1 /* 2 * Copyright (c) 2024 Huawei Device Co., Ltd. 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 16 #ifndef META_INTERFACE_PROPERTY_MODIFIER_H 17 #define META_INTERFACE_PROPERTY_MODIFIER_H 18 19 #include <meta/base/interface_macros.h> 20 #include <meta/base/namespace.h> 21 #include <meta/base/types.h> 22 #include <meta/interface/intf_function.h> 23 #include <meta/interface/property/intf_property.h> 24 25 META_BEGIN_NAMESPACE() 26 27 /// Result the modifier evaluation functions return 28 enum EvaluationResult : uint8_t { 29 EVAL_CONTINUE = 0, /// Continue evaluation of the stack 30 EVAL_ERROR = 1, /// Error happened 31 EVAL_RETURN = 2, /// Stop stack evaluation and return value 32 EVAL_VALUE_CHANGED = 4, /// This modifier changed the value 33 }; 34 35 inline EvaluationResult operator|(EvaluationResult l, EvaluationResult r) 36 { 37 return EvaluationResult(uint8_t(l) | uint8_t(r)); 38 } 39 40 META_REGISTER_INTERFACE(IModifier, "4a6991b7-c410-4663-99d2-4ff00eb9a9e0") 41 42 /** 43 * @brief Modifier for property to allow to alter the property's behaviour on evaluation 44 * 45 * Modifiers can be added to property. The ProcessOnGet is called when GetValue is called 46 * for the property. The ProcessOnSet is called when SetValue is called for the property. 47 * In both cases the stack is evaluated and the modifiers are called in the order they are 48 * set for the property (for get from first to last and for set from last to first). 49 * The evaluation functions can alter the value being get/set and/or control the further 50 * evaluation process by terminating it, short circuiting it or simply continuing. 51 */ 52 class IModifier : public CORE_NS::IInterface { 53 META_INTERFACE(CORE_NS::IInterface, IModifier) 54 public: 55 /** 56 * @brief Evaluation function for GetValue calls 57 * @param value The top most value in property stack (possibly after other modifiers have altered it). 58 * @return Evaluation result which decides the action for further modifier evaluation 59 */ 60 virtual EvaluationResult ProcessOnGet(IAny& value) = 0; 61 /** 62 * @brief Evaluation function for SetValue calls 63 * @param value The value being set for the property 64 * @return Evaluation result which decides the action for further modifier evaluation and setting the value 65 */ 66 virtual EvaluationResult ProcessOnSet(IAny& value, const IAny& current) = 0; 67 /// Check if this modifier is compatible with given type id 68 virtual bool IsCompatible(const TypeId& id) const = 0; 69 }; 70 71 META_INTERFACE_TYPE(META_NS::IModifier) 72 73 META_END_NAMESPACE() 74 75 #endif 76