Extensions
Contains the LINQ to JSON extension methods.
            
                using Newtonsoft.Json.Utilities;
using Newtonsoft.Json.Utilities.LinqBridge;
using System;
using System.Collections.Generic;
using System.Globalization;
namespace Newtonsoft.Json.Linq
{
    public static class Extensions
    {
        public static IJEnumerable<JToken> Ancestors<T>(this IEnumerable<T> source) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((T j) => j.Ancestors()).AsJEnumerable();
        }
        public static IJEnumerable<JToken> AncestorsAndSelf<T>(this IEnumerable<T> source) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((T j) => j.AncestorsAndSelf()).AsJEnumerable();
        }
        public static IJEnumerable<JToken> Descendants<T>(this IEnumerable<T> source) where T : JContainer
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((T j) => j.Descendants()).AsJEnumerable();
        }
        public static IJEnumerable<JToken> DescendantsAndSelf<T>(this IEnumerable<T> source) where T : JContainer
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((T j) => j.DescendantsAndSelf()).AsJEnumerable();
        }
        public static IJEnumerable<JProperty> Properties(this IEnumerable<JObject> source)
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((JObject d) => d.Properties()).AsJEnumerable();
        }
        public static IJEnumerable<JToken> Values(this IEnumerable<JToken> source, object key)
        {
            return source.Values<JToken, JToken>(key).AsJEnumerable();
        }
        public static IJEnumerable<JToken> Values(this IEnumerable<JToken> source)
        {
            return source.Values(null);
        }
        public static IEnumerable<U> Values<U>(this IEnumerable<JToken> source, object key)
        {
            return source.Values<JToken, U>(key);
        }
        public static IEnumerable<U> Values<U>(this IEnumerable<JToken> source)
        {
            return source.Values<JToken, U>(null);
        }
        public static U Value<U>(this IEnumerable<JToken> value)
        {
            return value.Value<JToken, U>();
        }
        public static U Value<T, U>(this IEnumerable<T> value) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(value, "value");
            JToken obj = value as JToken;
            if (obj == null)
                throw new ArgumentException("Source value must be a JToken.");
            return obj.Convert<JToken, U>();
        }
        internal static IEnumerable<U> Values<T, U>(this IEnumerable<T> source, object key) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            if (key == null) {
                foreach (T item in source) {
                    JValue token;
                    if ((token = (item as JValue)) != null)
                        yield return Extensions.Convert<JValue, U>(token);
                    else {
                        foreach (JToken item2 in item.Children()) {
                            yield return Extensions.Convert<JToken, U>(item2);
                        }
                    }
                }
            } else {
                foreach (T item3 in source) {
                    JToken jToken = item3[key];
                    if (jToken != null)
                        yield return Extensions.Convert<JToken, U>(jToken);
                }
            }
        }
        public static IJEnumerable<JToken> Children<T>(this IEnumerable<T> source) where T : JToken
        {
            return source.Children<T, JToken>().AsJEnumerable();
        }
        public static IEnumerable<U> Children<T, U>(this IEnumerable<T> source) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            return source.SelectMany((T c) => c.Children()).Convert<JToken, U>();
        }
        internal static IEnumerable<U> Convert<T, U>(this IEnumerable<T> source) where T : JToken
        {
            ValidationUtils.ArgumentNotNull(source, "source");
            foreach (T item in source) {
                yield return Extensions.Convert<JToken, U>((JToken)item);
            }
        }
        internal static U Convert<T, U>(this T token) where T : JToken
        {
            if (token == null)
                return default(U);
            T val;
            if ((val = token) is U) {
                U result = (U)(object)val;
                if ((object)typeof(U) != typeof(IComparable) && (object)typeof(U) != typeof(IFormattable))
                    return result;
            }
            JValue jValue;
            if ((jValue = (token as JValue)) == null)
                throw new InvalidCastException("Cannot cast {0} to {1}.".FormatWith(CultureInfo.InvariantCulture, token.GetType(), typeof(T)));
            object value;
            if ((value = jValue.Value) is U)
                return (U)value;
            Type type = typeof(U);
            if (ReflectionUtils.IsNullableType(type)) {
                if (jValue.Value == null)
                    return default(U);
                type = Nullable.GetUnderlyingType(type);
            }
            return (U)System.Convert.ChangeType(jValue.Value, type, CultureInfo.InvariantCulture);
        }
        public static IJEnumerable<JToken> AsJEnumerable(this IEnumerable<JToken> source)
        {
            return source.AsJEnumerable<JToken>();
        }
        public static IJEnumerable<T> AsJEnumerable<T>(this IEnumerable<T> source) where T : JToken
        {
            if (source == null)
                return null;
            IJEnumerable<T> result;
            if ((result = (source as IJEnumerable<T>)) != null)
                return result;
            return new JEnumerable<T>(source);
        }
    }
}