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construct/include/ircd/json/util.h

93 lines
2.6 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 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. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_JSON_UTIL_H
// This section contains utilities which are useful other parts of ircd::json
// or developers directly. This interface itself (though not its definition)
// has little dependence on other headers in ircd::json. In contrast, a suite
// of rich developer tools which depend on various assets in ircd::json are
// found in tool.h instead.
namespace ircd::json
{
template<size_t SIZE> struct buffer;
using name_hash_t = size_t;
constexpr name_hash_t name_hash(const string_view name);
constexpr name_hash_t operator ""_(const char *const name, const size_t len);
size_t serialized(const string_view &);
string_view stringify(mutable_buffer &, const string_view &);
template<class... T> size_t print(const mutable_buffer &buf, T&&... t);
// Validate JSON - checks if valid JSON (not canonical).
bool valid(const string_view &, std::nothrow_t) noexcept;
void valid(const string_view &);
std::string why(const string_view &);
// (Internal) validates output
void valid_output(const string_view &, const size_t &expected);
// Transforms input into escaped output only
string_view escape(const mutable_buffer &out, const string_view &in);
}
/// Alternative to `json::strung` which uses a fixed array rather than an
/// allocated string as the target.
template<size_t SIZE>
struct ircd::json::buffer
:string_view
{
std::array<char, SIZE> b;
template<class... T>
buffer(T&&... t)
:string_view{stringify(b, std::forward<T>(t)...)}
{}
};
/// Convenience template using the syntax print(mutable_buffer, ...)
/// which stringifies with null termination into buffer.
///
template<class... T>
size_t
ircd::json::print(const mutable_buffer &buf,
T&&... t)
{
if(unlikely(!size(buf)))
return 0;
mutable_buffer out
{
data(buf), size(buf) - 1
};
const auto sv
{
stringify(out, std::forward<T>(t)...)
};
buf[sv.size()] = '\0';
valid_output(sv, size(sv)); // no size expectation check
return sv.size();
}
constexpr ircd::json::name_hash_t
ircd::json::operator ""_(const char *const text, const size_t len)
{
return name_hash(string_view(text, len));
}
constexpr ircd::json::name_hash_t
ircd::json::name_hash(const string_view name)
{
return ircd::hash(name);
}