Ejemplo n.º 1
0
        public virtual string ToString(ExecContext context)
        {
            Variable var = GetByName("ThisToString");

            if (null != var && var.type is TypeDef_Function)
            {
                TypeDef_Function tdf = (TypeDef_Function)var.type;
                if (null != var.value && tdf.retType.Equals(IntrinsicTypeDefs.STRING) && tdf.argTypes.Count == 0)
                {
                    FunctionValue funcVal = (FunctionValue)var.value;
                    return((string)funcVal.Evaluate(context, new List <object>(), this));
                }
            }

            return("[" + classDef.name + " instance]");
        }
Ejemplo n.º 2
0
        public static void Register(Engine engine)
        {
            //@ class List<T>
            TypeDef_Class ourType = TypeFactory.GetTypeDef_Class("List", new ArgList {
                IntrinsicTypeDefs.TEMPLATE_0
            }, false);
            ClassDef classDef = engine.defaultContext.CreateClass("List", ourType, null, new List <string> {
                "T"
            });

            classDef.childAllocator = () => {
                return(new PebbleList());
            };
            classDef.Initialize();

            //@ List<T> Add(T newValue, ...) or List<T> Push(T newValue, ...)
            //   Adds one or more elements to the end of the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    PebbleList scope = thisScope as PebbleList;
                    if (scope.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "Add: Attempt to modify a list that is being enumerated by a foreach loop.");
                        return(null);
                    }

                    var list        = scope.list;
                    var listType    = (TypeDef_Class)scope.classDef.typeDef;
                    var elementType = listType.genericTypes[0];
                    for (int ii = 0; ii < args.Count; ++ii)
                    {
                        object ret = args[ii];
                        list.Add(new Variable(null, elementType, ret));
                    }

                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    IntrinsicTypeDefs.TEMPLATE_0
                }, eval, true, ourType);
                classDef.AddMemberLiteral("Add", newValue.valType, newValue);
                classDef.AddMemberLiteral("Push", newValue.valType, newValue);
            }

            //@ List<T> Clear()
            //   Removes all elements from the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    PebbleList pebList = thisScope as PebbleList;
                    if (pebList.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "Clear: Attempt to modify a list that is being enumerated by a foreach loop.");
                        return(null);
                    }

                    var list = pebList.list;
                    list.Clear();
                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Clear", newValue.valType, newValue);
            }

            //@ num Count()
            //   Returns the number of elements in the list.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    var list = (thisScope as PebbleList).list;
                    return(System.Convert.ToDouble(list.Count));
                };

                FunctionValue_Host newValue = new FunctionValue_Host(IntrinsicTypeDefs.NUMBER, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Count", newValue.valType, newValue);
            }

            //@ T Get(num index)
            //   Returns the value of the element of the list at the given index.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    double dix = (double)args[0];
                    int    ix  = (int)dix;

                    var list = (thisScope as PebbleList).list;

                    // Bounds checking.
                    if (ix < 0 || ix >= list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "Get: Index " + ix + " out of bounds of array of length " + list.Count + ".");
                        return(null);
                    }

                    return(list[ix].value);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(IntrinsicTypeDefs.TEMPLATE_0, new ArgList {
                    IntrinsicTypeDefs.NUMBER
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Get", newValue.valType, newValue);
            }

            //@ List<T> Insert(num index, T item)
            //   Inserts a new element into the list at the given index. Existing elements at and after the given index are pushed further down the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    PebbleList scope = thisScope as PebbleList;
                    if (scope.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "Insert: Attempt to modify a list that is being enumerated by a foreach loop.");
                        return(null);
                    }

                    var list        = scope.list;
                    var listType    = (TypeDef_Class)scope.classDef.typeDef;
                    var elementType = listType.genericTypes[0];
                    var indexDouble = (double)args[0];
                    var item        = args[1];
                    var index       = Convert.ToInt32(indexDouble);
                    if (index < 0 || index > list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "Insert: array index out of bounds.");
                        return(null);
                    }

                    list.Insert(index, new Variable(null, elementType, item));

