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// Copyright 2021 Daniel Parker
// Distributed under the Boost license, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// See https://github.com/danielaparker/jsoncons for latest version
#ifndef JSONCONS_JSONPATH_FLATTEN_HPP
#define JSONCONS_JSONPATH_FLATTEN_HPP
#include <string>
#include <vector>
#include <memory>
#include <type_traits> // std::is_const
#include <limits> // std::numeric_limits
#include <utility> // std::move
#include <algorithm> // std::copy
#include <iterator> // std::back_inserter
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
namespace jsoncons { namespace jsonpath {
template <class CharT, class Sink>
std::size_t escape_string(const CharT* s, std::size_t length,
Sink& sink)
{
std::size_t count = 0;
const CharT* begin = s;
const CharT* end = s + length;
for (const CharT* it = begin; it != end; ++it)
{
CharT c = *it;
switch (c)
{
case '\\':
sink.push_back('\\');
sink.push_back('\\');
count += 2;
break;
case '\'':
sink.push_back('\\');
sink.push_back('\'');
count += 2;
break;
case '\b':
sink.push_back('\\');
sink.push_back('b');
count += 2;
break;
case '\f':
sink.push_back('\\');
sink.push_back('f');
count += 2;
break;
case '\n':
sink.push_back('\\');
sink.push_back('n');
count += 2;
break;
case '\r':
sink.push_back('\\');
sink.push_back('r');
count += 2;
break;
case '\t':
sink.push_back('\\');
sink.push_back('t');
count += 2;
break;
default:
sink.push_back(c);
++count;
break;
}
}
return count;
}
template<class Json>
void flatten_(const std::basic_string<typename Json::char_type>& parent_key,
const Json& parent_value,
Json& result)
{
using char_type = typename Json::char_type;
using string_type = std::basic_string<char_type>;
switch (parent_value.type())
{
case json_type::array_value:
{
if (parent_value.empty())
{
result.try_emplace(parent_key, parent_value);
}
else
{
for (std::size_t i = 0; i < parent_value.size(); ++i)
{
string_type key(parent_key);
key.push_back('[');
jsoncons::detail::from_integer(i,key);
key.push_back(']');
flatten_(key, parent_value.at(i), result);
}
}
break;
}
case json_type::object_value:
{
if (parent_value.empty())
{
result.try_emplace(parent_key, Json());
}
else
{
for (const auto& item : parent_value.object_range())
{
string_type key(parent_key);
key.push_back('[');
key.push_back('\'');
escape_string(item.key().data(), item.key().length(), key);
key.push_back('\'');
key.push_back(']');
flatten_(key, item.value(), result);
}
}
break;
}
default:
{
result[parent_key] = parent_value;
break;
}
}
}
template<class Json>
Json flatten(const Json& value)
{
Json result;
std::basic_string<typename Json::char_type> parent_key = {'$'};
flatten_(parent_key, value, result);
return result;
}
enum class unflatten_state
{
start,
expect_lbracket,
lbracket,
single_quoted_name_state,
double_quoted_name_state,
index_state,
expect_rbracket,
double_quoted_string_escape_char,
single_quoted_string_escape_char
};
template<class Json>
Json unflatten(const Json& value)
{
using char_type = typename Json::char_type;
using string_type = std::basic_string<char_type>;
if (JSONCONS_UNLIKELY(!value.is_object()))
{
JSONCONS_THROW(jsonpath_error(jsonpath_errc::argument_to_unflatten_invalid));
}
Json result;
for (const auto& item : value.object_range())
{
Json* part = &result;
string_type buffer;
unflatten_state state = unflatten_state::start;
auto it = item.key().begin();
auto last = item.key().end();
for (; it != last; ++it)
{
switch (state)
{
case unflatten_state::start:
{
switch (*it)
{
case '$':
state = unflatten_state::expect_lbracket;
break;
default:
break;
}
break;
}
case unflatten_state::expect_lbracket:
{
switch (*it)
{
case '[':
state = unflatten_state::lbracket;
break;
default:
JSONCONS_THROW(jsonpath_error(jsonpath_errc::invalid_flattened_key));
break;
}
break;
}
case unflatten_state::lbracket:
{
switch (*it)
{
case '\'':
state = unflatten_state::single_quoted_name_state;
break;
