#region License
/* 
 * Copyright (C) 1999-2024 John Källén.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#endregion

using Reko.Core;
using Reko.Core.Expressions;

namespace Reko.Evaluation
{
    public partial class ExpressionSimplifier
    {
        public virtual (Expression, bool) VisitIdentifier(Identifier id)
        {
            var e = idConst.Match(id, this.ctx, unifier, listener);
            if (e is not null)
            {
                return (e, true);
            }
            e = idProcConstRule.Match(id, ctx);
            if (e is not null)
            {
                return (e, true);
            }
            // jkl: Copy propagation causes real problems when used during trashed register analysis.
            // If needed in other passes, it should be an option for expression e
            e = IdCopyPropagation(id, ctx);
            if (e is not null)
            {
                return (e, true);
            }
            e = idBinIdc.Match(id, ctx);
            if (e is not null)
            {
                return (e, true);
            }
            return (id, false);
        }

        private static Expression? IdCopyPropagation(Identifier id, EvaluationContext ctx)
        {
            var idOld = id;
            if (ctx.GetValue(id) is not Identifier idNew || idNew == idOld)
                return null;

            return idNew;
        }

    }
}