                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    IntrinsicTypeDefs.NUMBER, IntrinsicTypeDefs.TEMPLATE_0
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Insert", newValue.valType, newValue);
            }

            //@ T Pop()
            //   Returns the value of the last element of the list and removes it from the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    PebbleList pebList = thisScope as PebbleList;
                    if (pebList.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "Pop: Attempt to remove an element from a list that is being enumerated in a foreach loop.");
                        return(null);
                    }

                    var list = pebList.list;
                    int ix   = list.Count - 1;
                    if (ix < 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "Pop: List is empty.");
                        return(null);
                    }

                    var result = list[ix].value;
                    list.RemoveAt(ix);
                    return(result);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(IntrinsicTypeDefs.TEMPLATE_0, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Pop", newValue.valType, newValue);
            }

            //@ List<T> RemoveAt(num index)
            //   Removes element at the given index, and returns the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    double dix = (double)args[0];
                    int    ix  = (int)dix;

                    PebbleList pebList = thisScope as PebbleList;
                    if (pebList.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "RemoveAt: Attempt to modify a list that is being enumerated by a foreach loop.");
                        return(null);
                    }

                    var list = pebList.list;
                    if (ix < 0 || ix >= list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "RemoveAt: Index " + ix + " out of bounds of array of length " + list.Count + ".");
                        return(null);
                    }

                    list.RemoveAt(ix);
                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    IntrinsicTypeDefs.NUMBER
                }, eval, false, ourType);
                classDef.AddMemberLiteral("RemoveAt", newValue.valType, newValue);
            }

            //@ List<T> RemoveRange(num start, num count)
            //   Removes elements in the given range of indices, and returns the list.
            //   Cannot be used in a foreach loop.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    double dstart = (double)args[0];
                    int    start  = (int)dstart;
                    double dcount = (double)args[1];
                    int    count  = (int)dcount;

                    PebbleList pebList = thisScope as PebbleList;
                    if (pebList.enumeratingCount > 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ForeachModifyingContainer, "RemoveRange: Attempt to modify a list that is being enumerated by a foreach loop.");
                        return(null);
                    }

                    var list = pebList.list;
                    if (start < 0 || start >= list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "RemoveRange: Start " + start + " out of bounds of array of length " + list.Count + ".");
                        return(null);
                    }
                    if (count < 0)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "RemoveRange: Count (" + count + ") cannot be negative.");
                        return(null);
                    }
                    if ((start + count) >= list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "RemoveRange: Count " + count + " exceeds array length (" + list.Count + ").");
                        return(null);
                    }

                    list.RemoveRange(start, count);
                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    IntrinsicTypeDefs.NUMBER, IntrinsicTypeDefs.NUMBER
                }, eval, false, ourType);
                classDef.AddMemberLiteral("RemoveRange", newValue.valType, newValue);
            }

            //@ List<T> Reverse()
            //   Reverses the list and returns it.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    var list = (thisScope as PebbleList).list;
                    list.Reverse();
                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Reverse", newValue.valType, newValue);
            }

            //@ List<T> Set(num index, T newValue)
            //   Changes the value of the element at the given index, and returns the list.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    double dix = (double)args[0];
                    int    ix  = (int)dix;

                    object value = args[1];

                    var list = (thisScope as PebbleList).list;

                    // Bounds checking.
                    if (ix < 0 || ix >= list.Count)
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArrayIndexOutOfBounds, "Set: Index " + ix + " out of bounds of array of length " + list.Count + ".");
                        return(null);
                    }

                    list[ix].value = value;

                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    IntrinsicTypeDefs.NUMBER, IntrinsicTypeDefs.TEMPLATE_0
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Set", newValue.valType, newValue);
            }

            //@ List<T> Shuffle()
            //   Shuffles the list, putting the elements in random order.
            //	 Returns the list.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    var list = (thisScope as PebbleList).list;

