CreateViewStatement.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

using Deveel.Data.Serialization;
using Deveel.Data.Sql.Expressions;
using Deveel.Data.Sql.Query;
using Deveel.Data.Sql.Tables;
using Deveel.Data.Sql.Views;

namespace Deveel.Data.Sql.Statements {
    public sealed class CreateViewStatement : SqlStatement, IPreparableStatement {
        public CreateViewStatement(string viewName, SqlQueryExpression queryExpression) 
            : this(viewName, null, queryExpression) {
        }

        public CreateViewStatement(string viewName, IEnumerable<string> columnNames, SqlQueryExpression queryExpression) {
            if (viewName == null)
                throw new ArgumentNullException("viewName");
            if (queryExpression == null)
                throw new ArgumentNullException("queryExpression");

            ViewName = viewName;
            ColumnNames = columnNames;
            QueryExpression = queryExpression;
        }

        public string ViewName { get; private set; }

        public IEnumerable<string> ColumnNames { get; private set; }

        public SqlQueryExpression QueryExpression { get; private set; }

        public bool ReplaceIfExists { get; set; }

        IStatement IPreparableStatement.Prepare(IRequest context) {
            var viewName = context.Query.ResolveTableName(ViewName);

            var queryFrom = QueryExpressionFrom.Create(context, QueryExpression);
            var queryPlan = context.Query.Context.QueryPlanner().PlanQuery(new QueryInfo(context, QueryExpression));

            var colList = ColumnNames == null ? new string[0] : ColumnNames.ToArray();

            // Wrap the result around a SubsetNode to alias the columns in the
            // table correctly for this view.
            int sz = colList.Length;
            var originalNames = queryFrom.GetResolvedColumns();
            var newColumnNames = new ObjectName[originalNames.Length];

            if (sz > 0) {
                if (sz != originalNames.Length)
                    throw new InvalidOperationException("Column list is not the same size as the columns selected.");

                for (int i = 0; i < sz; ++i) {
                    var colName = colList[i];
                    newColumnNames[i] = new ObjectName(viewName, colName);
                }
            } else {
                sz = originalNames.Length;
                for (int i = 0; i < sz; ++i) {
                    newColumnNames[i] = new ObjectName(viewName, originalNames[i].Name);
                }
            }

            // Check there are no repeat column names in the table.
            for (int i = 0; i < sz; ++i) {
                var columnName = newColumnNames[i];
                for (int n = i + 1; n < sz; ++n) {
                    if (newColumnNames[n].Equals(columnName))
                        throw new InvalidOperationException(String.Format("Duplicate column name '{0}' in view. A view may not contain duplicate column names.", columnName));
                }
            }

            // Wrap the plan around a SubsetNode plan
            queryPlan = new SubsetNode(queryPlan, originalNames, newColumnNames);

            return new Prepared(viewName, QueryExpression, queryPlan, ReplaceIfExists);
        }

        #region Prepared

        [Serializable]
        class Prepared : SqlStatement {
            internal Prepared(ObjectName viewName, SqlQueryExpression queryExpression, IQueryPlanNode queryPlan, bool replaceIfExists) {
                ViewName = viewName;
                QueryPlan = queryPlan;
                ReplaceIfExists = replaceIfExists;
                QueryExpression = queryExpression;
            }

            private Prepared(ObjectData data) {
                ViewName = data.GetValue<ObjectName>("Name");
                QueryPlan = data.GetValue<IQueryPlanNode>("QueryPlan");
                ReplaceIfExists = data.GetBoolean("ReplaceIfExists");
                QueryExpression = data.GetValue<SqlQueryExpression>("QueryExpression");
            }

            public ObjectName ViewName { get; private set; }

            public IQueryPlanNode QueryPlan { get; private set; }

            public bool ReplaceIfExists { get; set; }

            public SqlQueryExpression QueryExpression { get; private set; }

            protected override void GetData(SerializeData data) {
                data.SetValue("Name", ViewName);
                data.SetValue("QueryPlan", QueryPlan);
                data.SetValue("QueryExpression", QueryExpression);
                data.SetValue("ReplaceIfExists", ReplaceIfExists);
            }

            protected override void ExecuteStatement(ExecutionContext context) {
                // We have to execute the plan to get the TableInfo that represents the
                // result of the view execution.
                var table = QueryPlan.Evaluate(context.Request);
                var tableInfo = table.TableInfo.Alias(ViewName);

                var viewInfo = new ViewInfo(tableInfo, QueryExpression, QueryPlan);
                context.Request.Query.DefineView(viewInfo, ReplaceIfExists);
            }
        }

        #endregion

        #region PreparedSerializer

        //internal class PreparedSerializer : ObjectBinarySerializer<Prepared> {
        //  public override void Serialize(Prepared obj, BinaryWriter writer) {
        //      ObjectName.Serialize(obj.ViewName, writer);

        //      var queryPlanTypeName = obj.QueryPlan.GetType().FullName;
        //      writer.Write(queryPlanTypeName);

        //      QueryPlanSerializers.Serialize(obj.QueryPlan, writer);
        //      SqlExpression.Serialize(obj.QueryExpression, writer);
        //      writer.Write(obj.ReplaceIfExists);
        //  }

        //  public override Prepared Deserialize(BinaryReader reader) {
        //      var viewName = ObjectName.Deserialize(reader);

        //      var queryPlanTypeName = reader.ReadString();
        //      var queryPlanType = Type.GetType(queryPlanTypeName, true);
        //      var queryPlan = QueryPlanSerializers.Deserialize(queryPlanType, reader);

        //      var queryExpression = SqlExpression.Deserialize(reader) as SqlQueryExpression;
        //      var replaceIfExists = reader.ReadBoolean();

        //      return new Prepared(viewName, queryExpression, queryPlan, replaceIfExists);
        //  }
        //}

        #endregion
    }
}