IndexExpressionFingerprint.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System.Diagnostics.CodeAnalysis;
using System.Linq.Expressions;
using System.Reflection;

#pragma warning disable 659 // overrides AddToHashCodeCombiner instead

namespace System.Web.Mvc.ExpressionUtil
{
    // IndexExpression fingerprint class
    // Represents certain forms of array access or indexer property access

    [SuppressMessage("Microsoft.Usage", "CA2218:OverrideGetHashCodeOnOverridingEquals", Justification = "Overrides AddToHashCodeCombiner() instead.")]
    internal sealed class IndexExpressionFingerprint : ExpressionFingerprint
    {
        public IndexExpressionFingerprint(ExpressionType nodeType, Type type, PropertyInfo indexer)
            : base(nodeType, type)
        {
            // Other properties on IndexExpression (like the argument count) are simply derived
            // from Type and Indexer, so they're not necessary for inclusion in the fingerprint.

            Indexer = indexer;
        }

        // http://msdn.microsoft.com/en-us/library/system.linq.expressions.indexexpression.indexer.aspx
        public PropertyInfo Indexer { get; private set; }

        public override bool Equals(object obj)
        {
            IndexExpressionFingerprint other = obj as IndexExpressionFingerprint;
            return (other != null)
                   && Equals(this.Indexer, other.Indexer)
                   && this.Equals(other);
        }

        internal override void AddToHashCodeCombiner(HashCodeCombiner combiner)
        {
            combiner.AddObject(Indexer);
            base.AddToHashCodeCombiner(combiner);
        }
    }
}