case '\"':
state = unflatten_state::double_quoted_name_state;
break;
case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8':case '9':
buffer.push_back(*it);
state = unflatten_state::index_state;
break;
default:
JSONCONS_THROW(jsonpath_error(jsonpath_errc::invalid_flattened_key));
break;
}
break;
}
case unflatten_state::single_quoted_name_state:
{
switch (*it)
{
case '\'':
if (it != last-2)
{
auto res = part->try_emplace(buffer,Json());
part = &(res.first->value());
}
else
{
auto res = part->try_emplace(buffer,item.value());
part = &(res.first->value());
}
buffer.clear();
state = unflatten_state::expect_rbracket;
break;
case '\\':
state = unflatten_state::single_quoted_string_escape_char;
break;
default:
buffer.push_back(*it);
break;
}
break;
}
case unflatten_state::double_quoted_name_state:
{
switch (*it)
{
case '\"':
if (it != last-2)
{
auto res = part->try_emplace(buffer,Json());
part = &(res.first->value());
}
else
{
auto res = part->try_emplace(buffer,item.value());
part = &(res.first->value());
}
buffer.clear();
state = unflatten_state::expect_rbracket;
break;
case '\\':
state = unflatten_state::double_quoted_string_escape_char;
break;
default:
buffer.push_back(*it);
break;
}
break;
}
case unflatten_state::double_quoted_string_escape_char:
switch (*it)
{
case '\"':
buffer.push_back('\"');
state = unflatten_state::double_quoted_name_state;
break;
case '\\':
buffer.push_back('\\');
state = unflatten_state::double_quoted_name_state;
break;
case '/':
buffer.push_back('/');
state = unflatten_state::double_quoted_name_state;
break;
case 'b':
buffer.push_back('\b');
state = unflatten_state::double_quoted_name_state;
break;
case 'f':
buffer.push_back('\f');
state = unflatten_state::double_quoted_name_state;
break;
case 'n':
buffer.push_back('\n');
state = unflatten_state::double_quoted_name_state;
break;
case 'r':
buffer.push_back('\r');
state = unflatten_state::double_quoted_name_state;
break;
case 't':
buffer.push_back('\t');
state = unflatten_state::double_quoted_name_state;
break;
default:
break;
}
break;
case unflatten_state::single_quoted_string_escape_char:
switch (*it)
{
case '\'':
buffer.push_back('\'');
state = unflatten_state::single_quoted_name_state;
break;
case '\\':
buffer.push_back('\\');
state = unflatten_state::double_quoted_name_state;
break;
case '/':
buffer.push_back('/');
state = unflatten_state::double_quoted_name_state;
break;
case 'b':
buffer.push_back('\b');
state = unflatten_state::double_quoted_name_state;
break;
case 'f':
buffer.push_back('\f');
state = unflatten_state::double_quoted_name_state;
break;
case 'n':
buffer.push_back('\n');
state = unflatten_state::double_quoted_name_state;
break;
case 'r':
buffer.push_back('\r');
state = unflatten_state::double_quoted_name_state;
break;
case 't':
buffer.push_back('\t');
state = unflatten_state::double_quoted_name_state;
break;
default:
break;
}
break;
case unflatten_state::index_state:
{
switch (*it)
{
case ']':
{
std::size_t n{0};
auto r = jsoncons::detail::to_integer(buffer.data(), buffer.size(), n);
if (r)
{
if (!part->is_array())
{
*part = Json(json_array_arg);
}
if (it != last-1)
{
if (n+1 > part->size())
{
Json& ref = part->emplace_back();
part = std::addressof(ref);
}
else
{
part = &part->at(n);
}
}
else
{
Json& ref = part->emplace_back(item.value());
part = std::addressof(ref);
}
}
buffer.clear();
state = unflatten_state::expect_lbracket;
break;
}
case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8':case '9':
buffer.push_back(*it);
break;
default:
JSONCONS_THROW(jsonpath_error(jsonpath_errc::invalid_flattened_key));
break;
}
break;
}
case unflatten_state::expect_rbracket:
{
switch (*it)
{
case ']':
state = unflatten_state::expect_lbracket;
break;
default:
JSONCONS_THROW(jsonpath_error(jsonpath_errc::invalid_flattened_key));
break;
}
break;
}
default:
JSONCONS_UNREACHABLE();
break;
}
}
}
return result;
}
}}
#endif
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