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

namespace Deveel.Data.Routines {
    public sealed class InvokeContext : IDisposable {
        private DataObject[] evaluatedArgs;
        private Dictionary<string, DataObject> output; 

        internal InvokeContext(Invoke invoke, IRoutine routine, IVariableResolver resolver, IGroupResolver group, IRequest request) {
            if (invoke == null)
                throw new ArgumentNullException("invoke");
            if (routine == null)
                throw new ArgumentNullException("routine");

            Request = request;
            GroupResolver = group;
            VariableResolver = resolver;
            Invoke = invoke;
            Routine = routine;
        }

        ~InvokeContext() {
            Dispose(false);
        }

        public Invoke Invoke { get; private set; }

        public IRoutine Routine { get; private set; }

        public RoutineType RoutineType {
            get { return Routine.Type; }
        }

        public SqlExpression[] Arguments {
            get { return Invoke.Arguments; }
        }

        public IVariableResolver VariableResolver { get; private set; }

        public IGroupResolver GroupResolver { get; private set; }

        public IRequest Request { get; private set; }

        public DataObject[] EvaluatedArguments {
            get {
                if (evaluatedArgs == null) {
                    evaluatedArgs = new DataObject[Arguments.Length];
                    for (int i = 0; i < Arguments.Length; i++) {
                        evaluatedArgs[i] = Arguments[i].EvaluateToConstant(Request, VariableResolver);
                    }
                }

                return evaluatedArgs;
            }
        }

        public int ArgumentCount {
            get { return Arguments == null ? 0 : Arguments.Length; }
        }

        public bool TryGetArgument(string argName, out SqlExpression value) {
            var parameter = Routine.RoutineInfo.Parameters.FirstOrDefault(x => x.Name.Equals(argName, StringComparison.Ordinal));
            if (parameter == null) {
                value = null;
                return false;
            }

            var offset = parameter.Offset;
            if (parameter.IsUnbounded) {
                // TODO: Copy all arguments starting at the given offset and make an Array
                var tuple = SqlExpression.Tuple(new SqlExpression[0]);
                value = tuple;
            } else {
                value = Invoke.Arguments[offset];
            }

            return true;
        }

        public bool TryGetArgument(string argName, out DataObject value) {
            SqlExpression exp;
            if (!TryGetArgument(argName, out exp)) {
                value = DataObject.Null();
                return false;
            }

            value = exp.EvaluateToConstant(Request, VariableResolver);
            return true;
        }

        public bool HasArgument(string argName) {
            throw new NotImplementedException();
        }

        public InvokeResult Result(DataObject value) {
            if (Routine.Type != RoutineType.Function)
                throw new InvalidOperationException("The routine is not a function.");

            return new InvokeResult(this, value);
        }

        public InvokeResult Result() {
            if (Routine.Type != RoutineType.Procedure)
                throw new InvalidOperationException("The routine is not a procedure: a return value is required.");

            return new InvokeResult(this);
        }

        private RoutineParameter GetParameter(string name) {
            return Routine.RoutineInfo.Parameters.FirstOrDefault(x => x.Name.Equals(name, StringComparison.Ordinal));
        }

        public void SetOutput(string argName, DataObject value) {
            var parameter = GetParameter(argName);
            if (parameter == null)
                throw new InvalidOperationException(String.Format("Routine {0} has none parameter named '{1}'.", Routine.FullName, argName));
            if (!parameter.IsOutput)
                throw new InvalidOperationException();

            if (!parameter.IsNullable &&
                value.IsNull)
                throw new ArgumentException();

            if (!parameter.IsUnbounded)
                throw new ArgumentException();

            if (!parameter.Type.IsComparable(value.Type))
                throw new ArgumentException();

            if (output == null)
                output = new Dictionary<string, DataObject>();

            output[argName] = value;
        }

        private void Dispose(bool disposing) {
            Routine = null;
            Invoke = null;
            evaluatedArgs = null;
            output = null;
        }

        public void Dispose() {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
    }
}