/// <summary>
/// Verifies that the given type has constructors to migrate from all ancestor types.
/// </summary>
private static void VerifyConstructors(VersionedType type)
{
ConstructorInfo[] publicConstructors = type.ModelType.GetDeclaredConstructors();
for (int i = 0; i < type.Ancestors.Length; ++i)
{
Type requiredConstructorType = type.Ancestors[i].ModelType;
bool found = false;
for (int j = 0; j < publicConstructors.Length; ++j)
{
var parameters = publicConstructors[j].GetParameters();
if (parameters.Length == 1 && parameters[0].ParameterType == requiredConstructorType)
{
found = true;
break;
}
}
if (found == false)
{
throw new MissingVersionConstructorException(type.ModelType, requiredConstructorType);
}
}
}
/// <summary>
/// Verifies that the given version graph contains only unique versions.
/// </summary>
private static void VerifyUniqueVersionStrings(VersionedType type)
{
// simple tree traversal
var found = new Dictionary <string, Type>();
var remaining = new Queue <VersionedType>();
remaining.Enqueue(type);
while (remaining.Count > 0)
{
VersionedType item = remaining.Dequeue();
// Verify we do not already have the version string. Take into account that we're not just
// comparing the same model twice, since we can have a valid import graph that has the same
// model multiple times.
if (found.ContainsKey(item.VersionString) && found[item.VersionString] != item.ModelType)
{
throw new DuplicateVersionNameException(found[item.VersionString], item.ModelType, item.VersionString);
}
found[item.VersionString] = item.ModelType;
// scan the ancestors as well
foreach (var ancestor in item.Ancestors)
{
remaining.Enqueue(ancestor);
}
}
}
public static Result GetVersionImportPath(string currentVersion, VersionedType targetVersion, out List <VersionedType> path)
{
path = new List <VersionedType>();
if (GetVersionImportPathRecursive(path, currentVersion, targetVersion) == false)
{
return(Result.Fail("There is no migration path from \"" + currentVersion + "\" to \"" + targetVersion.VersionString + "\""));
}
path.Add(targetVersion);
return(Result.Success);
}
public static Option <VersionedType> GetVersionedType(Type type)
{
Option <VersionedType> optionalVersionedType;
if (_cache.TryGetValue(type, out optionalVersionedType) == false)
{
var attr = PortableReflection.GetAttribute <ObjectAttribute>(type);
if (attr != null)
{
if (string.IsNullOrEmpty(attr.VersionString) == false || attr.PreviousModels != null)
{
// Version string must be provided
if (attr.PreviousModels != null && string.IsNullOrEmpty(attr.VersionString))
{
throw new Exception("Object attribute on " + type + " contains a PreviousModels specifier - it must also include a VersionString modifier");
}
// Map the ancestor types into versioned types
VersionedType[] ancestors = new VersionedType[attr.PreviousModels != null ? attr.PreviousModels.Length : 0];
for (int i = 0; i < ancestors.Length; ++i)
{
Option <VersionedType> ancestorType = GetVersionedType(attr.PreviousModels[i]);
if (ancestorType.IsEmpty)
{
throw new Exception("Unable to create versioned type for ancestor " + ancestorType + "; please add an [Object(VersionString=\"...\")] attribute");
}
ancestors[i] = ancestorType.Value;
}
// construct the actual versioned type instance
VersionedType versionedType = new VersionedType {
Ancestors = ancestors,
VersionString = attr.VersionString,
ModelType = type
};
// finally, verify that the versioned type passes some sanity checks
VerifyUniqueVersionStrings(versionedType);
VerifyConstructors(versionedType);
optionalVersionedType = Option.Just(versionedType);
}
}
_cache[type] = optionalVersionedType;
}
return(optionalVersionedType);
}
private static bool GetVersionImportPathRecursive(List <VersionedType> path, string currentVersion, VersionedType current)
{
for (int i = 0; i < current.Ancestors.Length; ++i)
{
VersionedType ancestor = current.Ancestors[i];
if (ancestor.VersionString == currentVersion ||
GetVersionImportPathRecursive(path, currentVersion, ancestor))
{
path.Add(ancestor);
return(true);
}
}
return(false);
}
