/// <summary>
/// Instantiates a new Formula predicate.
/// </summary>
/// <param name="resolutionType">The type of resolution for the formula.</param>
/// <param name="bob">The business object binder to use when evaluating the formula, or null.</param>
/// <param name="expression">The expression value, i.e. the C# code source that should be computable.</param>
/// <param name="evaluator">A precompiled evaluator, or null.</param>
private Formula(FormulaResolutionType resolutionType, IBinder bob, string expression, IDictionaryEvaluator evaluator)
: base(expression)
{
this.resolutionType = resolutionType;
this.bob = bob;
this.expression = expression;
this.evaluator = evaluator;
this.formulaSignature = null;
}
/// <summary>
/// Evaluate the current Formula with a passed list of arguments.
/// </summary>
/// <param name="arguments">The name/value pairs of arguments.</param>
/// <returns>An object representing the value of the Formula.</returns>
public object Evaluate(IDictionary arguments)
{
if (resolutionType == FormulaResolutionType.NxBRE) {
if (evaluator == null) evaluator = Compilation.NewEvaluator(expression,
DEFAULT_EXPRESSION_PLACEHOLDER,
DEFAULT_NUMERIC_ARGUMENT_PATTERN,
arguments);
return evaluator.Run(arguments);
}
else if (resolutionType == FormulaResolutionType.Binder) {
if (formulaSignature == null) formulaSignature = Parameter.BuildFormulaSignature(expression);
// if arguments have been passed in the formula signature, pass them to the binder as
// a special entry in the arguments IDictionary (this approach has been preferred to modifying the
// Compute method signature which would have broken this compatibility
if (formulaSignature.Arguments.Count > 0) arguments.Add(typeof(Parameter), formulaSignature.Arguments);
return bob.Compute(formulaSignature.Name, arguments);
}
else
throw new BREException("Formula evaluation mode not supported: " + resolutionType);
}