//---------------------------------------------------------------------
// <copyright file="NamespaceImport.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner  Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
 
namespace System.Data.Common.EntitySql.AST
{
    /// <summary>
    /// Represents an ast node for namespace import (using nsABC;)
    /// </summary>
    internal sealed class NamespaceImport : Node
    {
        private readonly Identifier _namespaceAlias;
        private readonly Node _namespaceName;
 
        /// <summary>
        /// Initializes a single name import.
        /// </summary>
        internal NamespaceImport(Identifier idenitifier)
        {
            _namespaceName = idenitifier;
        }
 
        /// <summary>
        /// Initializes a single name import.
        /// </summary>
        internal NamespaceImport(DotExpr dorExpr)
        {
            _namespaceName = dorExpr;
        }
 
        /// <summary>
        /// Initializes aliased import.
        /// </summary>
        internal NamespaceImport(BuiltInExpr bltInExpr)
        {
            _namespaceAlias = null;
 
            Identifier aliasId = bltInExpr.Arg1 as Identifier;
            if (aliasId == null)
            {
                throw EntityUtil.EntitySqlError(bltInExpr.Arg1.ErrCtx, System.Data.Entity.Strings.InvalidNamespaceAlias);
            }
 
            _namespaceAlias = aliasId;
            _namespaceName = bltInExpr.Arg2;
        }
 
        /// <summary>
        /// Returns ns alias id if exists.
        /// </summary>
        internal Identifier Alias
        {
            get { return _namespaceAlias; }
        }
 
        /// <summary>
        /// Returns namespace name.
        /// </summary>
        internal Node NamespaceName
        {
            get { return _namespaceName; }
        }
    }
}