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construct/include/ircd/json/value.h

311 lines
8.2 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_VALUE_H
namespace ircd::json
{
struct value;
using values = std::initializer_list<value>;
size_t serialized(const bool &);
size_t serialized(const value *const &begin, const value *const &end);
size_t serialized(const values &);
string_view stringify(mutable_buffer &, const value *const &begin, const value *const &end);
}
/// A primitive of the ircd::json system representing a value at runtime.
///
/// This holds state for values apropos a JSON object or array. Value's
/// data can either be in the form of a JSON string or it can be some native
/// machine state. The serial flag indicates the former.
///
/// Value can can hold any of the JSON types in either of these states.
/// This is accomplished with runtime switching and branching but this is
/// still lightweight and without a vtable pointer. The structure is just
/// the size of two pointers like a string_view; we commandeer bits of the
/// second word to hold type, flags, and length information. Thus we can hold
/// large vectors of values at 16 byte alignment and not 24 byte.
///
/// Value is capable of allocation and ownership of its internal data and copy
/// semantics. This is primarily to support recursion and various developer
/// conveniences like nested initializer_list's etc. It is better to
/// std::move() a value than copy it, but the full copy semantic is supported;
/// however, if serial=false then a copy will stringify the data into JSON and
/// the destination will be serial=true,alloc=true; thus copying of complex
/// native values never occurs.
///
/// Take careful note of a quirk with `operator string_view()`: when the
/// value is a STRING type string_view()'ing the value will never show
/// the string with surrounding quotes in view. This is because the value
/// accepts both quoted and unquoted strings as input from the developer, then
/// always serializes correctly; unquoted strings are more natural to work
/// with. This does not apply to other types like OBJECT and array as
/// string_view()'ing those when in a serial state will show surrounding '{'
/// etc.
///
struct ircd::json::value
{
union // xxx std::variant
{
int64_t integer;
double floating;
const char *string;
const struct value *array;
const struct member *object;
};
uint64_t len : 57; ///< length indicator
enum type type : 3; ///< json::type indicator
uint64_t serial : 1; ///< only *string is used. type indicates JSON
uint64_t alloc : 1; ///< indicates the pointer for type is owned
uint64_t floats : 1; ///< for NUMBER type, integer or floating
using create_string_closure = std::function<void (mutable_buffer &)>;
void create_string(const size_t &len, const create_string_closure &);
public:
bool null() const; ///< literal null or assets are really null
bool empty() const; ///< null() or assets are empty
bool undefined() const;
bool operator!() const; ///< null() or undefined() or empty() or asset Falsy
operator string_view() const; ///< NOTE unquote()'s the string value
explicit operator double() const;
explicit operator int64_t() const;
explicit operator std::string() const; ///< NOTE full stringify() of value
template<size_t N> value(const char (&)[N], const enum type &);
value(const string_view &sv, const enum type &);
value(const char *const &, const enum type &);
explicit value(const int64_t &);
explicit value(const double &);
explicit value(const bool &);
template<size_t N> value(const char (&)[N]);
value(const string_view &sv);
value(const char *const &s);
value(const struct member *const &, const size_t &len);
value(std::unique_ptr<const struct member[]> &&, const size_t &len); // alloc = true
value(const struct value *const &, const size_t &len);
value(std::unique_ptr<const struct value[]> &&, const size_t &len); // alloc = true
value(const members &); // alloc = true
value(const nullptr_t &);
value();
value(value &&) noexcept;
value(const value &);
value &operator=(value &&) noexcept;
value &operator=(const value &);
~value() noexcept;
friend bool operator==(const value &a, const value &b);
friend bool operator!=(const value &a, const value &b);
friend bool operator<=(const value &a, const value &b);
friend bool operator>=(const value &a, const value &b);
friend bool operator<(const value &a, const value &b);
friend bool operator>(const value &a, const value &b);
friend enum type type(const value &a);
friend bool defined(const value &);
friend size_t serialized(const value &);
friend string_view stringify(mutable_buffer &, const value &);
friend std::ostream &operator<<(std::ostream &, const value &);
};
static_assert(sizeof(ircd::json::value) == 16, "");
inline
ircd::json::value::value()
:string{nullptr}
,len{0}
,type{STRING}
,serial{false}
,alloc{false}
,floats{false}
{}
inline
ircd::json::value::value(const string_view &sv,
const enum type &type)
:string{sv.data()}
,len{sv.size()}
,type{type}
,serial{type == STRING? surrounds(sv, '"') : true}
,alloc{false}
,floats{false}
{}
inline
ircd::json::value::value(const char *const &str,
const enum type &type)
:value{string_view{str}, type}
{}
inline
ircd::json::value::value(const char *const &str)
:value{string_view{str}}
{}
inline
ircd::json::value::value(const string_view &sv)
:value{sv, json::type(sv, std::nothrow)}
{}
template<size_t N>
ircd::json::value::value(const char (&str)[N])
:value{string_view{str, strnlen(str, N)}}
{}
template<size_t N>
ircd::json::value::value(const char (&str)[N],
const enum type &type)
:value{string_view{str, strnlen(str, N)}, type}
{}
inline
ircd::json::value::value(const nullptr_t &)
:value
{
literal_null, type::LITERAL
}{}
inline
ircd::json::value::value(const bool &boolean)
:value
{
boolean? literal_true : literal_false, type::LITERAL
}{}
inline
ircd::json::value::value(const struct value *const &array,
const size_t &len)
:array{array}
,len{len}
,type{ARRAY}
,serial{false}
,alloc{false}
,floats{false}
{
}
inline
ircd::json::value::value(std::unique_ptr<const struct value[]> &&array,
const size_t &len)
:array{array.get()}
,len{len}
,type{ARRAY}
,serial{false}
,alloc{true}
,floats{false}
{
array.release();
}
inline
ircd::json::value::value(const struct member *const &object,
const size_t &len)
:object{object}
,len{len}
,type{OBJECT}
,serial{false}
,alloc{false}
,floats{false}
{}
inline
ircd::json::value::value(std::unique_ptr<const struct member[]> &&object,
const size_t &len)
:object{object.get()}
,len{len}
,type{OBJECT}
,serial{false}
,alloc{true}
,floats{false}
{
object.release();
}
inline
ircd::json::value::value(const int64_t &integer)
:integer{integer}
,len{0}
,type{NUMBER}
,serial{false}
,alloc{false}
,floats{false}
{}
inline
ircd::json::value::value(const double &floating)
:floating{floating}
,len{0}
,type{NUMBER}
,serial{false}
,alloc{false}
,floats{true}
{}
inline
ircd::json::value::value(value &&other)
noexcept
:integer{other.integer}
,len{other.len}
,type{other.type}
,serial{other.serial}
,alloc{other.alloc}
,floats{other.floats}
{
other.alloc = false;
}
inline ircd::json::value &
ircd::json::value::operator=(value &&other)
noexcept
{
this->~value();
integer = other.integer;
len = other.len;
type = other.type;
serial = other.serial;
alloc = other.alloc;
other.alloc = false;
floats = other.floats;
return *this;
}
inline bool
ircd::json::defined(const value &a)
{
return !a.undefined();
}
inline enum ircd::json::type
ircd::json::type(const value &a)
{
return a.type;
}
inline size_t
ircd::json::serialized(const bool &b)
{
constexpr const size_t t
{
strlen("true")
};
constexpr const size_t f
{
strlen("false")
};
return b? t : f;
}