public override Expression BuildExpression(params ParameterExpression[] parameters)
{
if (parameters == null || parameters.Length != 1 || parameters[0].Type != typeof(T))
{
throw new RuleEngineException($"{nameof(BuildExpression)} must call with one parameter of {typeof(T)}");
}
var conditionalExpression = ConditionRule.BuildExpression(parameters);
if (!(conditionalExpression is LambdaExpression))
{
conditionalExpression = Expression.Lambda(conditionalExpression, parameters);
}
var trueExpression = TrueRule.BuildExpression(parameters);
if (!(trueExpression is LambdaExpression))
{
trueExpression = Expression.Lambda(trueExpression, parameters);
}
var falseExpression = FalseRule.BuildExpression(parameters);
if (!(falseExpression is LambdaExpression))
{
falseExpression = Expression.Lambda(falseExpression, parameters);
}
ExpressionForThisRule = Expression.Condition(Expression.Invoke(conditionalExpression, parameters.Cast <Expression>()),
Expression.Invoke(trueExpression, parameters.Cast <Expression>()),
Expression.Invoke(falseExpression, parameters.Cast <Expression>()));
return(ExpressionForThisRule);
}
public void Matches()
{
var rule = new FalseRule();
var result = rule.Matches(null, null);
Assert.AreEqual(false, result);
}
public override Expression BuildExpression(params ParameterExpression[] parameters)
{
if (parameters == null || parameters.Length != 1 || parameters[0].Type != typeof(T1))
{
throw new RuleEngineException($"{nameof(BuildExpression)} must call with one parameter of {typeof(T1)}");
}
var returnLabel = Expression.Label(typeof(T2), "returnLabel");
var conditionalExpression = ConditionRule.BuildExpression(parameters);
if (!(conditionalExpression is LambdaExpression))
{
conditionalExpression = Expression.Lambda(conditionalExpression, parameters);
}
var trueExpression = TrueRule.BuildExpression(parameters);
if (!(trueExpression is LambdaExpression))
{
trueExpression = Expression.Lambda(trueExpression, parameters);
}
var falseExpression = FalseRule.BuildExpression(parameters);
if (!(falseExpression is LambdaExpression))
{
falseExpression = Expression.Lambda(falseExpression, parameters);
}
var ifThenElseExpression = Expression.IfThenElse(
Expression.Invoke(conditionalExpression, parameters.Cast <Expression>()),
Expression.Return(returnLabel, Expression.Invoke(trueExpression, parameters.Cast <Expression>())),
Expression.Return(returnLabel, Expression.Invoke(falseExpression, parameters.Cast <Expression>()))
);
Debug.WriteLine($"ConditionRule:{Environment.NewLine}{ConditionRule.ExpressionDebugView()}");
Debug.WriteLine($"TrueRule:{Environment.NewLine}{TrueRule.ExpressionDebugView()}");
Debug.WriteLine($"FalseRule:{Environment.NewLine}{FalseRule.ExpressionDebugView()}");
var defaultForReturnLabel = Expression.Convert(Expression.Constant(default(T2)), typeof(T2));
ExpressionForThisRule = Expression.Block(ifThenElseExpression,
Expression.Label(returnLabel, defaultForReturnLabel));
return(ExpressionForThisRule);
}