                    Random rng = new Random();

                    int n = list.Count;
                    while (n > 1)
                    {
                        --n;
                        int      k     = rng.Next(n + 1);
                        Variable value = list[k];
                        list[k] = list[n];
                        list[n] = value;
                    }

                    return(thisScope);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Shuffle", newValue.valType, newValue);
            }

            //@ List<T> Sort(functype<num(T, T>)> comparator)
            //   Sorts the list using the given comparator function.
            //   The comparator should behave the same as a C# Comparer. The first argument should be earlier in the
            //   list than the second, return a number < 0. If It should be later, return a number > 0. If their order
            //   is irrelevant, return 0.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    var list = (thisScope as PebbleList).list;

                    if (null == args[0])
                    {
                        context.SetRuntimeError(RuntimeErrorType.ArgumentInvalid, "Sort: comparator may not be null.");
                        return(null);
                    }

                    FunctionValue comparator = (FunctionValue)args[0];

                    List <object> argvals = new List <object>();
                    argvals.Add(0);
                    argvals.Add(0);

                    Comparison <Variable> hostComparator = new Comparison <Variable>(
                        (a, b) => {
                        argvals[0] = a.value;
                        argvals[1] = b.value;

                        // Note we use null instead of thisScope here. There is no way the sort function could be a
                        // class member because Sort's signature only takes function's whose type has no class.
                        double result = (double)comparator.Evaluate(context, argvals, null);
                        return(Convert.ToInt32(result));
                    }
                        );

                    list.Sort(hostComparator);
                    return(thisScope);
                };

                TypeDef_Function comparatorType = TypeFactory.GetTypeDef_Function(IntrinsicTypeDefs.NUMBER, new ArgList {
                    IntrinsicTypeDefs.TEMPLATE_0, IntrinsicTypeDefs.TEMPLATE_0
                }, -1, false, null, false, false);

                FunctionValue_Host newValue = new FunctionValue_Host(ourType, new ArgList {
                    comparatorType
                }, eval, false, ourType);
                classDef.AddMemberLiteral("Sort", newValue.valType, newValue);
            }

            //@ string ThisToScript(string prefix)
            //   ThisToScript is used by Serialize. A classes' ThisToScript function should return code which can rebuild the class.
            //   Note that it's only the content of the class, not the "new A" part. ie., it's the code that goes in the defstructor.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    string result = "";
                    string prefix = (string)args[0] + "\t";

                    var list = (thisScope as PebbleList).list;
                    for (int ii = 0; ii < list.Count; ++ii)
                    {
                        result += prefix + "Add(" + CoreLib.ValueToScript(context, list[ii].value, prefix + "\t", false) + ");\n";
                    }

                    return(result);
                };

                FunctionValue_Host newValue = new FunctionValue_Host(IntrinsicTypeDefs.STRING, new ArgList {
                    IntrinsicTypeDefs.STRING
                }, eval, false, ourType);
                classDef.AddMemberLiteral("ThisToScript", newValue.valType, newValue);
            }

            //@ string ToString()
            //   Returns a string representation of at least the first few elements of the list.
            {
                FunctionValue_Host.EvaluateDelegate eval = (context, args, thisScope) => {
                    var    list   = (thisScope as PebbleList).list;
                    string result = "List(" + list.Count + ")[";
                    for (int ii = 0; ii < Math.Min(4, list.Count); ++ii)
                    {
                        if (ii > 0)
                        {
                            result += ", ";
                        }
                        result += CoreLib.ValueToString(context, list[ii].value, true);
                    }
                    if (list.Count > 4)
                    {
                        result += ", ...";
                    }
                    return(result + "]");
                };

                FunctionValue_Host newValue = new FunctionValue_Host(IntrinsicTypeDefs.STRING, new ArgList {
                }, eval, false, ourType);
                classDef.AddMemberLiteral("ThisToString", newValue.valType, newValue);
            }

            classDef.FinalizeClass(engine.defaultContext);

