//
// Copyright (c) 2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/vinniefalco/CppCon2017
//
#include <cstdio>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <string>
#include <string_view>
#include <type_traits>
#include <vector>
using namespace std;
//------------------------------------------------------------------------------
//
// Message Container
//
//------------------------------------------------------------------------------
/// Holds an HTTP message
template<bool isRequest, class Body, class Fields>
struct message;
/// Holds an HTTP request
template<class Body, class Fields>
struct message<true, Body, Fields> : Fields,
private Body::value_type
{
int version;
string_view method() const
{
return this->get_method();
}
void method(string_view s)
{
this->set_method(s);
}
string_view target() const
{
return this->get_target();
}
void target(string_view s)
{
this->set_target(s);
}
typename Body::value_type const&
body() const
{
return *this;
}
typename Body::value_type&
body()
{
return *this;
}
};
/// Holds an HTTP response
template<class Body, class Fields>
struct message<false, Body, Fields> : Fields,
private Body::value_type
{
int version;
int status;
string_view reason() const
{
return this->get_reason();
}
void reason(string_view s)
{
this->set_reason(s);
}
typename Body::value_type const&
body() const
{
return *this;
}
typename Body::value_type&
body()
{
return *this;
}
};
//------------------------------------------------------------------------------
//
// Body
//
//------------------------------------------------------------------------------
/// `true_type` if B meets the requirements of Body
template<class B, class = void>
struct is_body : false_type
{
};
template<class B>
struct is_body<B, void_t<
typename B::value_type,
decltype(
B::write(
declval<ostream&>(),
declval<typename B::value_type const&>()),
(void)0)
>> : true_type
{
};
/// A Body that uses a string container
struct string_body
{
using value_type = string;
static void write(
ostream& os, string const& body)
{
os << body;
}
};
/// A Body that uses a vector container
template<class T>
struct vector_body
{
using value_type = vector<T>;
static void write(
ostream& os, vector<T> const& body)
{
os.write(body.data(), body.size());
}
};
/// A Body that uses a list container
template<class T>
struct list_body
{
using value_type = list<T>;
static void write(
ostream& os, list<T> const& body)
{
for(auto const& t : body)
os << t;
}
};
/// A Body using file contents
struct file_body
{
using value_type = string; // Path to file
static void write(
ostream& os, string const& path)
{
size_t n;
char buf[4096];
FILE* f = fopen(path.c_str(), "rb");
while((n = fread(buf, 1, sizeof(buf), f)))
os.write(buf, n);
fclose(f);
}
};
/// An empty body
struct empty_body
{
struct value_type {};
static void write(ostream&, value_type const&)
{
// Do nothing
}
};
//------------------------------------------------------------------------------
//
// Fields Container
//
//------------------------------------------------------------------------------
/// A container for HTTP fields
template<class Allocator>
struct basic_fields
{
void set(string_view, string_view);
string_view operator[](string_view) const;
protected:
string_view get_method() const noexcept;
void set_method(string_view);
string_view get_target() const noexcept;
void set_target(string_view);
string_view get_reason() const noexcept;
void set_reason(string_view);
};
//------------------------------------------------------------------------------
//
// Type Aliases
//
//------------------------------------------------------------------------------
/// A container for HTTP fields using the default allocator
using fields = basic_fields<std::allocator<char>>;
/// Holds an HTTP request
template<class Body, class Fields = fields>
using request = message<true, Body, Fields>;
/// Holds an HTTP response
template<class Body, class Fields = fields>
using response = message<false, Body, Fields>;
//------------------------------------------------------------------------------
//
// Serialization
//
//------------------------------------------------------------------------------
/// Serialize the HTTP header to an ostream
template<bool isRequest, class Body, class Fields>
void write_header(ostream&,
message<isRequest, Body, Fields> const&)
{
}
/// Serialize an HTTP Message
template<bool isRequest, class Body, class Fields>
void write(ostream& os,
message<isRequest, Body, Fields> const& msg)
{
static_assert(is_body<Body>::value,
"Body requirements not met");
write_header(os, msg);
Body::write(os, msg.body());
}
//------------------------------------------------------------------------------
//
// Tests
//
//------------------------------------------------------------------------------
// Error: missing value_type
struct invalid_body_1
{
using body_type = string;
static void write(
ostream& os, body_type const& body)
{
os.write(body.data(), body.size());
}
};
// Error: wrong signature for write
struct invalid_body_2
{
using value_type = string;
static void write(ostream& os)
{
os << "void";
}
};
static_assert(is_body<string_body>::value, "");
static_assert(is_body<vector_body<char>>::value, "");
static_assert(is_body<list_body<string>>::value, "");
static_assert(is_body<file_body>::value, "");
static_assert(is_body<empty_body>::value, "");
static_assert(! is_body<invalid_body_1>::value, "");
static_assert(! is_body<invalid_body_2>::value, "");
int
main()
{
{
request<string_body> req;
write(cout, req);
}
{
response<vector_body<char>> res;
write(cout, res);
}
{
response<list_body<string>> res;
write(cout, res);
}
{
response<empty_body> res;
write(cout, res);
}
}
