Context.Dictionary.cs

using System;
using System.Collections;
using System.Collections.Generic;

namespace Polly
{
    /// <summary>
    /// Context that carries with a single execution through a Policy.   Commonly-used properties are directly on the class.  Backed by a dictionary of string key / object value pairs, to which user-defined values may be added.
    /// <remarks>Do not re-use an instance of <see cref="Context"/> across more than one execution.</remarks>
    /// </summary>
    public partial class Context : IDictionary<string, object>, IDictionary
#if !NET40
        , IReadOnlyDictionary<string, object>
#endif
    {
        // For an individual execution through a policy or policywrap, it is expected that all execution steps (for example executing the user delegate, invoking policy-activity delegates such as onRetry, onBreak, onTimeout etc) execute sequentially.  
        // Therefore, this class is intentionally not constructed to be safe for concurrent access from multiple threads.

        private Dictionary<string, object> wrappedDictionary = null;

        private Dictionary<string, object> WrappedDictionary => wrappedDictionary ?? (wrappedDictionary = new Dictionary<string, object>());

        /// <summary>
        /// Initializes a new instance of the <see cref="Context"/> class, with the specified <paramref name="operationKey" /> and the supplied <paramref name="contextData"/>.
        /// </summary>
        /// <param name="operationKey">The operation key.</param>
        /// <param name="contextData">The context data.</param>
        public Context(String operationKey, IDictionary<string, object> contextData) : this(contextData)
        {
            OperationKey = operationKey;
        }

        internal Context(IDictionary<string, object> contextData) : this()
        {
            if (contextData == null) throw new ArgumentNullException(nameof(contextData));
            wrappedDictionary = new Dictionary<string, object>(contextData);
        }

#region IDictionary<string,object> implementation

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public ICollection<string> Keys => WrappedDictionary.Keys;

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public ICollection<object> Values => WrappedDictionary.Values;

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public int Count => WrappedDictionary.Count;

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        bool ICollection<KeyValuePair<string, object>>.IsReadOnly => ((IDictionary<string, object>)WrappedDictionary).IsReadOnly;

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public object this[string key]
        {
            get => WrappedDictionary[key];
            set => WrappedDictionary[key] = value;
        }

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public void Add(string key, object value)
        {
            WrappedDictionary.Add(key, value);
        }

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public bool ContainsKey(string key) => WrappedDictionary.ContainsKey(key);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public bool Remove(string key) => WrappedDictionary.Remove(key);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public bool TryGetValue(string key, out object value) => WrappedDictionary.TryGetValue(key, out value);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        void ICollection<KeyValuePair<string, object>>.Add(KeyValuePair<string, object> item) => ((IDictionary<string, object>)WrappedDictionary).Add(item);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public void Clear() => WrappedDictionary.Clear();

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        bool ICollection<KeyValuePair<string, object>>.Contains(KeyValuePair<string, object> item) => ((IDictionary<string, object>)WrappedDictionary).Contains(item);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        void ICollection<KeyValuePair<string, object>>.CopyTo(KeyValuePair<string, object>[] array, int arrayIndex) => ((IDictionary<string, object>) WrappedDictionary).CopyTo(array, arrayIndex);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        bool ICollection<KeyValuePair<string, object>>.Remove(KeyValuePair<string, object> item) => ((IDictionary<string, object>)WrappedDictionary).Remove(item);

        /// <inheritdoc cref="IDictionary{TKey,Value}"/>
        public IEnumerator<KeyValuePair<string, object>> GetEnumerator() => WrappedDictionary.GetEnumerator();

        /// <inheritdoc cref="IDictionary{TKey,Value}"/> 
        IEnumerator IEnumerable.GetEnumerator() => WrappedDictionary.GetEnumerator();

        /// <inheritdoc cref="IDictionary"/> 
        public void Add(object key, object value)
        {
            ((IDictionary)WrappedDictionary).Add(key, value);
        }

        /// <inheritdoc cref="IDictionary"/> 
        public bool Contains(object key)
        {
            return ((IDictionary)WrappedDictionary).Contains(key);
        }

        /// <inheritdoc cref="IDictionary"/> 
        IDictionaryEnumerator IDictionary.GetEnumerator()
        {
            return ((IDictionary)WrappedDictionary).GetEnumerator();
        }

        /// <inheritdoc cref="IDictionary"/> 
        public void Remove(object key)
        {
            ((IDictionary)WrappedDictionary).Remove(key);
        }

        /// <inheritdoc cref="IDictionary"/> 
        public void CopyTo(Array array, int index)
        {
            ((IDictionary)WrappedDictionary).CopyTo(array, index);
        }

        #endregion

#if !NET40
        #region IReadOnlyDictionary<string, object> implementation
        IEnumerable<string> IReadOnlyDictionary<string, object>.Keys => ((IReadOnlyDictionary<string, object>)WrappedDictionary).Keys;

        IEnumerable<object> IReadOnlyDictionary<string, object>.Values => ((IReadOnlyDictionary<string, object>)WrappedDictionary).Values;
        #endregion
#endif

        #region IDictionary implementation

        /// <inheritdoc cref="IDictionary"/> 
        bool IDictionary.IsFixedSize => ((IDictionary)WrappedDictionary).IsFixedSize;

        /// <inheritdoc cref="IDictionary"/> 
        bool IDictionary.IsReadOnly => ((IDictionary)WrappedDictionary).IsReadOnly;

        ICollection IDictionary.Keys => ((IDictionary)WrappedDictionary).Keys;

        ICollection IDictionary.Values => ((IDictionary)WrappedDictionary).Values;

        /// <inheritdoc cref="IDictionary"/> 
        bool ICollection.IsSynchronized => ((IDictionary)WrappedDictionary).IsSynchronized;

        /// <inheritdoc cref="IDictionary"/> 
        object ICollection.SyncRoot => ((IDictionary)WrappedDictionary).SyncRoot;

        /// <inheritdoc cref="IDictionary"/> 
        object IDictionary.this[object key] { get => ((IDictionary)WrappedDictionary)[key]; set => ((IDictionary)WrappedDictionary)[key] = value; }

#endregion
    }
}