crtr/Assets/YamlDotNet/Serialization/NodeDeserializers/DictionaryNodeDeserializer.cs

// This file is part of YamlDotNet - A .NET library for YAML.
// Copyright (c) Antoine Aubry and contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

using System;
using System.Collections;
using System.Collections.Generic;
using YamlDotNet.Core;
using YamlDotNet.Core.Events;
using YamlDotNet.Helpers;
using YamlDotNet.Serialization.Utilities;

namespace YamlDotNet.Serialization.NodeDeserializers
{
    public sealed class DictionaryNodeDeserializer : INodeDeserializer
    {
        private readonly IObjectFactory objectFactory;

        public DictionaryNodeDeserializer(IObjectFactory objectFactory)
        {
            this.objectFactory = objectFactory ?? throw new ArgumentNullException(nameof(objectFactory));
        }

        bool INodeDeserializer.Deserialize(IParser parser, Type expectedType, Func<IParser, Type, object?> nestedObjectDeserializer, out object? value)
        {
            IDictionary? dictionary;
            Type keyType, valueType;
            var genericDictionaryType = ReflectionUtility.GetImplementedGenericInterface(expectedType, typeof(IDictionary<,>));
            if (genericDictionaryType != null)
            {
                var genericArguments = genericDictionaryType.GetGenericArguments();
                keyType = genericArguments[0];
                valueType = genericArguments[1];

                value = objectFactory.Create(expectedType);

                dictionary = value as IDictionary;
                if (dictionary == null)
                {
                    // Uncommon case where a type implements IDictionary<TKey, TValue> but not IDictionary
                    dictionary = (IDictionary?)Activator.CreateInstance(typeof(GenericDictionaryToNonGenericAdapter<,>).MakeGenericType(keyType, valueType), value);
                }
            }
            else if (typeof(IDictionary).IsAssignableFrom(expectedType))
            {
                keyType = typeof(object);
                valueType = typeof(object);

                value = objectFactory.Create(expectedType);
                dictionary = (IDictionary)value;
            }
            else
            {
                value = null;
                return false;
            }

            DeserializeHelper(keyType, valueType, parser, nestedObjectDeserializer, dictionary!);

            return true;
        }

        private static void DeserializeHelper(Type tKey, Type tValue, IParser parser, Func<IParser, Type, object?> nestedObjectDeserializer, IDictionary result)
        {
            parser.Consume<MappingStart>();
            while (!parser.TryConsume<MappingEnd>(out var _))
            {
                var key = nestedObjectDeserializer(parser, tKey);
                var value = nestedObjectDeserializer(parser, tValue);
                var valuePromise = value as IValuePromise;

                if (key is IValuePromise keyPromise)
                {
                    if (valuePromise == null)
                    {
                        // Key is pending, value is known
                        keyPromise.ValueAvailable += v => result[v!] = value!;
                    }
                    else
                    {
                        // Both key and value are pending. We need to wait until both of them become available.
                        var hasFirstPart = false;

                        keyPromise.ValueAvailable += v =>
                        {
                            if (hasFirstPart)
                            {
                                result[v!] = value!;
                            }
                            else
                            {
                                key = v!;
                                hasFirstPart = true;
                            }
                        };

                        valuePromise.ValueAvailable += v =>
                        {
                            if (hasFirstPart)
                            {
                                result[key] = v!;
                            }
                            else
                            {
                                value = v;
                                hasFirstPart = true;
                            }
                        };
                    }
                }
                else
                {
                    if (valuePromise == null)
                    {
                        // Happy path: both key and value are known
                        result[key!] = value!;
                    }
                    else
                    {
                        // Key is known, value is pending
                        valuePromise.ValueAvailable += v => result[key!] = v!;
                    }
                }
            }
        }
    }
}