VariableManager.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 Deveel.Data.Types;

namespace Deveel.Data.Sql.Variables {
    public sealed class VariableManager : IVariableManager {
        private Dictionary<string, Variable> variables;
 
        public VariableManager(IVariableScope scope) {
            Scope = scope;

            variables = new Dictionary<string, Variable>();
        }

        public IVariableScope Scope { get; private set; }

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

        private void Dispose(bool disposing) {
            if (disposing) {
                if (variables != null)
                    variables.Clear();
            }

            variables = null;
        }

        public Variable DefineVariable(VariableInfo variableInfo) {
            if (variableInfo == null)
                throw new ArgumentNullException("variableInfo");

            if (variables.ContainsKey(variableInfo.VariableName))
                throw new ArgumentException();

            var variable = new Variable(variableInfo);
            variables[variableInfo.VariableName] = variable;
            return variable;
        }

        public bool VariableExists(string name) {
            return variables.ContainsKey(name);
        }

        public Variable GetVariable(string name) {
            Variable variable;
            if (!variables.TryGetValue(name, out variable))
                return null;

            return variable;
        }

        public bool DropVariable(string name) {
            return variables.Remove(name);
        }

        DataObject IVariableResolver.Resolve(ObjectName variableName) {
            Variable variable;
            if (!variables.TryGetValue(variableName.Name, out variable))
                return null;

            return variable.Value;
        }

        SqlType IVariableResolver.ReturnType(ObjectName variableName) {
            Variable variable;
            if (!variables.TryGetValue(variableName.Name, out variable))
                return null;

            return variable.Type;
        }
    }
}