NullableMethodCallInstruction.cs

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using System.Diagnostics.CodeAnalysis;
using System.Dynamic.Utils;
using System.Reflection;
using System.Runtime.CompilerServices;
 
namespace System.Linq.Expressions.Interpreter;
 
internal abstract class NullableMethodCallInstruction : Instruction
{
    private sealed class HasValue : NullableMethodCallInstruction
    {
        public override int Run(InterpretedFrame frame)
        {
            object obj = frame.Pop();
            frame.Push(obj != null);
            return 1;
        }
    }
 
    private sealed class GetValue : NullableMethodCallInstruction
    {
        public override int Run(InterpretedFrame frame)
        {
            if (frame.Peek() == null)
            {
                return ((int?)null).Value;
            }
            return 1;
        }
    }
 
    private sealed class GetValueOrDefault : NullableMethodCallInstruction
    {
        private readonly Type _defaultValueType;
 
        public GetValueOrDefault(MethodInfo mi)
        {
            _defaultValueType = mi.ReturnType;
        }
 
        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2077:UnrecognizedReflectionPattern", Justification = "_defaultValueType is a ValueType. You can always get an uninitialized ValueType.")]
        public override int Run(InterpretedFrame frame)
        {
            if (frame.Peek() == null)
            {
                frame.Pop();
                frame.Push(RuntimeHelpers.GetUninitializedObject(_defaultValueType));
            }
            return 1;
        }
    }
 
    private sealed class GetValueOrDefault1 : NullableMethodCallInstruction
    {
        public override int ConsumedStack => 2;
 
        public override int Run(InterpretedFrame frame)
        {
            object obj = frame.Pop();
            object obj2 = frame.Pop();
            frame.Push(obj2 ?? obj);
            return 1;
        }
    }
 
    private sealed class EqualsClass : NullableMethodCallInstruction
    {
        public override int ConsumedStack => 2;
 
        public override int Run(InterpretedFrame frame)
        {
            object obj = frame.Pop();
            object obj2 = frame.Pop();
            if (obj2 == null)
            {
                frame.Push(obj == null);
            }
            else if (obj == null)
            {
                frame.Push(Utils.BoxedFalse);
            }
            else
            {
                frame.Push(obj2.Equals(obj));
            }
            return 1;
        }
    }
 
    private sealed class ToStringClass : NullableMethodCallInstruction
    {
        public override int Run(InterpretedFrame frame)
        {
            object obj = frame.Pop();
            frame.Push((obj == null) ? "" : obj.ToString());
            return 1;
        }
    }
 
    private sealed class GetHashCodeClass : NullableMethodCallInstruction
    {
        public override int Run(InterpretedFrame frame)
        {
            frame.Push(frame.Pop()?.GetHashCode() ?? 0);
            return 1;
        }
    }
 
    private static NullableMethodCallInstruction s_hasValue;
 
    private static NullableMethodCallInstruction s_value;
 
    private static NullableMethodCallInstruction s_equals;
 
    private static NullableMethodCallInstruction s_getHashCode;
 
    private static NullableMethodCallInstruction s_getValueOrDefault1;
 
    private static NullableMethodCallInstruction s_toString;
 
    public override int ConsumedStack => 1;
 
    public override int ProducedStack => 1;
 
    public override string InstructionName => "NullableMethod";
 
    private NullableMethodCallInstruction()
    {
    }
 
    public static Instruction Create(string method, int argCount, MethodInfo mi)
    {
        switch (method)
        {
        case "get_HasValue":
            return s_hasValue ?? (s_hasValue = new HasValue());
        case "get_Value":
            return s_value ?? (s_value = new GetValue());
        case "Equals":
            return s_equals ?? (s_equals = new EqualsClass());
        case "GetHashCode":
            return s_getHashCode ?? (s_getHashCode = new GetHashCodeClass());
        case "GetValueOrDefault":
            if (argCount == 0)
            {
                return new GetValueOrDefault(mi);
            }
            return s_getValueOrDefault1 ?? (s_getValueOrDefault1 = new GetValueOrDefault1());
        case "ToString":
            return s_toString ?? (s_toString = new ToStringClass());
        default:
            throw ContractUtils.Unreachable;
        }
    }
 
    public static Instruction CreateGetValue()
    {
        return s_value ?? (s_value = new GetValue());
    }
}