            UnitTests.testFuncDelegates.Add("CoreList", RunTests);
        }
Ejemplo n.º 3
0
        public static string ValueToScript(ExecContext context, object value, string prefix = "", bool topLevel = true)
        {
            string result  = "";
            string postfix = topLevel ? ";" : "";

            if (value is double)
            {
                return(Convert.ToString((double)value) + postfix);
            }
            else if (value is bool)
            {
                return(((bool)value ? "true" : "false") + postfix);
            }
            else if (value is string)
            {
                return("\"" + (string)value + "\"" + postfix);
            }
            else if (value is ClassValue_Enum)                 // is enum
            {
                return(((ClassValue_Enum)value).ToString() + postfix);
            }
            else if (value is ClassValue)
            {
                ClassValue table = value as ClassValue;
                result = "new " + table.classDef.typeDef.ToString() + " {\n";

                // ThisToScript must not be static. It's going to be printing info about a class instance, right?
                MemberRef toStrMem = table.classDef.GetMemberRef(null, "ThisToScript", ClassDef.SEARCH.NORMAL);
                Variable  funcVar  = null;
                if (!toStrMem.isInvalid)
                {
                    funcVar = table.Get(toStrMem) as Variable;
                }
                if (null != funcVar)
                {
                    FunctionValue funcVal = funcVar.value as FunctionValue;
                    result += funcVal.Evaluate(context, new List <object> {
                        prefix
                    }, table) as string;
                }
                else
                {
                    foreach (Variable kvp in table.fieldVars)
                    {
                        if (!(kvp.type is TypeDef_Function) && !kvp.type.IsConst())
                        {
                            result += prefix + "\t" + kvp.name + " = " + ValueToScript(context, kvp.value, prefix + "\t", false);
                            if (!result.EndsWith(";"))
                            {
                                result += ";";
                            }
                            result += "\n";
                        }
                    }
                }
                result += prefix + "}" + postfix;
            }
            else if (null == value)
            {
                result = "null" + postfix;
            }
            return(result);
        }
Ejemplo n.º 4
0
            public bool Write(ExecContext context, PebbleStreamHelper stream, object value)
            {
                Pb.Assert(!(value is Variable));

                if (null != textWriter)
                {
                    string s = CoreLib.ValueToString(context, value, false);
                    textWriter.Write(s);
                    return(true);
                }

                if (null == value)
                {
                    writer.Write("null");
                }
                else if (value is FunctionValue)
                {
                    context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Cannot serialize functions.");
                    return(false);
                }
                else if (value is bool)
                {
                    writer.Write((bool)value);
                }
                else if (value is double)
                {
                    writer.Write((double)value);
                }
                else if (value is string)
                {
                    writer.Write((string)value);
                }
                else if (value is PebbleList)
                {
                    PebbleList plist = value as PebbleList;
                    // - Serialize full type, ie "List<string>".
                    writer.Write(plist.classDef.name);
                    // - Serialize count.
                    writer.Write(plist.list.Count);
                    // - Finally, serialize each object.
                    foreach (Variable listvar in plist.list)
                    {
                        if (!Write(context, stream, listvar.value))
                        {
                            return(false);
                        }
                    }
                }
                else if (value is PebbleDictionary)
                {
                    PebbleDictionary dic = value as PebbleDictionary;
                    // - class name
                    writer.Write(dic.classDef.name);
                    // - count
                    writer.Write((Int32)dic.dictionary.Count);
                    // - each key, value
                    foreach (var kvp in dic.dictionary)
                    {
                        if (!Write(context, stream, kvp.Key))
                        {
                            return(false);
                        }
                        if (!Write(context, stream, kvp.Value.value))
                        {
                            return(false);
                        }
                    }
                }
                else if (value is ClassValue_Enum)
                {
                    ClassValue_Enum enumVal = value as ClassValue_Enum;
                    writer.Write(enumVal.classDef.name);
                    writer.Write(enumVal.GetName());
                }
                else if (value is ClassValue)
                {
                    ClassValue classVal  = value as ClassValue;
                    MemberRef  serMemRef = classVal.classDef.GetMemberRef(null, "Serialize", ClassDef.SEARCH.NORMAL);
                    if (serMemRef.isInvalid)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeInvalidClass, "Class '" + classVal.classDef.name + "' cannot be serialized because it doesn't implement a serialization function.");
                        return(false);
                    }

