using System; 
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel.Composition;
using System.ComponentModel.Composition.Hosting;
using System.ComponentModel.Composition.Primitives;
using System.Linq;
using System.Text;
 
public class ConfigurationExportProvider : ExportProvider
 {
     private ILookup<string, object> _valueLookup; 
 
     public ConfigurationExportProvider(ILookup<string,object> valueLookup)
     {
         _valueLookup = valueLookup;
     }
 
     protected override IEnumerable<Export> GetExportsCore(ImportDefinition importDefinition, AtomicComposition composition)
     {
         var contractName = importDefinition.ContractName;
         if (contractName == null)
             return Enumerable.Empty<Export>(); 
 
         if (!_valueLookup.Contains(contractName))
             return Enumerable.Empty<Export>();
 
         return new Collection<Export>(){
             new Export(contractName, () => {return _valueLookup[contractName].FirstOrDefault();})
         };
     }
 }
 
//IValueLookup implementation for talking to a dictionary
 
    public class ValueLookup : ILookup<string,object> 
    {
        public ValueLookup(IDictionary<string,object> configValues)
        {
            _configValues = configValues;
        }
 
        private IDictionary<string,object> _configValues;
        
        public object GetValue(string key)
        {
            return _configValues[key];
        }
 
        public bool ContainsKey(string key)
        {
            return _configValues.ContainsKey(key);
        }
 
        public IEnumerator<IGrouping<string, object>> GetEnumerator()
        {
            var groupBy = _configValues.GroupBy(item => item.Key, item => item.Value).AsEnumerable();
            return groupBy.GetEnumerator();
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
 
        public bool Contains(string key)
        {
            return _configValues.ContainsKey(key);
        }
 
        public int Count
        {
            get { return _configValues.Count; }
        }
 
        public IEnumerable<object> this[string key]
        {
            get
            {
                return new List<object> {_configValues[key]};
            }
        }
    }