mirror of https://github.com/CrowCpp/Crow.git
332 lines
14 KiB
C++
332 lines
14 KiB
C++
#pragma once
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#include "crow/http_request.h"
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#include "crow/http_response.h"
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#include "crow/utility.h"
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#include <tuple>
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#include <type_traits>
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#include <iostream>
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#include <utility>
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namespace crow // NOTE: Already documented in "crow/app.h"
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{
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/// Local middleware should extend ILocalMiddleware
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struct ILocalMiddleware
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{
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using call_global = std::false_type;
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};
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namespace detail
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{
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template<typename MW>
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struct check_before_handle_arity_3_const
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{
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template<typename T, void (T::*)(request&, response&, typename MW::context&) const = &T::before_handle>
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struct get
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{};
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};
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template<typename MW>
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struct check_before_handle_arity_3
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{
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template<typename T, void (T::*)(request&, response&, typename MW::context&) = &T::before_handle>
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struct get
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{};
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};
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template<typename MW>
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struct check_after_handle_arity_3_const
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{
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template<typename T, void (T::*)(request&, response&, typename MW::context&) const = &T::after_handle>
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struct get
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{};
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};
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template<typename MW>
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struct check_after_handle_arity_3
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{
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template<typename T, void (T::*)(request&, response&, typename MW::context&) = &T::after_handle>
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struct get
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{};
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};
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template<typename MW>
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struct check_global_call_false
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{
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template<typename T, typename std::enable_if<T::call_global::value == false, bool>::type = true>
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struct get
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{};
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};
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template<typename T>
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struct is_before_handle_arity_3_impl
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{
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template<typename C>
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static std::true_type f(typename check_before_handle_arity_3_const<T>::template get<C>*);
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template<typename C>
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static std::true_type f(typename check_before_handle_arity_3<T>::template get<C>*);
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template<typename C>
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static std::false_type f(...);
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public:
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static const bool value = decltype(f<T>(nullptr))::value;
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};
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template<typename T>
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struct is_after_handle_arity_3_impl
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{
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template<typename C>
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static std::true_type f(typename check_after_handle_arity_3_const<T>::template get<C>*);
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template<typename C>
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static std::true_type f(typename check_after_handle_arity_3<T>::template get<C>*);
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template<typename C>
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static std::false_type f(...);
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public:
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static constexpr bool value = decltype(f<T>(nullptr))::value;
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};
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template<typename MW>
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struct is_middleware_global
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{
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template<typename C>
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static std::false_type f(typename check_global_call_false<MW>::template get<C>*);
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template<typename C>
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static std::true_type f(...);
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static const bool value = decltype(f<MW>(nullptr))::value;
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};
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template<typename MW, typename Context, typename ParentContext>
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typename std::enable_if<!is_before_handle_arity_3_impl<MW>::value>::type
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before_handler_call(MW& mw, request& req, response& res, Context& ctx, ParentContext& /*parent_ctx*/)
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{
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mw.before_handle(req, res, ctx.template get<MW>(), ctx);
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}
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template<typename MW, typename Context, typename ParentContext>
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typename std::enable_if<is_before_handle_arity_3_impl<MW>::value>::type
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before_handler_call(MW& mw, request& req, response& res, Context& ctx, ParentContext& /*parent_ctx*/)
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{
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mw.before_handle(req, res, ctx.template get<MW>());
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}
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template<typename MW, typename Context, typename ParentContext>
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typename std::enable_if<!is_after_handle_arity_3_impl<MW>::value>::type
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after_handler_call(MW& mw, request& req, response& res, Context& ctx, ParentContext& /*parent_ctx*/)
