RSCG – System.Text.Json

 
 

name System.Text.Json
nuget https://www.nuget.org/packages/System.Text.Json/
link https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/source-generation
author Microsoft

Json Serialize without reflection

 

This is how you can use System.Text.Json .

The code that you start with is

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<Project Sdk="Microsoft.NET.Sdk">
 
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
    <PropertyGroup>
        <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
        <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GeneratedX</CompilerGeneratedFilesOutputPath>
    </PropertyGroup>
 
</Project>

The code that you will use is

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using JsonSerializerOptionsExample;
using System.Text.Json;
//for asp.net core
//services.AddControllers().AddJsonOptions(options => options.JsonSerializerOptions.AddContext<MyJsonContext>());
//https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/raw-string
 
string jsonString ="""
{
  "date": "2019-08-01T00:00:00",
  "temperatureCelsius": 25,
  "summary": "Hot"
}
""";
        WeatherForecast? weatherForecast= JsonSerializer.Deserialize(
            jsonString,
            typeof(WeatherForecast),
            new OptionsExampleContext(
                new JsonSerializerOptions(JsonSerializerDefaults.Web)))
                as WeatherForecast;
        Console.WriteLine($"Date={weatherForecast?.Date}");
        // output:
        //Date=8/1/2019 12:00:00 AM
 
        jsonString = JsonSerializer.Serialize(
            weatherForecast,
            typeof(WeatherForecast),
            new OptionsExampleContext(
                new JsonSerializerOptions(JsonSerializerDefaults.Web)));
        Console.WriteLine(jsonString);
jsonString = JsonSerializer.Serialize(
    weatherForecast,
    typeof(WeatherForecast),
    new OptionsExampleContext(
        new JsonSerializerOptions(JsonSerializerDefaults.General)));
Console.WriteLine(jsonString);
// output:
//{ "date":"2019-08-01T00:00:00","temperatureCelsius":25,"summary":"Hot"}
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namespace JsonSerializerOptionsExample;
 
public class WeatherForecast
{
    public DateTime Date { get; set; }
    public int TemperatureCelsius { get; set; }
    public string? Summary { get; set; }
}
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using System.Text.Json.Serialization;
 
namespace JsonSerializerOptionsExample;
 
[JsonSerializable(typeof(WeatherForecast))]
internal partial class OptionsExampleContext : JsonSerializerContext
{
}

 

The code that is generated is

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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.DateTime>? _DateTime;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.DateTime> DateTime
        {
            get => _DateTime ??= Create_DateTime(Options, makeReadOnly: true);
        }
         
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.DateTime> Create_DateTime(global::System.Text.Json.JsonSerializerOptions options, bool makeReadOnly)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.DateTime>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::System.DateTime))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.DateTime>(options, customConverter);
            }
            else
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.DateTime>(options, global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.DateTimeConverter);
            }
         
            if (makeReadOnly)
            {
                jsonTypeInfo.MakeReadOnly();
            }
         
            return jsonTypeInfo;
        }
         
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
     
    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.Json.SourceGeneration", "7.0.8.17405")]
    internal partial class OptionsExampleContext
    {
         
        private static global::System.Text.Json.JsonSerializerOptions s_defaultOptions { get; } = new global::System.Text.Json.JsonSerializerOptions()
        {
            DefaultIgnoreCondition = global::System.Text.Json.Serialization.JsonIgnoreCondition.Never,
            IgnoreReadOnlyFields = false,
            IgnoreReadOnlyProperties = false,
            IncludeFields = false,
            WriteIndented = false,
        };
         
        private static global::JsonSerializerOptionsExample.OptionsExampleContext? s_defaultContext;
         
        /// <summary>
        /// The default <see cref="global::System.Text.Json.Serialization.JsonSerializerContext"/> associated with a default <see cref="global::System.Text.Json.JsonSerializerOptions"/> instance.
        /// </summary>
        public static global::JsonSerializerOptionsExample.OptionsExampleContext Default => s_defaultContext ??= new global::JsonSerializerOptionsExample.OptionsExampleContext(new global::System.Text.Json.JsonSerializerOptions(s_defaultOptions));
         
