135 lines
3.7 KiB
C++
135 lines
3.7 KiB
C++
//
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// Created by light on 20-1-8.
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//
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#ifndef MORDEN_C_OUTPUT_CONTAINER_H
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#define MORDEN_C_OUTPUT_CONTAINER_H
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#include <ostream> // std::ostream
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#include <type_traits> // std::false_type/true_type/decay_t/is_same_v
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#include <utility> // std::declval/pair
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// 检测是否是pair
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template <typename T> struct is_pair : std::false_type {};
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template <typename T, typename U>
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struct is_pair<std::pair<T, U>> : std::true_type {};
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template <typename T> inline constexpr bool is_pair_v = is_pair<T>::value;
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// 检测输出函数是否存在
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template <typename T> struct has_output_function {
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template <class U>
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static auto output(U *ptr)
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-> decltype(std::declval<std::ostream &>() << *ptr, std::true_type());
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template <class U> static std::false_type output(...);
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static constexpr bool value = decltype(output<T>(nullptr))::value;
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};
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template <typename T>
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inline constexpr bool has_output_function_v = has_output_function<T>::value;
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enum CHARS {
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ORD, // 其他类型
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CHAR, // char 类型
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STRING // string 类型
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};
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template <typename T> int ischarOrString(T &elem) {
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using std::decay_t;
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using std::is_same_v;
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using element_type = decay_t<decltype(elem)>;
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constexpr bool is_char_v = is_same_v<element_type, char>;
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constexpr bool is_string_v = is_same_v<element_type, char *> ||
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is_same_v<element_type, const char *> ||
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is_same_v<element_type, std::string>;
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if (is_char_v)
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return CHAR;
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else if (is_string_v)
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return STRING;
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else
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return ORD;
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}
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template <typename T> void output(T &elem, int type, std::ostream &os) {
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switch (type) {
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case CHAR:
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os << '\'' << elem << '\'';
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break;
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case STRING:
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os << '\"' << elem << '\"';
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break;
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case ORD:
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os << elem;
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break;
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}
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}
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template <typename T, typename Cont>
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auto output_element(std::ostream &os, const T &element, const Cont &) ->
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typename std::enable_if<is_pair<typename Cont::value_type>::value,
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bool>::type {
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int ftype = ischarOrString(element.first);
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int stype = ischarOrString(element.second);
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output(element.first, ftype, os);
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os << " => ";
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output(element.second, stype, os);
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return true;
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}
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template <typename T, typename Cont>
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auto output_element(std::ostream &os, const T &element, const Cont &) ->
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typename std::enable_if<!is_pair<typename Cont::value_type>::value,
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bool>::type {
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int etype = ischarOrString(element);
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output(element, etype, os);
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return false;
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}
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template <typename T, typename U>
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std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &pr) {
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os << '(' << pr.first << ", " << pr.second << ')';
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return os;
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}
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// template<typename T, typename Cont>
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// auto output_element(std::ostream& os, const T& element,
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// const Cont&, const std::true_type)
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//-> decltype(std::declval<typename Cont::key_type>(), os)
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//{
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// os << element.first << " => " << element.second;
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// return os;
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// }
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//
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// template <typename T, typename Cont>
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// auto output_element(std::ostream& os, const T& element,
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// const Cont&, ...)
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//-> decltype(os)
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//{
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// os << element;
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// return os;
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// }
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// 针对没有输出函数的容器处理
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template <typename T, typename = std::enable_if_t<!has_output_function_v<T>>>
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auto operator<<(std::ostream &os, const T &container)
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-> decltype(container.begin(), container.end(), os) {
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os << "{ ";
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if (!container.empty()) {
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bool on_first_element = true;
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for (auto elem : container) {
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if (!on_first_element) {
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os << ", ";
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} else {
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on_first_element = false;
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}
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output_element(os, elem, container);
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}
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}
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os << " }";
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return os;
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}
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#endif // MORDEN_C_OUTPUT_CONTAINER_H
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