Configuration.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;

using Deveel.Data;

namespace Deveel.Data.Configuration {
    public class Configuration : IConfiguration {
        private readonly bool isRoot;
        private readonly Dictionary<string, object> values;

        private Configuration(bool isRoot) {
            Parent = null;
            this.isRoot = isRoot;
            values = new Dictionary<string, object>();
        }

        public Configuration(IConfiguration parent, IConfigSource source)
            : this(parent == null) {
            Parent = parent;
            Source = source;

            if (source != null)
                this.Load(source);
        }

        public Configuration(IConfigSource source)
            : this(null, source) {
        }

        public Configuration()
            : this(true) {
        }

        public Configuration(IConfiguration parent)
            : this(parent, null) {
        }

        public IConfigSource Source { get; set; }

        public IConfiguration Parent { get; set; }

        public IEnumerable<string> GetKeys(ConfigurationLevel level) {
            var returnKeys = new Dictionary<string, string>();
            if (!isRoot && Parent != null && level == ConfigurationLevel.Deep) {
                var configKeys = Parent.GetKeys(level);
                foreach (var pair in configKeys) {
                    returnKeys[pair] = pair;
                }
            }

            foreach (var configKey in values.Keys) {
                returnKeys[configKey] = configKey;
            }

            return returnKeys.Values.AsEnumerable();
        }

        public IEnumerator<KeyValuePair<string, object>> GetEnumerator() {
            var keys = GetKeys(ConfigurationLevel.Deep);
            return keys.Select(key => new KeyValuePair<string, object>(key, GetValue(key))).GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator() {
            return GetEnumerator();
        }


        public void SetValue(string key, object value) {
            if (String.IsNullOrEmpty(key))
                throw new ArgumentNullException("key");

            if (value == null) {
                values.Remove(key);
            } else {
                values[key] = value;
            }
        }

        public object GetValue(string key) {
            if (String.IsNullOrEmpty(key))
                throw new ArgumentNullException("key");

            object value;
            if (values.TryGetValue(key, out value))
                return value;

            if (!isRoot && Parent != null && 
                ((value = Parent.GetValue(key)) != null))
                return value;

            return null;
        }
    }
}