private static Expression NextFactory(Type type, RecursionGuard recursion)
{
if (recursion.TypeInRecursionStack(type))
{
// End the recursion.
return(Expression.Constant(null, type));
}
if (TryGetTypeFactory(type, out var tf))
{
return(tf);
}
if (TryGetDictionaryFactory(type, recursion, out var df))
{
return(df);
}
if (TryGetListFactory(type, recursion, out var lf))
{
return(lf);
}
if (TryGetCollectionFactory(type, recursion, out var af))
{
return(af);
}
var nextRecursion = new RecursionGuard(recursion, type);
var defaultContructor = type.GetConstructor(Type.EmptyTypes);
if (defaultContructor != null)
{
var properties = type.GetProperties().Where(x => x.CanWrite).ToArray();
if (properties.Any())
{
// We have an empty constructor and some public properties lets just call that and set... them.
var propertyBindings = properties
.Select(p => (MemberBinding)Expression.Bind(p, NextFactory(p.PropertyType, nextRecursion)))
.ToArray();
return(Expression.MemberInit(Expression.New(type), propertyBindings));
}
}
var(constructor, parameters) = type.GetConstructors()
.Select(c => (c, parameters: c.GetParameters()))
.OrderByDescending(x => x.parameters.Length)
.FirstOrDefault();
if (constructor == null)
{
throw new ArgumentException("No public constructors: " + type, nameof(type));
}
// Use constructor... it's probably there for a reason.
var parameterExpressions = parameters.Select(p => NextFactory(p.ParameterType, nextRecursion)).ToArray();
return(Expression.New(constructor, parameterExpressions));
}
public RecursionGuard(RecursionGuard previous, Type type)
{
var previousStackLength = previous._typeStack.Length;
_typeStack = new Type[previousStackLength + 1];
Array.Copy(previous._typeStack, _typeStack, previousStackLength);
_typeStack[previousStackLength] = type;
}
private static bool TryGetCollectionFactory(Type type, RecursionGuard recursion, out Expression f)
{
var elementType = GetCollectionElementType(type);
if (elementType == null)
{
f = null;
return(false);
}
var nextRecursion = new RecursionGuard(recursion, type);
var elementTypeFactory = NextFactory(elementType, nextRecursion);
var size = Rng.Int(MinimumCollectionSize, MaximumCollectionSize);
f = Expression.NewArrayInit(elementType, Enumerable.Repeat(elementTypeFactory, size));
return(true);
}
private static bool TryGetListFactory(Type type, RecursionGuard recursion, out Expression f)
{
var elementType = IsGenericType(type, typeof(List <>)) ? type.GenericTypeArguments.FirstOrDefault() : null;
if (elementType == null)
{
f = null;
return(false);
}
var nextRecursion = new RecursionGuard(recursion, type);
var entryFactory = NextFactory(elementType, nextRecursion);
var addMethod = type.GetMethod("Add");
var size = Rng.Int(MinimumCollectionSize, MaximumCollectionSize);
var entries = Enumerable.Range(0, size).Select(_ => Expression.ElementInit(addMethod, entryFactory)).ToArray();
f = Expression.ListInit(Expression.New(type), entries);
return(true);
}
private static bool TryGetDictionaryFactory(Type type, RecursionGuard recursion, out Expression f)
{
var(key, value) = GetDictionaryElementTypes(type);
if (key == null || value == null)
{
f = null;
return(false);
}
var nextRecursion = new RecursionGuard(recursion, type);
var keyFactory = NextFactory(key, nextRecursion);
var valueFactory = NextFactory(value, nextRecursion);
var dictionaryType = typeof(Dictionary <,>).MakeGenericType(key, value);
var addMethod = dictionaryType.GetMethod("Add");
var size = Rng.Int(MinimumCollectionSize, MaximumCollectionSize);
var entries = Enumerable.Range(0, size).Select(_ => Expression.ElementInit(addMethod, keyFactory, valueFactory)).ToArray();
f = Expression.ListInit(Expression.New(dictionaryType), entries);
return(true);
}