//
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// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/json
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//
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#ifndef BOOST_JSON_IMPL_OBJECT_HPP
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#define BOOST_JSON_IMPL_OBJECT_HPP
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#include <boost/json/value.hpp>
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#include <iterator>
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#include <cmath>
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#include <type_traits>
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#include <utility>
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BOOST_JSON_NS_BEGIN
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namespace detail {
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// Objects with size less than or equal
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// to this number will use a linear search
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// instead of the more expensive hash function.
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static
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constexpr
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std::size_t
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small_object_size_ = 18;
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BOOST_STATIC_ASSERT(
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small_object_size_ <
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BOOST_JSON_MAX_STRUCTURED_SIZE);
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} // detail
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//----------------------------------------------------------
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struct alignas(key_value_pair)
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object::table
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{
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std::uint32_t size = 0;
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std::uint32_t capacity = 0;
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std::uintptr_t salt = 0;
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#if defined(_MSC_VER) && BOOST_JSON_ARCH == 32
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// VFALCO If we make key_value_pair smaller,
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// then we might want to revisit this
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// padding.
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BOOST_STATIC_ASSERT(
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sizeof(key_value_pair) == 32);
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char pad[4] = {}; // silence warnings
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#endif
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constexpr table();
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// returns true if we use a linear
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// search instead of the hash table.
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bool is_small() const noexcept
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{
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return capacity <=
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detail::small_object_size_;
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}
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key_value_pair&
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operator[](
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std::size_t pos) noexcept
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{
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return reinterpret_cast<
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key_value_pair*>(
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this + 1)[pos];
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}
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// VFALCO This is exported for tests
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BOOST_JSON_DECL
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std::size_t
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digest(string_view key) const noexcept;
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inline
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index_t&
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bucket(std::size_t hash) noexcept;
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inline
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index_t&
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bucket(string_view key) noexcept;
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inline
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void
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clear() noexcept;
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static
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inline
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table*
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allocate(
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std::size_t capacity,
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std::uintptr_t salt,
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storage_ptr const& sp);
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static
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void
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deallocate(
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table* p,
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storage_ptr const& sp) noexcept
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{
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if(p->capacity == 0)
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return;
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if(p->is_small())
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sp->deallocate(p,
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sizeof(table) + p->capacity * (
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sizeof(key_value_pair) +
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sizeof(index_t)));
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else
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sp->deallocate(p,
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sizeof(table) + p->capacity *
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sizeof(key_value_pair));
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}
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};
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//----------------------------------------------------------
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class object::revert_construct
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{
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object* obj_;
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BOOST_JSON_DECL
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void
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destroy() noexcept;
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public:
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explicit
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revert_construct(
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object& obj) noexcept
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: obj_(&obj)
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{
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}
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~revert_construct()
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{
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if(! obj_)
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return;
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destroy();
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}
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void
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commit() noexcept
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{
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obj_ = nullptr;
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}
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};
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//----------------------------------------------------------
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class object::revert_insert
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{
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object* obj_;
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std::size_t size_;
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BOOST_JSON_DECL
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void
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destroy() noexcept;
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public:
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explicit
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revert_insert(
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object& obj) noexcept
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: obj_(&obj)
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, size_(obj_->size())
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{
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}
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~revert_insert()
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{
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if(! obj_)
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return;
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destroy();
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obj_->t_->size = static_cast<
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index_t>(size_);
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}
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void
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commit() noexcept
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{
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obj_ = nullptr;
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}
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};
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//----------------------------------------------------------
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//
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// Iterators
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//
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//----------------------------------------------------------
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auto
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object::
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begin() noexcept ->
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iterator
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{
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return &(*t_)[0];
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}
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auto
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object::
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begin() const noexcept ->
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const_iterator
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{
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return &(*t_)[0];
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}
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auto
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object::
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cbegin() const noexcept ->
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const_iterator
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{
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return &(*t_)[0];
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}
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auto
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object::
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end() noexcept ->
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iterator
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{
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return &(*t_)[t_->size];
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}
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auto
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object::
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end() const noexcept ->
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const_iterator
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{
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return &(*t_)[t_->size];
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}
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auto
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object::
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cend() const noexcept ->
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const_iterator
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{
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return &(*t_)[t_->size];
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}
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auto
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object::
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rbegin() noexcept ->
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reverse_iterator
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{
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return reverse_iterator(end());
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}
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auto
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object::
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rbegin() const noexcept ->
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const_reverse_iterator
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{
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return const_reverse_iterator(end());
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}
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auto
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object::
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crbegin() const noexcept ->
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const_reverse_iterator
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{
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return const_reverse_iterator(end());
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}
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auto
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object::
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rend() noexcept ->
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reverse_iterator
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{
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return reverse_iterator(begin());
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}
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auto
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object::
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rend() const noexcept ->
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const_reverse_iterator
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{
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return const_reverse_iterator(begin());
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}
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auto
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object::
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crend() const noexcept ->
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const_reverse_iterator
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{
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return const_reverse_iterator(begin());
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}
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//----------------------------------------------------------
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//
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// Capacity
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//
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//----------------------------------------------------------
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bool
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object::
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empty() const noexcept
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{
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return t_->size == 0;
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}
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auto
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object::
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size() const noexcept ->
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std::size_t
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{
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return t_->size;
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}
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constexpr
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std::size_t
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object::
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max_size() noexcept
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{
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// max_size depends on the address model
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using min = std::integral_constant<std::size_t,
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(std::size_t(-1) - sizeof(table)) /
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(sizeof(key_value_pair) + sizeof(index_t))>;
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return min::value < BOOST_JSON_MAX_STRUCTURED_SIZE ?
