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-rw-r--r--include/jsoncons_ext/jsonpath/flatten.hpp432
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diff --git a/include/jsoncons_ext/jsonpath/flatten.hpp b/include/jsoncons_ext/jsonpath/flatten.hpp
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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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