SqlStatement.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.Linq;

using Deveel.Data.Serialization;
using Deveel.Data.Sql.Compile;
using Deveel.Data.Sql.Parser;
using Deveel.Data.Sql.Expressions;
using Deveel.Data.Sql.Tables;

namespace Deveel.Data.Sql.Statements {
    [Serializable]
    public abstract class SqlStatement : IStatement, ISerializable {
        protected SqlStatement() {
            
        }

        protected SqlStatement(ObjectData data) {
            SourceQuery = data.GetValue<SqlQuery>("SourceQuery");
            IsFromQuery = data.GetBoolean("IsFromQuery");
        }

        public SqlQuery SourceQuery { get; set; }

        public bool IsFromQuery { get; private set; }

        void IExecutable.Execute(ExecutionContext context) {
            ExecuteStatement(context);
        }

        protected virtual void ExecuteStatement(ExecutionContext context) {
            throw new NotSupportedException(String.Format("The statement '{0}' does not support execution", GetType().Name));
        }

        internal void SetSource(SqlQuery query) {
            SourceQuery = query;
            IsFromQuery = true;
        }

        void ISerializable.GetData(SerializeData data) {
            data.SetValue("SourceQuery", SourceQuery);
            data.SetValue("IsFromQuery", IsFromQuery);

            GetData(data);
        }

        protected virtual void GetData(SerializeData data) {
            
        }

        public ITable Execute(IRequest context) {
            return PrepareAndExecute(null, context);
        }

        private ITable PrepareAndExecute(IExpressionPreparer preparer, IRequest context) {
            IExecutable prepared;

            try {
                prepared = this.Prepare(preparer, context);
            } catch (Exception ex) {
                throw new InvalidOperationException("Unable to prepare the statement for execution.", ex);
            }

            if (prepared == null)
                throw new InvalidOperationException();

            var exeContext = new ExecutionContext(context);
            prepared.Execute(exeContext);
            if (!exeContext.HasResult)
                return FunctionTable.ResultTable(context, 0);

            return exeContext.Result;
        }

        public static IEnumerable<SqlStatement> Parse(string sqlSource) {
            return Parse(null, sqlSource);
        }

        public static IEnumerable<SqlStatement> Parse(IContext context, string sqlSource) {
            return Parse(context, new SqlQuery(sqlSource));
        }

        private static readonly ISqlCompiler DefaultCompiler = new SqlDefaultCompiler();

        

        public static IEnumerable<SqlStatement> Parse(IContext context, SqlQuery query) {
            if (query == null)
                throw new ArgumentNullException("query");

            var compiler = DefaultCompiler;

            if (context != null) {
                compiler = context.ResolveService<ISqlCompiler>();
            }

            try {
                var compileContext = new SqlCompileContext(context, query.Text);
                var result = compiler.Compile(compileContext);
                if (result.HasErrors)
                    throw new SqlParseException();

                var statements = result.Statements.Cast<SqlStatement>();

                foreach (var statement in statements) {
                    if (statement != null)
                        statement.SetSource(query);
                }

                return statements;
            } catch (SqlParseException) {
                throw;
            } catch (Exception ex) {
                throw new SqlParseException("The input string cannot be parsed into SQL Statements", ex);
            }
        }
    }
}