System.Xml.Serialization.CodeGenerator.WhileBegin C# (CSharp) Method

        internal void WhileBegin()
        {
            WhileState whileState = new WhileState(this);
            Br(whileState.CondLabel);
            MarkLabel(whileState.StartLabel);
            _whileStack.Push(whileState);
        }

        internal void ILGenForCreateInstance(CodeGenerator ilg, Type type, Type cast, bool nonPublic)
        {
            // Special case DBNull
            if (type == Globals.TypeOfDBNull)
            {
                FieldInfo DBNull_Value = Globals.TypeOfDBNull.GetField("Value", CodeGenerator.StaticBindingFlags);
                ilg.LoadMember(DBNull_Value);
                return;
            }

            // Special case XElement
            // codegen the same as 'internal XElement : this("default") { }'
            if (type.FullName == "System.Xml.Linq.XElement")
            {
                Type xName = type.GetTypeInfo().Assembly.GetType("System.Xml.Linq.XName");
                if (xName != null)
                {
                    MethodInfo XName_op_Implicit = xName.GetMethod(
                        "op_Implicit",
                        CodeGenerator.StaticBindingFlags,
                        new Type[] { typeof(String) }
                        );
                    ConstructorInfo XElement_ctor = type.GetConstructor(
                        CodeGenerator.InstanceBindingFlags,
                        new Type[] { xName }
                        );
                    if (XName_op_Implicit != null && XElement_ctor != null)
                    {
                        ilg.Ldstr("default");
                        ilg.Call(XName_op_Implicit);
                        ilg.New(XElement_ctor);
                        return;
                    }
                }
            }

            Label labelReturn = ilg.DefineLabel();
            Label labelEndIf = ilg.DefineLabel();

            // TypeInfo typeInfo = type.GetTypeInfo();
            // typeInfo not declared explicitly
            ilg.Ldc(type);
            MethodInfo getTypeInfoMehod = typeof(IntrospectionExtensions).GetMethod(
                  "GetTypeInfo",
                  CodeGenerator.StaticBindingFlags,
                  new[] { typeof(Type) }
                  );
            ilg.Call(getTypeInfoMehod);

            // IEnumerator<ConstructorInfo> e = typeInfo.DeclaredConstructors.GetEnumerator();
            LocalBuilder enumerator = ilg.DeclareLocal(typeof(IEnumerator<>).MakeGenericType(typeof(ConstructorInfo)), "e");
            MethodInfo getDeclaredConstructors = typeof(TypeInfo).GetMethod("get_DeclaredConstructors");
            MethodInfo getEnumerator = typeof(IEnumerable<>).MakeGenericType(typeof(ConstructorInfo)).GetMethod("GetEnumerator");
            ilg.Call(getDeclaredConstructors);
            ilg.Call(getEnumerator);
            ilg.Stloc(enumerator);

            ilg.WhileBegin();
            // ConstructorInfo constructorInfo = e.Current();
            MethodInfo enumeratorCurrent = typeof(IEnumerator).GetMethod("get_Current");
            ilg.Ldloc(enumerator);
            ilg.Call(enumeratorCurrent);
            LocalBuilder constructorInfo = ilg.DeclareLocal(typeof(ConstructorInfo), "constructorInfo");
            ilg.Stloc(constructorInfo);

            // if (!constructorInfo.IsStatic && constructorInfo.GetParameters.Length() == 0)
            ilg.Ldloc(constructorInfo);
            MethodInfo constructorIsStatic = typeof(ConstructorInfo).GetMethod("get_IsStatic");
            ilg.Call(constructorIsStatic);
            ilg.Brtrue(labelEndIf);
            ilg.Ldloc(constructorInfo);
            MethodInfo constructorGetParameters = typeof(ConstructorInfo).GetMethod("GetParameters");
            ilg.Call(constructorGetParameters);
            ilg.Ldlen();
            ilg.Ldc(0);
            ilg.Cne();
            ilg.Brtrue(labelEndIf);

            // constructorInfo.Invoke(null);
            MethodInfo constructorInvoke = typeof(ConstructorInfo).GetMethod("Invoke", new Type[] { typeof(object[]) });
            ilg.Ldloc(constructorInfo);
            ilg.Load(null);
            ilg.Call(constructorInvoke);
            ilg.Br(labelReturn);

            ilg.MarkLabel(labelEndIf);
            ilg.WhileBeginCondition(); // while (e.MoveNext())
            MethodInfo IEnumeratorMoveNext = typeof(IEnumerator).GetMethod(
                "MoveNext",
                CodeGenerator.InstanceBindingFlags,
                Array.Empty<Type>());
            ilg.Ldloc(enumerator);
            ilg.Call(IEnumeratorMoveNext);
            ilg.WhileEndCondition();
            ilg.WhileEnd();

            MethodInfo Activator_CreateInstance = typeof(Activator).GetMethod(
                  "CreateInstance",
                  CodeGenerator.StaticBindingFlags,
                  new Type[] { typeof(Type) }
                  );
            ilg.Ldc(type);
            ilg.Call(Activator_CreateInstance);
            ilg.MarkLabel(labelReturn);
            if (cast != null)
                ilg.ConvertValue(Activator_CreateInstance.ReturnType, cast);
        }