SpecificationPropertyExtensions.cs

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// Copyright 2005-2015 Giacomo Stelluti Scala & Contributors. All rights reserved. See License.md in the project root for license information.
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
 
using CSharpx;
 
namespace CommandLine.Core
{
    internal static class SpecificationPropertyExtensions
    {
        public static SpecificationProperty WithSpecification(this SpecificationProperty specProp,
                                                              Specification newSpecification)
        {
            if (newSpecification == null)
            {
                throw new ArgumentNullException(nameof(newSpecification));
            }
 
            return SpecificationProperty.Create(newSpecification, specProp.Property, specProp.Value);
        }
 
        public static SpecificationProperty WithValue(this SpecificationProperty specProp, Maybe<object> newValue)
        {
            if (newValue == null)
            {
                throw new ArgumentNullException(nameof(newValue));
            }
 
            return SpecificationProperty.Create(specProp.Specification, specProp.Property, newValue);
        }
 
        public static Type GetConversionType(this SpecificationProperty specProp)
        {
            switch (specProp.Specification.TargetType)
            {
                case TargetType.Sequence:
                    return specProp.Property.PropertyType.GetTypeInfo()
                                   .GetGenericArguments()
                                   .SingleOrDefault()
                                   .ToMaybe()
                                   .FromJustOrFail(new
                                                       InvalidOperationException("Sequence properties should be of type IEnumerable<T>."
                                                           )
                                                  );
                default:
                    return specProp.Property.PropertyType;
            }
        }
 
        public static IEnumerable<Error> Validate(this IEnumerable<SpecificationProperty> specProps,
                                                  IEnumerable<Func<IEnumerable<SpecificationProperty>,
                                                      IEnumerable<Error>>> rules)
        {
            return rules.SelectMany(rule => rule(specProps));
        }
    }
}