InitializeLocalInstruction.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 InitializeLocalInstruction : LocalAccessInstruction
{
    internal sealed class Reference : InitializeLocalInstruction, IBoxableInstruction
    {
        public override string InstructionName => "InitRef";
 
        internal Reference(int index)
            : base(index)
        {
        }
 
        public override int Run(InterpretedFrame frame)
        {
            frame.Data[_index] = null;
            return 1;
        }
 
        public Instruction BoxIfIndexMatches(int index)
        {
            if (index != _index)
            {
                return null;
            }
            return InstructionList.InitImmutableRefBox(index);
        }
    }
 
    internal sealed class ImmutableValue : InitializeLocalInstruction, IBoxableInstruction
    {
        private readonly object _defaultValue;
 
        public override string InstructionName => "InitImmutableValue";
 
        internal ImmutableValue(int index, object defaultValue)
            : base(index)
        {
            _defaultValue = defaultValue;
        }
 
        public override int Run(InterpretedFrame frame)
        {
            frame.Data[_index] = _defaultValue;
            return 1;
        }
 
        public Instruction BoxIfIndexMatches(int index)
        {
            if (index != _index)
            {
                return null;
            }
            return new ImmutableBox(index, _defaultValue);
        }
    }
 
    internal sealed class ImmutableBox : InitializeLocalInstruction
    {
        private readonly object _defaultValue;
 
        public override string InstructionName => "InitImmutableBox";
 
        internal ImmutableBox(int index, object defaultValue)
            : base(index)
        {
            _defaultValue = defaultValue;
        }
 
        public override int Run(InterpretedFrame frame)
        {
            frame.Data[_index] = new StrongBox<object>(_defaultValue);
            return 1;
        }
    }
 
    internal sealed class ImmutableRefBox : InitializeLocalInstruction
    {
        public override string InstructionName => "InitImmutableBox";
 
        internal ImmutableRefBox(int index)
            : base(index)
        {
        }
 
        public override int Run(InterpretedFrame frame)
        {
            frame.Data[_index] = new StrongBox<object>();
            return 1;
        }
    }
 
    internal sealed class ParameterBox : InitializeLocalInstruction
    {
        public override string InstructionName => "InitParameterBox";
 
        public ParameterBox(int index)
            : base(index)
        {
        }
 
        public override int Run(InterpretedFrame frame)
        {
            frame.Data[_index] = new StrongBox<object>(frame.Data[_index]);
            return 1;
        }
    }
 
    internal sealed class Parameter : InitializeLocalInstruction, IBoxableInstruction
    {
        public override string InstructionName => "InitParameter";
 
        internal Parameter(int index)
            : base(index)
        {
        }
 
        public override int Run(InterpretedFrame frame)
        {
            return 1;
        }
 
        public Instruction BoxIfIndexMatches(int index)
        {
            if (index == _index)
            {
                return InstructionList.ParameterBox(index);
            }
            return null;
        }
    }
 
    internal sealed class MutableValue : InitializeLocalInstruction, IBoxableInstruction
    {
        private readonly Type _type;
 
        public override string InstructionName => "InitMutableValue";
 
        internal MutableValue(int index, Type type)
            : base(index)
        {
            _type = type;
        }
 
        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2077:UnrecognizedReflectionPattern", Justification = "_type is a ValueType. You can always get an uninitialized ValueType.")]
        public override int Run(InterpretedFrame frame)
        {
            try
            {
                frame.Data[_index] = (_type.IsNullableType() ? Activator.CreateInstance(_type) : RuntimeHelpers.GetUninitializedObject(_type));
            }
            catch (TargetInvocationException exception)
            {
                ExceptionHelpers.UnwrapAndRethrow(exception);
                throw ContractUtils.Unreachable;
            }
            return 1;
        }
 
        public Instruction BoxIfIndexMatches(int index)
        {
            if (index != _index)
            {
                return null;
            }
            return new MutableBox(index, _type);
        }
    }
 
    internal sealed class MutableBox : InitializeLocalInstruction
    {
        private readonly Type _type;
 
        public override string InstructionName => "InitMutableBox";
 
        internal MutableBox(int index, Type type)
            : base(index)
        {
            _type = type;
        }
 
        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2077:UnrecognizedReflectionPattern", Justification = "_type is a ValueType. You can always get an uninitialized ValueType.")]
        public override int Run(InterpretedFrame frame)
        {
            object value;
            try
            {
                value = (_type.IsNullableType() ? Activator.CreateInstance(_type) : RuntimeHelpers.GetUninitializedObject(_type));
            }
            catch (TargetInvocationException exception)
            {
                ExceptionHelpers.UnwrapAndRethrow(exception);
                throw ContractUtils.Unreachable;
            }
            frame.Data[_index] = new StrongBox<object>(value);
            return 1;
        }
    }
 
    internal InitializeLocalInstruction(int index)
        : base(index)
    {
    }
}