
