// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
using System;
using ILLink.Shared.DataFlow;
 
namespace ILLink.RoslynAnalyzer.DataFlow
{
    public class LocalDataFlowState<TValue, TContext, TValueLattice, TContextLattice>
        : IDataFlowState<LocalStateAndContext<TValue, TContext>, LocalStateAndContextLattice<TValue, TContext, TValueLattice, TContextLattice>>
        where TValue : struct, IEquatable<TValue>
        where TContext : struct, IEquatable<TContext>
        where TValueLattice : ILattice<TValue>
        where TContextLattice : ILattice<TContext>
    {
        private LocalStateAndContext<TValue, TContext> current;
        public LocalStateAndContext<TValue, TContext> Current
        {
            get => current;
            set => current = value;
        }
 
        public Box<LocalStateAndContext<TValue, TContext>>? Exception { get; set; }
 
        public LocalStateAndContextLattice<TValue, TContext, TValueLattice, TContextLattice> Lattice { get; init; }
 
        public void Set(LocalKey key, TValue value)
        {
            current.LocalState.Set(key, value);
            if (Exception != null)
                // TODO: optimize this to not meet the whole value, but just modify one value without copying.
                Exception.Value = Lattice.Meet(Exception.Value, current);
        }
 
        public TValue Get(LocalKey key) => current.LocalState.Get(key);
    }
}