        /// <summary>
        /// The source-generated options associated with this context.
        /// </summary>
        protected override global::System.Text.Json.JsonSerializerOptions? GeneratedSerializerOptions { get; } = s_defaultOptions;
         
        /// <inheritdoc/>
        public OptionsExampleContext() : base(null)
        {
        }
         
        /// <inheritdoc/>
        public OptionsExampleContext(global::System.Text.Json.JsonSerializerOptions options) : base(options)
        {
        }
         
        private static global::System.Text.Json.Serialization.JsonConverter? GetRuntimeProvidedCustomConverter(global::System.Text.Json.JsonSerializerOptions options, global::System.Type type)
        {
            global::System.Collections.Generic.IList<global::System.Text.Json.Serialization.JsonConverter> converters = options.Converters;
         
            for (int i = 0; i < converters.Count; i++)
            {
                global::System.Text.Json.Serialization.JsonConverter? converter = converters[i];
         
                if (converter.CanConvert(type))
                {
                    if (converter is global::System.Text.Json.Serialization.JsonConverterFactory factory)
                    {
                        converter = factory.CreateConverter(type, options);
                        if (converter == null || converter is global::System.Text.Json.Serialization.JsonConverterFactory)
                        {
                            throw new global::System.InvalidOperationException(string.Format("The converter '{0}' cannot return null or a JsonConverterFactory instance.", factory.GetType()));
                        }
                    }
         
                    return converter;
                }
            }
         
            return null;
        }
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext: global::System.Text.Json.Serialization.Metadata.IJsonTypeInfoResolver
    {
        /// <inheritdoc/>
        public override global::System.Text.Json.Serialization.Metadata.JsonTypeInfo GetTypeInfo(global::System.Type type)
        {
            if (type == typeof(global::JsonSerializerOptionsExample.WeatherForecast))
            {
                return this.WeatherForecast;
            }
         
            if (type == typeof(global::System.DateTime))
            {
                return this.DateTime;
            }
         
            if (type == typeof(global::System.Int32))
            {
                return this.Int32;
            }
         
            if (type == typeof(global::System.String))
            {
                return this.String;
            }
         
            return null!;
        }
         
        global::System.Text.Json.Serialization.Metadata.JsonTypeInfo? global::System.Text.Json.Serialization.Metadata.IJsonTypeInfoResolver.GetTypeInfo(global::System.Type type, global::System.Text.Json.JsonSerializerOptions options)
        {
            if (type == typeof(global::JsonSerializerOptionsExample.WeatherForecast))
            {
                return Create_WeatherForecast(options, makeReadOnly: false);
            }
         
            if (type == typeof(global::System.DateTime))
            {
                return Create_DateTime(options, makeReadOnly: false);
            }
         
            if (type == typeof(global::System.Int32))
            {
                return Create_Int32(options, makeReadOnly: false);
            }
         
            if (type == typeof(global::System.String))
            {
                return Create_String(options, makeReadOnly: false);
            }
         
            return null;
        }
         
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Int32>? _Int32;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Int32> Int32
        {
            get => _Int32 ??= Create_Int32(Options, makeReadOnly: true);
        }
         
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Int32> Create_Int32(global::System.Text.Json.JsonSerializerOptions options, bool makeReadOnly)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.Int32>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::System.Int32))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Int32>(options, customConverter);
            }
            else
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.Int32>(options, global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.Int32Converter);
            }
         
            if (makeReadOnly)
            {
                jsonTypeInfo.MakeReadOnly();
            }
         
            return jsonTypeInfo;
        }
         
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext
    {
         
        private static readonly global::System.Text.Json.JsonEncodedText PropName_Date = global::System.Text.Json.JsonEncodedText.Encode("Date");
        private static readonly global::System.Text.Json.JsonEncodedText PropName_TemperatureCelsius = global::System.Text.Json.JsonEncodedText.Encode("TemperatureCelsius");
        private static readonly global::System.Text.Json.JsonEncodedText PropName_Summary = global::System.Text.Json.JsonEncodedText.Encode("Summary");
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.String>? _String;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.String> String
        {
            get => _String ??= Create_String(Options, makeReadOnly: true);
        }
         
