// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;

namespace Microsoft.CodeAnalysis
{
    [Flags]
    internal enum ValueUsageInfo
    {
        /// <summary>
        /// Represents default value indicating no usage.
        /// </summary>
        None = 0x0,

        /// <summary>
        /// Represents a value read.
        /// For example, reading the value of a local/field/parameter.
        /// </summary>
        Read = 0x1,

        /// <summary>
        /// Represents a value write.
        /// For example, assigning a value to a local/field/parameter.
        /// </summary>
        Write = 0x2,

        /// <summary>
        /// Represents a reference being taken for the symbol.
        /// For example, passing an argument to an "in", "ref" or "out" parameter.
        /// </summary>
        Reference = 0x4,

        /// <summary>
        /// Represents a name-only reference that neither reads nor writes the underlying value.
        /// For example, 'nameof(x)' or reference to a symbol 'x' in a documentation comment
        /// does not read or write the underlying value stored in 'x'.
        /// </summary>
        Name = 0x8,

        /// <summary>
        /// Represents a value read and/or write.
        /// For example, an increment or compound assignment operation.
        /// </summary>
        ReadWrite = Read | Write,

        /// <summary>
        /// Represents a readable reference being taken to the value.
        /// For example, passing an argument to an "in" or "ref readonly" parameter.
        /// </summary>
        ReadableReference = Read | Reference,

        /// <summary>
        /// Represents a readable reference being taken to the value.
        /// For example, passing an argument to an "out" parameter.
        /// </summary>
        WritableReference = Write | Reference,

        /// <summary>
        /// Represents a value read or write.
        /// For example, passing an argument to a "ref" parameter.
        /// </summary>
        ReadableWritableReference = Read | Write | Reference
    }

    internal static class ValueUsageInfoExtensions
    {
        public static bool IsReadFrom(this ValueUsageInfo valueUsageInfo)
            => (valueUsageInfo & ValueUsageInfo.Read) != 0;

        public static bool IsWrittenTo(this ValueUsageInfo valueUsageInfo)
            => (valueUsageInfo & ValueUsageInfo.Write) != 0;

        public static bool IsNameOnly(this ValueUsageInfo valueUsageInfo)
            => (valueUsageInfo & ValueUsageInfo.Name) != 0;

        public static bool IsReference(this ValueUsageInfo valueUsageInfo)
            => (valueUsageInfo & ValueUsageInfo.Reference) != 0;
    }
}
