TableQuery.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;
using System.Collections.Generic;
using System.Linq.Expressions;

using Deveel.Data.Sql;
using Deveel.Data.Sql.Expressions;

namespace Deveel.Data.Linq {
    class TableQuery {
        private readonly List<ColumnQuery> columnQueries;

        public TableQuery() {
            columnQueries = new List<ColumnQuery>();
        }

        public void Column(string columnName, SqlExpression expression) {
            columnQueries.Add(new ColumnQuery(columnName, expression));
        }

        public void Column(string columnName, Expression expression) {
            // TODO: convert the source Linq Expression to a SQL Expression
            throw new NotImplementedException();
        }

        public IEnumerable Execute(Type elementType, ITable table) {
            var mapping = new TableTypeMapper(elementType);

            var finalTable = table;
            foreach (var columnQuery in columnQueries) {
                finalTable = ExecuteColumnQuery(finalTable, columnQuery);
            }

            mapping.BuildMap(finalTable);

            var listType = typeof (List<>).MakeGenericType(elementType);
            var result = (IList) Activator.CreateInstance(listType);

            foreach (var row in finalTable) {
                var rowNumber = row.RowId.RowNumber;
                var mapped = mapping.Construct(finalTable, rowNumber);
                result.Add(mapped);
            }

            return result;
        }

        private ITable ExecuteColumnQuery(ITable table, ColumnQuery columnQuery) {
            var expression = columnQuery.Expression;
            return table.ExhaustiveSelect(null, expression);
        }
    }
}