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.String> Create_String(global::System.Text.Json.JsonSerializerOptions options, bool makeReadOnly)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::System.String>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::System.String))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.String>(options, customConverter);
            }
            else
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::System.String>(options, global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.StringConverter);
            }
         
            if (makeReadOnly)
            {
                jsonTypeInfo.MakeReadOnly();
            }
         
            return jsonTypeInfo;
        }
         
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace JsonSerializerOptionsExample
{
    internal partial class OptionsExampleContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::JsonSerializerOptionsExample.WeatherForecast>? _WeatherForecast;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::JsonSerializerOptionsExample.WeatherForecast> WeatherForecast
        {
            get => _WeatherForecast ??= Create_WeatherForecast(Options, makeReadOnly: true);
        }
         
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::JsonSerializerOptionsExample.WeatherForecast> Create_WeatherForecast(global::System.Text.Json.JsonSerializerOptions options, bool makeReadOnly)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::JsonSerializerOptionsExample.WeatherForecast>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::JsonSerializerOptionsExample.WeatherForecast))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::JsonSerializerOptionsExample.WeatherForecast>(options, customConverter);
            }
            else
            {
                global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::JsonSerializerOptionsExample.WeatherForecast> objectInfo = new global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::JsonSerializerOptionsExample.WeatherForecast>()
                {
                    ObjectCreator = static () => new global::JsonSerializerOptionsExample.WeatherForecast(),
                    ObjectWithParameterizedConstructorCreator = null,
                    PropertyMetadataInitializer = _ => WeatherForecastPropInit(options),
                    ConstructorParameterMetadataInitializer = null,
                    NumberHandling = default,
                    SerializeHandler = WeatherForecastSerializeHandler
                };
         
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateObjectInfo<global::JsonSerializerOptionsExample.WeatherForecast>(options, objectInfo);
            }
         
            if (makeReadOnly)
            {
                jsonTypeInfo.MakeReadOnly();
            }
         
            return jsonTypeInfo;
        }
         
        private static global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] WeatherForecastPropInit(global::System.Text.Json.JsonSerializerOptions options)
        {
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] properties = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[3];
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.DateTime> info0 = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.DateTime>()
            {
                IsProperty = true,
                IsPublic = true,
                IsVirtual = false,
                DeclaringType = typeof(global::JsonSerializerOptionsExample.WeatherForecast),
                Converter = null,
                Getter = static (obj) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).Date,
                Setter = static (obj, value) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).Date = value!,
                IgnoreCondition = null,
                HasJsonInclude = false,
                IsExtensionData = false,
                NumberHandling = default,
                PropertyName = "Date",
                JsonPropertyName = null
            };
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo propertyInfo0 = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.DateTime>(options, info0);
            properties[0] = propertyInfo0;
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Int32> info1 = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Int32>()
            {
                IsProperty = true,
                IsPublic = true,
                IsVirtual = false,
                DeclaringType = typeof(global::JsonSerializerOptionsExample.WeatherForecast),
                Converter = null,
                Getter = static (obj) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).TemperatureCelsius,
                Setter = static (obj, value) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).TemperatureCelsius = value!,
                IgnoreCondition = null,
                HasJsonInclude = false,
                IsExtensionData = false,
                NumberHandling = default,
                PropertyName = "TemperatureCelsius",
                JsonPropertyName = null
            };
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo propertyInfo1 = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.Int32>(options, info1);
            properties[1] = propertyInfo1;
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.String> info2 = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.String>()
            {
                IsProperty = true,
                IsPublic = true,
                IsVirtual = false,
                DeclaringType = typeof(global::JsonSerializerOptionsExample.WeatherForecast),
                Converter = null,
                Getter = static (obj) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).Summary!,
                Setter = static (obj, value) => ((global::JsonSerializerOptionsExample.WeatherForecast)obj).Summary = value!,
                IgnoreCondition = null,
                HasJsonInclude = false,
                IsExtensionData = false,
                NumberHandling = default,
                PropertyName = "Summary",
                JsonPropertyName = null
            };
         