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{
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mw.after_handle(req, res, ctx.template get<MW>(), ctx);
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}
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template<typename MW, typename Context, typename ParentContext>
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typename std::enable_if<is_after_handle_arity_3_impl<MW>::value>::type
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after_handler_call(MW& mw, request& req, response& res, Context& ctx, ParentContext& /*parent_ctx*/)
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{
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mw.after_handle(req, res, ctx.template get<MW>());
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}
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template<typename CallCriteria,
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int N, typename Context, typename Container>
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typename std::enable_if<(N < std::tuple_size<typename std::remove_reference<Container>::type>::value), bool>::type
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middleware_call_helper(const CallCriteria& cc, Container& middlewares, request& req, response& res, Context& ctx)
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{
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using CurrentMW = typename std::tuple_element<N, typename std::remove_reference<Container>::type>::type;
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if (!cc.template enabled<CurrentMW>(N))
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{
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return middleware_call_helper<CallCriteria, N + 1, Context, Container>(cc, middlewares, req, res, ctx);
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}
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using parent_context_t = typename Context::template partial<N - 1>;
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before_handler_call<CurrentMW, Context, parent_context_t>(std::get<N>(middlewares), req, res, ctx, static_cast<parent_context_t&>(ctx));
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if (res.is_completed())
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{
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after_handler_call<CurrentMW, Context, parent_context_t>(std::get<N>(middlewares), req, res, ctx, static_cast<parent_context_t&>(ctx));
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return true;
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}
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if (middleware_call_helper<CallCriteria, N + 1, Context, Container>(cc, middlewares, req, res, ctx))
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{
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after_handler_call<CurrentMW, Context, parent_context_t>(std::get<N>(middlewares), req, res, ctx, static_cast<parent_context_t&>(ctx));
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return true;
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}
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return false;
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}
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template<typename CallCriteria, int N, typename Context, typename Container>
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typename std::enable_if<(N >= std::tuple_size<typename std::remove_reference<Container>::type>::value), bool>::type
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middleware_call_helper(const CallCriteria& /*cc*/, Container& /*middlewares*/, request& /*req*/, response& /*res*/, Context& /*ctx*/)
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{
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return false;
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}
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template<typename CallCriteria, int N, typename Context, typename Container>
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typename std::enable_if<(N < 0)>::type
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after_handlers_call_helper(const CallCriteria& /*cc*/, Container& /*middlewares*/, Context& /*context*/, request& /*req*/, response& /*res*/)
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{
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}
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template<typename CallCriteria, int N, typename Context, typename Container>
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typename std::enable_if<(N == 0)>::type after_handlers_call_helper(const CallCriteria& cc, Container& middlewares, Context& ctx, request& req, response& res)
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{
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using parent_context_t = typename Context::template partial<N - 1>;
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using CurrentMW = typename std::tuple_element<N, typename std::remove_reference<Container>::type>::type;
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if (cc.template enabled<CurrentMW>(N))
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{
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after_handler_call<CurrentMW, Context, parent_context_t>(std::get<N>(middlewares), req, res, ctx, static_cast<parent_context_t&>(ctx));
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}
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}
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template<typename CallCriteria, int N, typename Context, typename Container>
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typename std::enable_if<(N > 0)>::type after_handlers_call_helper(const CallCriteria& cc, Container& middlewares, Context& ctx, request& req, response& res)
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{
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using parent_context_t = typename Context::template partial<N - 1>;
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using CurrentMW = typename std::tuple_element<N, typename std::remove_reference<Container>::type>::type;
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if (cc.template enabled<CurrentMW>(N))
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{
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after_handler_call<CurrentMW, Context, parent_context_t>(std::get<N>(middlewares), req, res, ctx, static_cast<parent_context_t&>(ctx));
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}
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after_handlers_call_helper<CallCriteria, N - 1, Context, Container>(cc, middlewares, ctx, req, res);
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}
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// A CallCriteria that accepts only global middleware
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struct middleware_call_criteria_only_global
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{
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template<typename MW>
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constexpr bool enabled(int) const
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{
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return is_middleware_global<MW>::value;
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}
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};
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template<typename F, typename... Args>
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typename std::enable_if<black_magic::CallHelper<F, black_magic::S<Args...>>::value, void>::type
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wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
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{
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static_assert(!std::is_same<void, decltype(f(std::declval<Args>()...))>::value,
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"Handler function cannot have void return type; valid return types: string, int, crow::response, crow::returnable");
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res = crow::response(f(std::forward<Args>(args)...));
