public static Expression <Func <TValue, bool> > CreateExpression <TValue>(
Expression <Func <TValue, bool> > expressionA,
Expression expressionB,
ParameterExpression parameter,
LambdaMerge typeMerge) where TValue : class
{
var predicate = expressionB.CreateExpression <TValue>(parameter);
if (expressionA.IsNull())
{
return(predicate);
}
var expressionsJoined = JoinExpressions(expressionA, predicate, parameter, typeMerge);
return(expressionsJoined);
}
private static Expression <Func <TValue, bool> > JoinExpressions <TValue>(
Expression <Func <TValue, bool> > predicateA,
Expression <Func <TValue, bool> > predicateB,
ParameterExpression parameter,
LambdaMerge typeMerge) where TValue : class
{
if (typeMerge == LambdaMerge.And)
{
var expression = AndAlso(predicateA, predicateB, parameter);
return(expression.CreateExpression <TValue>(parameter));
}
else
{
var expression = OrElse(predicateA, predicateB, parameter);
return(CreateExpression <TValue>(expression, parameter));
}
}
private static Expression <Func <TValue, bool> > MergeExpressions <TValue>(
this Expression <Func <TValue, bool> > predicate,
LambdaMerge typeMerge,
ParameterExpression parameter,
Expression <Func <TValue, bool> > predicateMerge)
where TValue : class
{
Expression lambda;
if (typeMerge == LambdaMerge.And)
{
lambda = Expression.AndAlso(
Expression.Invoke(predicate, parameter),
Expression.Invoke(predicateMerge, parameter));
}
else
{
lambda = Expression.OrElse(
Expression.Invoke(predicate, parameter),
Expression.Invoke(predicateMerge, parameter));
}
return(Expression.Lambda <Func <TValue, bool> >(lambda, parameter));
}