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo propertyInfo2 = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.String>(options, info2);
            properties[2] = propertyInfo2;
         
            return properties;
        }
         
        // Intentionally not a static method because we create a delegate to it. Invoking delegates to instance
        // methods is almost as fast as virtual calls. Static methods need to go through a shuffle thunk.
        private void WeatherForecastSerializeHandler(global::System.Text.Json.Utf8JsonWriter writer, global::JsonSerializerOptionsExample.WeatherForecast? value)
        {
            if (value == null)
            {
                writer.WriteNullValue();
                return;
            }
         
            writer.WriteStartObject();
            writer.WriteString(PropName_Date, value.Date);
            writer.WriteNumber(PropName_TemperatureCelsius, value.TemperatureCelsius);
            writer.WriteString(PropName_Summary, value.Summary);
         
            writer.WriteEndObject();
        }
    }
}
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// <auto-generated/>
 
#nullable enable annotations
#nullable disable warnings
 
// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618
 
namespace BothModesNoOptions
{
     
    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.Json.SourceGeneration", "7.0.8.17405")]
    internal partial class SourceGenerationContext
    {
         
        private static global::System.Text.Json.JsonSerializerOptions s_defaultOptions { get; } = new global::System.Text.Json.JsonSerializerOptions()
        {
            DefaultIgnoreCondition = global::System.Text.Json.Serialization.JsonIgnoreCondition.Never,
            IgnoreReadOnlyFields = false,
            IgnoreReadOnlyProperties = false,
            IncludeFields = false,
            WriteIndented = true,
        };
         
        private static global::BothModesNoOptions.SourceGenerationContext? s_defaultContext;
         
        /// <summary>
        /// The default <see cref="global::System.Text.Json.Serialization.JsonSerializerContext"/> associated with a default <see cref="global::System.Text.Json.JsonSerializerOptions"/> instance.
        /// </summary>
        public static global::BothModesNoOptions.SourceGenerationContext Default => s_defaultContext ??= new global::BothModesNoOptions.SourceGenerationContext(new global::System.Text.Json.JsonSerializerOptions(s_defaultOptions));
         
        /// <summary>
        /// The source-generated options associated with this context.
        /// </summary>
        protected override global::System.Text.Json.JsonSerializerOptions? GeneratedSerializerOptions { get; } = s_defaultOptions;
         
        /// <inheritdoc/>
        public SourceGenerationContext() : base(null)
        {
        }
         
        /// <inheritdoc/>
        public SourceGenerationContext(global::System.Text.Json.JsonSerializerOptions options) : base(options)
        {
        }
         
        private static global::System.Text.Json.Serialization.JsonConverter? GetRuntimeProvidedCustomConverter(global::System.Text.Json.JsonSerializerOptions options, global::System.Type type)
        {
            global::System.Collections.Generic.IList<global::System.Text.Json.Serialization.JsonConverter> converters = options.Converters;
         
            for (int i = 0; i < converters.Count; i++)
            {
                global::System.Text.Json.Serialization.JsonConverter? converter = converters[i];
         
                if (converter.CanConvert(type))
                {
                    if (converter is global::System.Text.Json.Serialization.JsonConverterFactory factory)
                    {
                        converter = factory.CreateConverter(type, options);
                        if (converter == null || converter is global::System.Text.Json.Serialization.JsonConverterFactory)
                        {
                            throw new global::System.InvalidOperationException(string.Format("The converter '{0}' cannot return null or a JsonConverterFactory instance.", factory.GetType()));
                        }
                    }
         