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res.end();
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}
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template<typename F, typename... Args>
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typename std::enable_if<
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!black_magic::CallHelper<F, black_magic::S<Args...>>::value &&
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black_magic::CallHelper<F, black_magic::S<crow::request&, Args...>>::value,
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void>::type
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wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
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{
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static_assert(!std::is_same<void, decltype(f(std::declval<crow::request>(), std::declval<Args>()...))>::value,
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"Handler function cannot have void return type; valid return types: string, int, crow::response, crow::returnable");
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res = crow::response(f(req, std::forward<Args>(args)...));
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res.end();
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}
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template<typename F, typename... Args>
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typename std::enable_if<
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!black_magic::CallHelper<F, black_magic::S<Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<crow::request&, Args...>>::value &&
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black_magic::CallHelper<F, black_magic::S<crow::response&, Args...>>::value,
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void>::type
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wrapped_handler_call(crow::request& /*req*/, crow::response& res, const F& f, Args&&... args)
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{
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static_assert(std::is_same<void, decltype(f(std::declval<crow::response&>(), std::declval<Args>()...))>::value,
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"Handler function with response argument should have void return type");
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f(res, std::forward<Args>(args)...);
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}
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template<typename F, typename... Args>
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typename std::enable_if<
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!black_magic::CallHelper<F, black_magic::S<Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<crow::request&, Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<crow::response&, Args...>>::value &&
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black_magic::CallHelper<F, black_magic::S<const crow::request&, crow::response&, Args...>>::value,
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void>::type
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wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
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{
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static_assert(std::is_same<void, decltype(f(std::declval<crow::request&>(), std::declval<crow::response&>(), std::declval<Args>()...))>::value,
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"Handler function with response argument should have void return type");
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f(req, res, std::forward<Args>(args)...);
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}
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// wrapped_handler_call transparently wraps a handler call behind (req, res, args...)
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template<typename F, typename... Args>
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typename std::enable_if<
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!black_magic::CallHelper<F, black_magic::S<Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<crow::request&, Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<crow::response&, Args...>>::value &&
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!black_magic::CallHelper<F, black_magic::S<const crow::request&, crow::response&, Args...>>::value,
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void>::type
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wrapped_handler_call(crow::request& req, crow::response& res, const F& f, Args&&... args)
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{
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static_assert(std::is_same<void, decltype(f(std::declval<crow::request&>(), std::declval<crow::response&>(), std::declval<Args>()...))>::value,
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"Handler function with response argument should have void return type");
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f(req, res, std::forward<Args>(args)...);
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}
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template<bool Reversed>
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struct middleware_call_criteria_dynamic
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{};
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template<>
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struct middleware_call_criteria_dynamic<false>
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{
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middleware_call_criteria_dynamic(const std::vector<int>& indices):
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indices(indices), slider(0) {}
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template<typename>
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bool enabled(int mw_index) const
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{
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if (slider < int(indices.size()) && indices[slider] == mw_index)
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{
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slider++;
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return true;
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}
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return false;
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}
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private:
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const std::vector<int>& indices;
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mutable int slider;
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};
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template<>
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struct middleware_call_criteria_dynamic<true>
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{
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middleware_call_criteria_dynamic(const std::vector<int>& indices):
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indices(indices), slider(int(indices.size()) - 1) {}
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template<typename>
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bool enabled(int mw_index) const
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{
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if (slider >= 0 && indices[slider] == mw_index)
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{
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slider--;
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return true;
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}
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return false;
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}
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private:
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const std::vector<int>& indices;
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mutable int slider;
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};
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} // namespace detail
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} // namespace crow
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