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

        internal LocalBuilder GetTempLocal(Type type)
        {
            LocalBuilder localTmp;
            if (!_tmpLocals.TryGetValue(type, out localTmp))
            {
                localTmp = DeclareLocal(type, "_tmp" + _tmpLocals.Count);
                _tmpLocals.Add(type, localTmp);
            }
            return localTmp;
        }

        void WriteEnumMethod(EnumMapping mapping) {
            MethodBuilder get_TableName = null;
            if (mapping.IsFlags)
                WriteHashtable(mapping, mapping.TypeDesc.Name, out get_TableName);

            string methodName = (string)MethodNames[mapping];
            string fullTypeName = mapping.TypeDesc.CSharpName;
            List<Type> argTypes = new List<Type>();
            List<string> argNames = new List<string>();
            Type returnType;
            Type underlyingType;

            returnType = mapping.TypeDesc.Type;
            underlyingType = Enum.GetUnderlyingType(returnType);
            argTypes.Add(typeof(string));
            argNames.Add("s");
            ilg = new CodeGenerator(this.typeBuilder);
            ilg.BeginMethod(
                returnType,
                GetMethodBuilder(methodName),
                argTypes.ToArray(),
                argNames.ToArray(),
                CodeGenerator.PrivateMethodAttributes);

            ConstantMapping[] constants = mapping.Constants;
            if (mapping.IsFlags) {
                {
                    MethodInfo XmlSerializationReader_ToEnum = typeof(XmlSerializationReader).GetMethod(
                        "ToEnum",
                        CodeGenerator.StaticBindingFlags,
                        null,
                        new Type[] { typeof(String), typeof(Hashtable), typeof(String) },
                        null
                        );
                    ilg.Ldarg("s");
                    ilg.Ldarg(0);
                    Debug.Assert(get_TableName != null);
                    ilg.Call(get_TableName);
                    ilg.Ldstr(fullTypeName);
                    ilg.Call(XmlSerializationReader_ToEnum);
                    // XmlSerializationReader_ToEnum return long!
                    if (underlyingType != typeof(long)) {
                        ilg.ConvertValue(typeof(long), underlyingType);
                    }
                    ilg.Stloc(ilg.ReturnLocal);
                    ilg.Br(ilg.ReturnLabel);
                }
            }
            else {
                List<Label> caseLabels = new List<Label>();
                List<object> retValues = new List<object>();
                Label defaultLabel = ilg.DefineLabel();
                Label endSwitchLabel = ilg.DefineLabel();
                // This local is necessary; otherwise, it becomes if/else
                LocalBuilder localTmp = ilg.GetTempLocal(typeof(string));
                ilg.Ldarg("s");
                ilg.Stloc(localTmp);
                ilg.Ldloc(localTmp);
                ilg.Brfalse(defaultLabel);
                Hashtable cases = new Hashtable();
                for (int i = 0; i < constants.Length; i++) {
                    ConstantMapping c = constants[i];

                    CodeIdentifier.CheckValidIdentifier(c.Name);
                    if (cases[c.XmlName] == null) {
                        cases[c.XmlName] = c.XmlName;
                        Label caseLabel = ilg.DefineLabel();
                        ilg.Ldloc(localTmp);
                        ilg.Ldstr(c.XmlName);
                        MethodInfo String_op_Equality = typeof(string).GetMethod(
                            "op_Equality",
                            CodeGenerator.StaticBindingFlags,
                            null,
                            new Type[] { typeof(string), typeof(string) },
                            null
                            );
                        ilg.Call(String_op_Equality);
                        ilg.Brtrue(caseLabel);
                        caseLabels.Add(caseLabel);
                        retValues.Add(Enum.ToObject(mapping.TypeDesc.Type, c.Value));
                    }
                }

                ilg.Br(defaultLabel);
                // Case bodies
                for (int i = 0; i < caseLabels.Count; i++) {
                    ilg.MarkLabel(caseLabels[i]);
                    ilg.Ldc(retValues[i]);
                    ilg.Stloc(ilg.ReturnLocal);
                    ilg.Br(ilg.ReturnLabel);
                }
                MethodInfo XmlSerializationReader_CreateUnknownConstantException = typeof(XmlSerializationReader).GetMethod(
                    "CreateUnknownConstantException",
                    CodeGenerator.InstanceBindingFlags,
                    null,
                    new Type[] { typeof(string), typeof(Type) },
                    null
                    );
                // Default body
                ilg.MarkLabel(defaultLabel);
                ilg.Ldarg(0);
                ilg.Ldarg("s");
                // typeof(..)
                ilg.Ldc(mapping.TypeDesc.Type);
                ilg.Call(XmlSerializationReader_CreateUnknownConstantException);
                ilg.Throw();
                // End switch
                ilg.MarkLabel(endSwitchLabel);
            }

            ilg.MarkLabel(ilg.ReturnLabel);
            ilg.Ldloc(ilg.ReturnLocal);
            ilg.EndMethod();
        }