                    return converter;
                }
            }
         
            return null;
        }
    }
}
?
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// <auto-generated/>
#nullable enable
#pragma warning disable CS0162 // Unreachable code
#pragma warning disable CS0164 // Unreferenced label
#pragma warning disable CS0219 // Variable assigned but never used
 
namespace JsonSerializerOptionsExample
{
    partial class WeatherForecast
    {
        /// <remarks>
        /// Pattern explanation:<br/>
        /// <code>
        /// ○ Match with 2 alternative expressions, atomically.<br/>
        ///     ○ Match a sequence of expressions.<br/>
        ///         ○ Match a character in the set [Aa].<br/>
        ///         ○ Match a character in the set [Bb].<br/>
        ///         ○ Match a character in the set [Cc].<br/>
        ///     ○ Match a sequence of expressions.<br/>
        ///         ○ Match a character in the set [Dd].<br/>
        ///         ○ Match a character in the set [Ee].<br/>
        ///         ○ Match a character in the set [Ff].<br/>
        /// </code>
        /// </remarks>
        [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
        private static partial global::System.Text.RegularExpressions.Regex AbcOrDefGeneratedRegex() => global::System.Text.RegularExpressions.Generated.AbcOrDefGeneratedRegex_0.Instance;
    }
}
 
namespace System.Text.RegularExpressions.Generated
{
    using System;
    using System.CodeDom.Compiler;
    using System.Collections;
    using System.ComponentModel;
    using System.Globalization;
    using System.Runtime.CompilerServices;
    using System.Text.RegularExpressions;
    using System.Threading;
 
    /// <summary>Custom <see cref="Regex"/>-derived type for the AbcOrDefGeneratedRegex method.</summary>
    [GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
    file sealed class AbcOrDefGeneratedRegex_0 : Regex
    {
        /// <summary>Cached, thread-safe singleton instance.</summary>
        internal static readonly AbcOrDefGeneratedRegex_0 Instance = new();
     
        /// <summary>Initializes the instance.</summary>
        private AbcOrDefGeneratedRegex_0()
        {
            base.pattern = "abc|def";
            base.roptions = RegexOptions.IgnoreCase;
            ValidateMatchTimeout(Utilities.s_defaultTimeout);
            base.internalMatchTimeout = Utilities.s_defaultTimeout;
            base.factory = new RunnerFactory();
            base.capsize = 1;
        }
     
        /// <summary>Provides a factory for creating <see cref="RegexRunner"/> instances to be used by methods on <see cref="Regex"/>.</summary>
        private sealed class RunnerFactory : RegexRunnerFactory
        {
            /// <summary>Creates an instance of a <see cref="RegexRunner"/> used by methods on <see cref="Regex"/>.</summary>
            protected override RegexRunner CreateInstance() => new Runner();
         
            /// <summary>Provides the runner that contains the custom logic implementing the specified regular expression.</summary>
            private sealed class Runner : RegexRunner
            {
                /// <summary>Scan the <paramref name="inputSpan"/> starting from base.runtextstart for the next match.</summary>
                /// <param name="inputSpan">The text being scanned by the regular expression.</param>
                protected override void Scan(ReadOnlySpan<char> inputSpan)
                {
                    // Search until we can't find a valid starting position, we find a match, or we reach the end of the input.
                    while (TryFindNextPossibleStartingPosition(inputSpan) &&
                           !TryMatchAtCurrentPosition(inputSpan) &&
                           base.runtextpos != inputSpan.Length)
                    {
                        base.runtextpos++;
                        if (Utilities.s_hasTimeout)
                        {
                            base.CheckTimeout();
                        }
                    }
                }
         
                /// <summary>Search <paramref name="inputSpan"/> starting from base.runtextpos for the next location a match could possibly start.</summary>
                /// <param name="inputSpan">The text being scanned by the regular expression.</param>
                /// <returns>true if a possible match was found; false if no more matches are possible.</returns>
                private bool TryFindNextPossibleStartingPosition(ReadOnlySpan<char> inputSpan)
                {
                    int pos = base.runtextpos;
                    ulong charMinusLow;
                     
