public IExpressionSpecification <TModel> Apply <TModel>(IExpressionSpecification <TModel> specification)
{
var candidateExpr = specification.Expression.Parameters[0];
var body = Expression.Not(specification.Expression.Body);
var resultExpression = Expression.Lambda <Func <TModel, bool> >(body, candidateExpr);
var combinedSpecification = new DynamicExpressionSpecification <TModel>(resultExpression);
return(combinedSpecification);
}
// https://stackoverflow.com/questions/457316/combining-two-expressions-expressionfunct-bool
public IExpressionSpecification <TModel> Combine <TModel>(IExpressionSpecification <TModel> left, IExpressionSpecification <TModel> right)
{
Expression <Func <TModel, bool> > resultExpression;
var param = left.Expression.Parameters.First();
if (ReferenceEquals(param, right.Expression.Parameters.First()))
{
resultExpression = Expression.Lambda <Func <TModel, bool> >(
Expression.AndAlso(left.Expression.Body, right.Expression.Body), param);
}
else
{
resultExpression = Expression.Lambda <Func <TModel, bool> >(
Expression.AndAlso(
left.Expression.Body,
Expression.Invoke(right.Expression, param)), param);
}
var combinedSpecification = new DynamicExpressionSpecification <TModel>(resultExpression);
return(combinedSpecification);
}
