37 lines
1.0 KiB
C++
37 lines
1.0 KiB
C++
#ifndef MEMBER_CHECKER_H
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#define MEMBER_CHECKER_H
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#define DEFINE_MEMBER_CHECKER(member) \
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template<typename T, typename V = bool> \
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struct has_ ## member : false_type { }; \
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\
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template<typename T> \
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struct has_ ## member<T, \
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typename enable_if< \
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!is_same<decltype(declval<T>().member), void>::value, \
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bool \
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>::type \
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> : true_type { };
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#define HAS_MEMBER(C, member) \
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has_ ## member<C>::value
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// first getter if the member veriable is present, so we return its value
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// second getter, when the member is not present, so we return empty value, e.g., empty string
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#define DEFINE_MEMBER_GETTER(member, ret_value) \
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template<typename T> \
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typename enable_if<HAS_MEMBER(T, member), ret_value>::type \
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get_ ## member (T t){ \
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return t.member; \
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} \
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\
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template<typename T> \
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typename enable_if<!HAS_MEMBER(T, member), ret_value>::type \
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get_ ## member (T t){ \
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return ret_value(); \
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}
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#endif // MEMBER_CHECKER_H
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