construct/include/ircd/json/array.h

// 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_ARRAY_H

namespace ircd::json
{
	struct array;

	bool empty(const array &);
	bool operator!(const array &);
	size_t size(const array &);

	size_t serialized(const string_view *const &begin, const string_view *const &end);
	size_t serialized(const std::string *const &begin, const std::string *const &end);
	size_t serialized(const array &);

	string_view stringify(mutable_buffer &buf, const string_view *const &begin, const string_view *const &end);
	string_view stringify(mutable_buffer &buf, const std::string *const &begin, const std::string *const &end);
	string_view stringify(mutable_buffer &, const array &);
	std::ostream &operator<<(std::ostream &, const array &);
}

/// Lightweight interface to a JSON array string.
///
/// This object accepts queries with numerical indexing. The same parsing
/// approach is used in ircd::json::object and that is important to note here:
/// iterating this array by incrementing your own numerical index and making
/// calls into this object is NOT efficient. Simply put, do not do something
/// like `for(int x=0; x<array.count(); x++) array.at(x)` as that will parse
/// the array from the beginning on every single increment. Instead, use the
/// provided iterator object.
///
struct ircd::json::array
:string_view
{
	struct const_iterator;

	using value_type = const string_view;
	using pointer = value_type *;
	using reference = value_type &;
	using iterator = const_iterator;
	using size_type = size_t;
	using difference_type = ptrdiff_t;

	static const uint max_recursion_depth;

	const_iterator end() const;
	const_iterator begin() const;
	const_iterator find(size_t i) const;

	bool empty() const;
	size_t count() const;
	size_t size() const;

	template<class T> T at(const size_t &i) const;
	string_view at(const size_t &i) const;
	string_view operator[](const size_t &i) const;

	explicit operator std::string() const;

	using string_view::string_view;

	template<class it> static size_t serialized(const it &b, const it &e);
	template<class it> static string_view stringify(mutable_buffer &, const it &b, const it &e);
};

namespace ircd::json
{
	bool operator==(const array::const_iterator &, const array::const_iterator &);
	bool operator!=(const array::const_iterator &, const array::const_iterator &);
	bool operator<=(const array::const_iterator &, const array::const_iterator &);
	bool operator>=(const array::const_iterator &, const array::const_iterator &);
	bool operator<(const array::const_iterator &, const array::const_iterator &);
	bool operator>(const array::const_iterator &, const array::const_iterator &);
}

struct ircd::json::array::const_iterator
{
	using value_type = const string_view;
	using pointer = value_type *;
	using reference = value_type &;
	using iterator = const_iterator;
	using size_type = size_t;
	using difference_type = ptrdiff_t;
	using iterator_category = std::forward_iterator_tag;

  protected:
	friend class array;

	const char *start {nullptr};
	const char *stop {nullptr};
	string_view state;

	const_iterator(const char *const &start, const char *const &stop)
	:start{start}
	,stop{stop}
	{}

  public:
	value_type *operator->() const               { return &state;                                  }
	value_type &operator*() const                { return *operator->();                           }

	const_iterator &operator++();

	const_iterator() = default;

	friend bool operator==(const const_iterator &, const const_iterator &);
	friend bool operator!=(const const_iterator &, const const_iterator &);
	friend bool operator<=(const const_iterator &, const const_iterator &);
	friend bool operator>=(const const_iterator &, const const_iterator &);
	friend bool operator<(const const_iterator &, const const_iterator &);
	friend bool operator>(const const_iterator &, const const_iterator &);
};

template<class T>
T
ircd::json::array::at(const size_t &i)
const try
{
	return lex_cast<T>(at(i));
}
catch(const bad_lex_cast &e)
{
	throw type_error
	{
		"indice %zu must cast to type %s", i, typeid(T).name()
	};
}