                    // Any possible match is at least 3 characters.
                    if (pos <= inputSpan.Length - 3)
                    {
                        // The pattern matches a character in the set [CFcf] at index 2.
                        // Find the next occurrence. If it can't be found, there's no match.
                        ReadOnlySpan<char> span = inputSpan.Slice(pos);
                        for (int i = 0; i < span.Length - 2; i++)
                        {
                            int indexOfPos = span.Slice(i + 2).IndexOfAny("CFcf");
                            if (indexOfPos < 0)
                            {
                                goto NoMatchFound;
                            }
                            i += indexOfPos;
                             
                            if (((long)((0x9000000090000000UL << (int)(charMinusLow = (uint)span[i] - 'A')) & (charMinusLow - 64)) < 0) &&
                                ((long)((0x9000000090000000UL << (int)(charMinusLow = (uint)span[i + 1] - 'B')) & (charMinusLow - 64)) < 0))
                            {
                                base.runtextpos = pos + i;
                                return true;
                            }
                        }
                    }
                     
                    // No match found.
                    NoMatchFound:
                    base.runtextpos = inputSpan.Length;
                    return false;
                }
         
                /// <summary>Determine whether <paramref name="inputSpan"/> at base.runtextpos is a match for the regular expression.</summary>
                /// <param name="inputSpan">The text being scanned by the regular expression.</param>
                /// <returns>true if the regular expression matches at the current position; otherwise, false.</returns>
                private bool TryMatchAtCurrentPosition(ReadOnlySpan<char> inputSpan)
                {
                    int pos = base.runtextpos;
                    int matchStart = pos;
                    ReadOnlySpan<char> slice = inputSpan.Slice(pos);
                     
                    // Match with 2 alternative expressions, atomically.
                    {
                        if (slice.IsEmpty)
                        {
                            return false; // The input didn't match.
                        }
                         
                        switch (slice[0])
                        {
                            case 'A' or 'a':
                                if ((uint)slice.Length < 3 ||
                                    !slice.Slice(1).StartsWith("bc", StringComparison.OrdinalIgnoreCase)) // Match the string "bc" (ordinal case-insensitive)
                                {
                                    return false; // The input didn't match.
                                }
                                 
                                pos += 3;
                                slice = inputSpan.Slice(pos);
                                break;
                                 
                            case 'D' or 'd':
                                if ((uint)slice.Length < 3 ||
                                    !slice.Slice(1).StartsWith("ef", StringComparison.OrdinalIgnoreCase)) // Match the string "ef" (ordinal case-insensitive)
                                {
                                    return false; // The input didn't match.
                                }
                                 
                                pos += 3;
                                slice = inputSpan.Slice(pos);
                                break;
                                 
                            default:
                                return false; // The input didn't match.
                        }
                    }
                     
                    // The input matched.
                    base.runtextpos = pos;
                    base.Capture(0, matchStart, pos);
                    return true;
                }
            }
        }
 
    }
     
    /// <summary>Helper methods used by generated <see cref="Regex"/>-derived implementations.</summary>
    [GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "7.0.8.17405")]
    file static class Utilities
    {
        /// <summary>Default timeout value set in <see cref="AppContext"/>, or <see cref="Regex.InfiniteMatchTimeout"/> if none was set.</summary>
        internal static readonly TimeSpan s_defaultTimeout = AppContext.GetData("REGEX_DEFAULT_MATCH_TIMEOUT") is TimeSpan timeout ? timeout : Regex.InfiniteMatchTimeout;
         
        /// <summary>Whether <see cref="s_defaultTimeout"/> is non-infinite.</summary>
        internal static readonly bool s_hasTimeout = s_defaultTimeout != Timeout.InfiniteTimeSpan;
    }
}

Code and pdf at

https://ignatandrei.github.io/RSCG_Examples/v2/docs/System.Text.Json