// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics;
 
namespace System.Reflection.Metadata
{
    public readonly struct Constant
    {
        private readonly MetadataReader _reader;
 
        // Workaround: JIT doesn't generate good code for nested structures, so use RowId.
        private readonly int _rowId;
 
        internal Constant(MetadataReader reader, int rowId)
        {
            Debug.Assert(reader != null);
            Debug.Assert(rowId != 0);
 
            _reader = reader;
            _rowId = rowId;
        }
 
        private ConstantHandle Handle
        {
            get
            {
                return ConstantHandle.FromRowId(_rowId);
            }
        }
 
        /// <summary>
        /// The type of the constant value.
        /// </summary>
        /// <remarks>
        /// Corresponds to Type field of Constant table in ECMA-335 Standard.
        /// </remarks>
        public ConstantTypeCode TypeCode
        {
            get
            {
                return _reader.ConstantTable.GetType(Handle);
            }
        }
 
        /// <summary>
        /// The constant value.
        /// </summary>
        /// <remarks>
        /// Corresponds to Value field of Constant table in ECMA-335 Standard.
        /// </remarks>
        public BlobHandle Value
        {
            get
            {
                return _reader.ConstantTable.GetValue(Handle);
            }
        }
 
        /// <summary>
        /// The parent handle (<see cref="ParameterHandle"/>, <see cref="FieldDefinitionHandle"/>, or <see cref="PropertyDefinitionHandle"/>).
        /// </summary>
        /// <remarks>
        /// Corresponds to Parent field of Constant table in ECMA-335 Standard.
        /// </remarks>
        public EntityHandle Parent
        {
            get
            {
                return _reader.ConstantTable.GetParent(Handle);
            }
        }
    }
}