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// file : brep/module -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
// license : MIT; see accompanying LICENSE file
#ifndef BREP_MODULE
#define BREP_MODULE
#include <utility> // move()
#include <web/module>
#include <brep/diagnostics>
namespace brep
{
// Bring in commonly used names from the web namespace.
//
// @@ Maybe doing using namespace is the right way to handle this.
// There will, however, most likely be a conflict between
// web::module and our module. Or maybe not, need to try.
//
using web::status_code;
using web::name_value;
using web::name_values;
using web::request;
using web::response;
using web::log;
// This exception is used to signal that the request is invalid
// (4XX codes) rather than that it could not be processed (5XX).
// By default 422 is returned, which means the request was
// semantically invalid.
//
struct invalid_request
{
status_code status {422};
std::string description;
//@@ Maybe optional "try again" link?
//
invalid_request (std::string d, status_code s = 422)
: status (s), description (std::move (d)) {}
};
// And this exception indicated a server error (5XX). In particular,
// it is thrown by the fail diagnostics stream and is caught by the
// module implementation where it is both logged as an error and
// returned to the user with the 5XX status code.
//
struct server_error
{
diag_data data;
server_error (diag_data&& d): data (std::move (d)) {}
};
// Every module member function that needs to produce any diagnostics
// shall begin with:
//
// MODULE_DIAG;
//
// This will instantiate the fail, error, warn, info, and trace
// diagnostics streams with the function's name.
//
#define MODULE_DIAG \
const fail_mark<server_error> fail (__PRETTY_FUNCTION__); \
const basic_mark error (severity::error, \
this->log_writer_, \
__PRETTY_FUNCTION__); \
const basic_mark warn (severity::warning, \
this->log_writer_, \
__PRETTY_FUNCTION__); \
const basic_mark info (severity::info, \
this->log_writer_, \
__PRETTY_FUNCTION__); \
const basic_mark trace (severity::info, \
this->log_writer_, \
__PRETTY_FUNCTION__)
// Adaptation of the web::module to our needs.
//
class module: public web::module
{
public:
virtual void
handle (request&, response&) = 0;
// Diagnostics.
//
protected:
// Trace verbosity level.
//
// 0 - tracing disabled.
// 1 - @@ TODO: document
// 2 - @@ TODO: document
//
// While uint8 is more than enough, use uint16 for the ease of printing.
//
std::uint16_t verb_ {0};
template <class F> void level1 (const F& f) const {if (verb_ >= 1) f ();}
template <class F> void level2 (const F& f) const {if (verb_ >= 2) f ();}
// Implementation details.
//
protected:
module ();
virtual void
handle (request&, response&, log&);
// Diagnostics implementation details.
//
private:
log* log_ {nullptr}; // Diagnostics backend provided by the web server.
void
log_write (diag_data&&) const;
protected:
const diag_epilogue log_writer_;
};
}
#endif // BREP_MODULE
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