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min::value : BOOST_JSON_MAX_STRUCTURED_SIZE;
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}
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auto
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object::
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capacity() const noexcept ->
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std::size_t
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{
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return t_->capacity;
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}
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//----------------------------------------------------------
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//
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// Lookup
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//
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//----------------------------------------------------------
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auto
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object::
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at(string_view key) ->
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value&
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{
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auto it = find(key);
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if(it == end())
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detail::throw_out_of_range(
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BOOST_CURRENT_LOCATION);
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return it->value();
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}
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auto
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object::
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at(string_view key) const ->
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value const&
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{
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auto it = find(key);
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if(it == end())
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detail::throw_out_of_range(
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BOOST_CURRENT_LOCATION);
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return it->value();
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}
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//----------------------------------------------------------
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template<class P, class>
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auto
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object::
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insert(P&& p) ->
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std::pair<iterator, bool>
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{
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key_value_pair v(
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std::forward<P>(p), sp_);
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return insert_impl(pilfer(v));
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}
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template<class M>
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auto
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object::
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insert_or_assign(
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string_view key, M&& m) ->
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std::pair<iterator, bool>
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{
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reserve(size() + 1);
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auto const result = find_impl(key);
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if(result.first)
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{
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value(std::forward<M>(m),
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sp_).swap(result.first->value());
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return { result.first, false };
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}
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key_value_pair kv(key,
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std::forward<M>(m), sp_);
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return { insert_impl(pilfer(kv),
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result.second), true };
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}
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template<class Arg>
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auto
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object::
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emplace(
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string_view key,
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Arg&& arg) ->
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std::pair<iterator, bool>
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{
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reserve(size() + 1);
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auto const result = find_impl(key);
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if(result.first)
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return { result.first, false };
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key_value_pair kv(key,
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std::forward<Arg>(arg), sp_);
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return { insert_impl(pilfer(kv),
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result.second), true };
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}
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//----------------------------------------------------------
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//
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// (private)
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//
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//----------------------------------------------------------
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template<class InputIt>
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void
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object::
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construct(
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InputIt first,
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InputIt last,
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std::size_t min_capacity,
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std::input_iterator_tag)
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{
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reserve(min_capacity);
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revert_construct r(*this);
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while(first != last)
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{
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insert(*first);
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++first;
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}
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r.commit();
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}
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template<class InputIt>
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void
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object::
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construct(
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InputIt first,
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InputIt last,
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std::size_t min_capacity,
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std::forward_iterator_tag)
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{
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auto n = static_cast<
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std::size_t>(std::distance(
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first, last));
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if( n < min_capacity)
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n = min_capacity;
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reserve(n);
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revert_construct r(*this);
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while(first != last)
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{
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insert(*first);
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++first;
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}
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r.commit();
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}
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template<class InputIt>
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void
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object::
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insert(
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InputIt first,
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InputIt last,
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std::input_iterator_tag)
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{
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// Since input iterators cannot be rewound,
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// we keep inserted elements on an exception.
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//
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while(first != last)
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{
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insert(*first);
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++first;
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}
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}
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template<class InputIt>
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void
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object::
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insert(
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InputIt first,
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InputIt last,
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std::forward_iterator_tag)
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{
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auto const n =
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static_cast<std::size_t>(
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std::distance(first, last));
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auto const n0 = size();
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if(n > max_size() - n0)
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detail::throw_length_error(
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"object too large",
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BOOST_CURRENT_LOCATION);
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reserve(n0 + n);
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revert_insert r(*this);
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while(first != last)
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{
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insert(*first);
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++first;
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}
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r.commit();
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}
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//----------------------------------------------------------
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namespace detail {
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unchecked_object::
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~unchecked_object()
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{
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if(! data_)
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return;
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if(sp_.is_not_shared_and_deallocate_is_trivial())
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return;
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value* p = data_;
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while(size_--)
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{
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p[0].~value();
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p[1].~value();
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p += 2;
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}
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}
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} // detail
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BOOST_JSON_NS_END
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#endif
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