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construct/include/ircd/json.h
Jason Volk d9a4f06bf6 ircd: Employ namespace scope extensions from c++1z/gnu++14.
This is not a move to c++17. If the compiler happens to have support
for c++17 namespace scope resolution, they have been kind enough to
backport it to gnu++14. This limits our support for really old c++14
compilers, but that was limited anyway. GCC 6.1 and clang 3.6 tested.
2017-09-08 03:47:46 -07:00

112 lines
3.9 KiB
C++

/*
* Copyright (C) 2017 Charybdis Development Team
* Copyright (C) 2017 Jason Volk <jason@zemos.net>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice is present in all copies.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#define HAVE_IRCD_JSON_H
//
// The IRCd JSON subsystem is meant to be a fast, safe, and extremely
// lightweight interface. We have taken a somewhat non-traditional approach
// and it's important for the developer to understand a few things.
//
// Most JSON interfaces are functions to convert some JSON input to and from
// text into native-machine state like JSON.parse() for JS, boost::ptree, etc.
// For a parsing operation, they make a pass recursing over the entire text,
// allocating native structures, copying data into them, indexing their keys,
// and perhaps performing native-type conversions and checks to present the
// user with a final tree of machine-state usable in their language. The
// original input is then discarded.
//
// Instead, we are interested in having the ability to *compute directly over
// JSON text* itself, and perform the allocating, indexing, copying and
// converting entirely at the time and place of our discretion -- if ever.
//
// The core of this system is a robust and efficient abstract formal grammar
// built with boost::spirit. The formal grammar provides a *proof of robust-
// ness*: security vulnerabilities are more easily spotted by vetting this
// grammar rather than laboriously tracing the program flow of an informal
// handwritten parser.
//
// Next we have taught boost::spirit how to parse into std::string_view rather
// than std::string. Parsing is now a composition of pointers into the original
// string of JSON. No dynamic allocation ever takes place. No copying of data
// ever takes place. IRCd can service an entire request from the original
// network input with absolutely minimal requisite cost.
//
// The output side is also ambitious but probably a little more friendly to
// the developer. We leverage boost::spirit here also providing *formally
// proven* output safety. In other words, the grammar prevents exploits like
// injecting and terminating JSON as it composes the output.
//
namespace ircd::json
{
IRCD_EXCEPTION(ircd::error, error);
IRCD_EXCEPTION(error, parse_error);
IRCD_EXCEPTION(error, print_error);
IRCD_EXCEPTION(error, type_error);
IRCD_EXCEPTION(error, not_found);
struct array;
struct object;
struct value;
struct index;
enum type
{
STRING = 0,
OBJECT = 1,
ARRAY = 2,
NUMBER = 3,
LITERAL = 4,
};
enum type type(const string_view &);
enum type type(const string_view &, std::nothrow_t);
using path = std::initializer_list<string_view>;
std::ostream &operator<<(std::ostream &, const path &);
}
#include "json/array.h"
#include "json/object.h"
#include "json/value.h"
#include "json/index.h"
#include "json/tuple.h"
namespace ircd
{
using json::operator<<;
}
inline std::ostream &
ircd::json::operator<<(std::ostream &s, const path &p)
{
auto it(std::begin(p));
if(it != std::end(p))
{
s << *it;
++it;
}
for(; it != std::end(p); ++it)
s << '.' << *it;
return s;
}