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using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
using System.Text;
using System.Text.RegularExpressions;
namespace com.bodurov
{
public static class DataSourceCreator
{
private static readonly Regex PropertNameRegex =
new Regex(@"^[A-Za-z]+[A-Za-z0-9_]*$", RegexOptions.Singleline);
private static readonly Dictionary<string, Type> _typeBySigniture =
new Dictionary<string, Type>();
public static IEnumerable ToDataSource(this IEnumerable<IDictionary> list)
{
IDictionary firstDict = null;
bool hasData = false;
foreach (IDictionary currentDict in list)
{
hasData = true;
firstDict = currentDict;
break;
}
if (!hasData)
{
return new object[] { };
}
if (firstDict == null)
{
throw new ArgumentException("IDictionary entry cannot be null");
}
string typeSignature = GetTypeSignature(firstDict, list);
Type objectType = GetTypeByTypeSignature(typeSignature);
if (objectType == null)
{
TypeBuilder tb = GetTypeBuilder(typeSignature);
ConstructorBuilder constructor =
tb.DefineDefaultConstructor(
MethodAttributes.Public |
MethodAttributes.SpecialName |
MethodAttributes.RTSpecialName);
foreach (DictionaryEntry pair in firstDict)
{
if (PropertNameRegex.IsMatch(Convert.ToString(pair.Key), 0))
{
CreateProperty(tb,
Convert.ToString(pair.Key),
GetValueType(pair.Value, list, pair.Key));
}
else
{
throw new ArgumentException(
@"Each key of IDictionary must be
alphanumeric and start with character.");
}
}
objectType = tb.CreateType();
_typeBySigniture.Add(typeSignature, objectType);
}
return GenerateEnumerable(objectType, list, firstDict);
}
private static Type GetTypeByTypeSignature(string typeSigniture)
{
Type type;
return _typeBySigniture.TryGetValue(typeSigniture, out type) ? type : null;
}
private static Type GetValueType(object value, IEnumerable<IDictionary> list, object key)
{
if(value == null)
{
foreach (var dictionary in list)
{
if(dictionary.Contains(key))
{
value = dictionary[key];
if(value != null) break;
}
}
}
return (value == null) ? typeof(object) : value.GetType();
}
private static string GetTypeSignature(IDictionary firstDict, IEnumerable<IDictionary> list)
{
var sb = new StringBuilder();
foreach (DictionaryEntry pair in firstDict)
{
sb.AppendFormat("_{0}_{1}", pair.Key, GetValueType(pair.Value, list, pair.Key));
}
return sb.ToString().GetHashCode().ToString().Replace("-", "Minus");
}
private static IEnumerable GenerateEnumerable(
Type objectType, IEnumerable<IDictionary> list, IDictionary firstDict)
{
var listType = typeof(List<>).MakeGenericType(new[] { objectType });
var listOfCustom = Activator.CreateInstance(listType);
foreach (var currentDict in list)
{
if (currentDict == null)
{
throw new ArgumentException("IDictionary entry cannot be null");
}
var row = Activator.CreateInstance(objectType);
foreach (DictionaryEntry pair in firstDict)
{
if (currentDict.Contains(pair.Key))
{
PropertyInfo property =
objectType.GetProperty(Convert.ToString(pair.Key));
var value = currentDict[pair.Key];
if (value != null &&
value.GetType() != property.PropertyType &&
!property.PropertyType.IsGenericType){
try
{
value = Convert.ChangeType(
currentDict[pair.Key],
property.PropertyType,
null);
}catch{}
}
property.SetValue(row, value, null);
}
}
listType.GetMethod("Add").Invoke(listOfCustom, new[] { row });
}
return listOfCustom as IEnumerable;
}
private static TypeBuilder GetTypeBuilder(string typeSigniture)
{
AssemblyName an = new AssemblyName("TempAssembly" + typeSigniture);
AssemblyBuilder assemblyBuilder =
AppDomain.CurrentDomain.DefineDynamicAssembly(
an, AssemblyBuilderAccess.Run);
ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("MainModule");
TypeBuilder tb = moduleBuilder.DefineType("TempType" + typeSigniture
, TypeAttributes.Public |
TypeAttributes.Class |
TypeAttributes.AutoClass |
TypeAttributes.AnsiClass |
TypeAttributes.BeforeFieldInit |
TypeAttributes.AutoLayout
, typeof(object));
return tb;
}
private static void CreateProperty(
TypeBuilder tb, string propertyName, Type propertyType)
{
if(propertyType.IsValueType && !propertyType.IsGenericType)
{
propertyType = typeof(Nullable<>).MakeGenericType(new[] { propertyType });
}
FieldBuilder fieldBuilder = tb.DefineField("_" + propertyName,
propertyType,
FieldAttributes.Private);
PropertyBuilder propertyBuilder =
tb.DefineProperty(
propertyName, PropertyAttributes.HasDefault, propertyType, null);
MethodBuilder getPropMthdBldr =
tb.DefineMethod("get_" + propertyName,
MethodAttributes.Public |
MethodAttributes.SpecialName |
MethodAttributes.HideBySig,
propertyType, Type.EmptyTypes);
ILGenerator getIL = getPropMthdBldr.GetILGenerator();
getIL.Emit(OpCodes.Ldarg_0);
getIL.Emit(OpCodes.Ldfld, fieldBuilder);
getIL.Emit(OpCodes.Ret);
MethodBuilder setPropMthdBldr =
tb.DefineMethod("set_" + propertyName,
MethodAttributes.Public |
MethodAttributes.SpecialName |
MethodAttributes.HideBySig,
null, new Type[] { propertyType });
ILGenerator setIL = setPropMthdBldr.GetILGenerator();
setIL.Emit(OpCodes.Ldarg_0);
setIL.Emit(OpCodes.Ldarg_1);
setIL.Emit(OpCodes.Stfld, fieldBuilder);
setIL.Emit(OpCodes.Ret);
propertyBuilder.SetGetMethod(getPropMthdBldr);
propertyBuilder.SetSetMethod(setPropMthdBldr);
}
}
}