                    writer.Write(classVal.classDef.name);

                    Variable      serVar  = classVal.Get(serMemRef);
                    FunctionValue serFunc = serVar.value as FunctionValue;
                    object        result  = serFunc.Evaluate(context, new List <object> {
                        stream
                    }, classVal);
                    if (context.IsRuntimeErrorSet())
                    {
                        return(false);
                    }
                    if (result is bool && false == (bool)result)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeFailed, "Serialize function of class '" + classVal.classDef.name + "' returned false.");
                        return(false);
                    }
                }
                else
                {
                    throw new Exception("Internal error: Unexpected type of value in stream Write.");
                }

                return(true);
            }
Ejemplo n.º 5
0
            public bool Read(ExecContext context, PebbleStreamHelper stream, Variable variable)
            {
                if (variable.type.IsConst())
                {
                    context.SetRuntimeError(RuntimeErrorType.SerializeIntoConst, "Cannot serialize into const variables.");
                    return(false);
                }

                if (variable.type.CanStoreValue(context, IntrinsicTypeDefs.BOOL))
                {
                    variable.value = reader.ReadBoolean();
                }
                else if (variable.type == IntrinsicTypeDefs.NUMBER)
                {
                    variable.value = reader.ReadDouble();
                }
                else if (variable.type == IntrinsicTypeDefs.STRING)
                {
                    variable.value = reader.ReadString();
                }
                else if (variable.type.GetName().StartsWith("List<"))
                {
                    string listTypeName = reader.ReadString();
                    if ("null" == listTypeName)
                    {
                        variable.value = null;
                        return(true);
                    }

                    // Is it possible that the specific generic class isn't registered yet.
                    if (!EnsureGenericIsRegistered(context, listTypeName))
                    {
                        return(false);
                    }

                    ClassDef listDef = context.GetClass(listTypeName);
                    if (null == listDef)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Cannot deserialize list type '" + listTypeName + "' because it is unknown.");
                        return(false);
                    }

                    ClassValue listValue = listDef.Allocate(context);
                    PebbleList newlist   = listValue as PebbleList;
                    variable.value = listValue;

                    ITypeDef elementType = listDef.typeDef.genericTypes[0];

                    int count = reader.ReadInt32();
                    for (int ii = 0; ii < count; ++ii)
                    {
                        Variable newelem = new Variable(null, elementType);
                        if (!Read(context, stream, newelem))
                        {
                            return(false);
                        }
                        newlist.list.Add(newelem);
                    }
                }
                else if (variable.type.GetName().StartsWith("Dictionary<"))
                {
                    string listTypeName = reader.ReadString();
                    if ("null" == listTypeName)
                    {
                        variable.value = null;
                        return(true);
                    }

                    // Is it possible that the specific generic class isn't registered yet.
                    if (!EnsureGenericIsRegistered(context, listTypeName))
                    {
                        return(false);
                    }

                    ClassDef listDef = context.GetClass(listTypeName);
                    if (null == listDef)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Cannot deserialize list type '" + listTypeName + "' because it is unknown.");
                        return(false);
                    }

                    ClassValue       listValue = listDef.Allocate(context);
                    PebbleDictionary newlist   = listValue as PebbleDictionary;
                    variable.value = listValue;

                    ITypeDef keyType   = listDef.typeDef.genericTypes[0];
                    ITypeDef valueType = listDef.typeDef.genericTypes[1];

                    int      count      = reader.ReadInt32();
                    Variable tempKeyVar = new Variable("tempKeyVar", keyType);
                    for (int ii = 0; ii < count; ++ii)
                    {
                        if (!Read(context, stream, tempKeyVar))
                        {
                            return(false);
                        }

                        Variable newelem = new Variable(null, valueType);
                        if (!Read(context, stream, newelem))
                        {
                            return(false);
                        }
                        newlist.dictionary.Add(tempKeyVar.value, newelem);
                    }
                }
                else if (variable.type is TypeDef_Enum)
                {
                    string enumName  = reader.ReadString();
                    string valueName = reader.ReadString();

                    // This happens.
                    ITypeDef streamedType = context.GetTypeByName(enumName);
                    if (null == streamedType)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Attempt to load saved enum of unknown type '" + enumName + "'.");
                        return(false);
                    }

                    // I can't get this to happen.
                    if (!(streamedType is TypeDef_Enum))
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Type '" + enumName + "' saved as something other than an enum, but attempted to stream into an enum variable.");
                        return(false);
                    }

                    ClassDef enumClassDef = context.GetClass(enumName);
                    Pb.Assert(null != enumClassDef, "Somehow we got a type for an enum but not the def.");
                    ClassDef_Enum enumDef = enumClassDef as ClassDef_Enum;
                    Pb.Assert(null != enumClassDef, "Registered type is enum but def is classdef.");

                    // This happens.
                    ClassValue_Enum cve = enumDef.enumDef.GetValue(valueName);
                    if (null == cve)
                    {
                        context.SetRuntimeError(RuntimeErrorType.EnumValueNotFound, "Enum '" + enumName + "' does not have saved value '" + valueName + "'.");
                        return(false);
                    }

                    variable.value = cve;
                }
                else if (variable.type is TypeDef_Class)
                {
                    TypeDef_Class varType = variable.type as TypeDef_Class;

                    // Get class name.
                    string streamClassName = reader.ReadString();

                    if ("null" == streamClassName)
                    {
                        variable.value = null;
                        return(true);
                    }

                    ITypeDef streamedType = context.GetTypeByName(streamClassName);
                    if (null == streamedType)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeUnknownType, "Serialized type '" + streamClassName + "' not found.");
                        return(false);
                    }

                    if (!varType.CanStoreValue(context, streamedType))
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeTypeMismatch, "Cannot deserialize a '" + streamClassName + "' into a variable of type '" + varType.GetName() + "'.");
                        return(false);
                    }

                    TypeDef_Class streamedClassType = streamedType as TypeDef_Class;
                    Pb.Assert(null != streamedClassType, "Somehow a streamed type is not a class but *can* be stored in a class type?!");

                    ClassDef streamedClassDef = context.GetClass(streamClassName);
                    Pb.Assert(null != streamedClassDef, "Somehow we got a type for a class but not the def.");
                    MemberRef serMemRef = streamedClassDef.GetMemberRef(null, "Serialize", ClassDef.SEARCH.NORMAL);
                    if (serMemRef.isInvalid)
                    {
                        context.SetRuntimeError(RuntimeErrorType.SerializeInvalidClass, "Serialize function of class '" + streamClassName + "' not found.");
                        return(false);
                    }

                    ClassValue    streamedClassValue = streamedClassDef.Allocate(context);
                    Variable      serFuncVar         = streamedClassValue.Get(serMemRef);
                    FunctionValue serFuncVal         = serFuncVar.value as FunctionValue;
                    serFuncVal.Evaluate(context, new List <object>()
                    {
                        stream
                    }, streamedClassValue);
                    if (context.IsRuntimeErrorSet())
                    {
                        return(false);
                    }

                    variable.value = streamedClassValue;
                }
                else
                {
                    throw new Exception("Internal error: Unexpected type of value in stream Read.");
                }

                return(true);
            }