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Commits
| Author | SHA1 | Date | |
|---|---|---|---|
 Niels Lohmann
|
5d7d4a9ae6 | ||
|
Niels Lohmann
|
86ea63185e |
@@ -79,6 +79,7 @@ Some important things:
|
||||
* When using `get<your_type>()`, `your_type` **MUST** be [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). (There is a way to bypass this requirement described later.)
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* In function `from_json`, use function [`at()`](../api/basic_json/at.md) to access the object values rather than `operator[]`. In case a key does not exist, `at` throws an exception that you can handle, whereas `operator[]` exhibits undefined behavior.
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* You do not need to add serializers or deserializers for STL types like `std::vector`: the library already implements these.
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* If you control the type, consider defining `to_json`/`from_json` as `friend` functions inside the class ("hidden friends"). Argument-dependent lookup then only finds them for your type, which also avoids a [GCC < 11 compilation error](../home/faq.md#incomplete-detector-type-with-gcc-11).
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## Simplify your life with macros
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@@ -307,6 +307,51 @@ APP_CPPFLAGS += -frtti -fexceptions
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The code compiles successfully with [Android NDK](https://developer.android.com/ndk/index.html?hl=ml), Revision 9 - 11 (and possibly later) and [CrystaX's Android NDK](https://www.crystax.net/en/android/ndk) version 10.
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### Incomplete `detector` type with GCC < 11
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!!! question
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Why does GCC 10 or older fail with `invalid use of incomplete type 'struct nlohmann::detail::detector<..., to_json_function, ...>'` for a type that holds an `optional` member?
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This happens with GCC 10 and older in C++11/C++14 mode when all of these hold:
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- a class `Holder` has an `optional<Dummy>` member (e.g., `boost::optional`),
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- `Dummy` has a constructor taking a `json` value, and
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- `to_json` for `Holder` is a free function in the namespace of `Dummy`.
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```cpp
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class Dummy {
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public:
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explicit Dummy(const nlohmann::json& j);
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};
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class Holder {
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boost::optional<Dummy> d;
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};
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void to_json(nlohmann::json& j, const Holder& h); // triggers the error
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```
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To decide whether `Dummy` is copyable, the compiler checks whether a `Dummy` can be converted to `json`. That check
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looks up `to_json` via argument-dependent lookup, finds the unrelated `to_json` for `Holder`, and eventually asks again
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whether `Dummy` is copyable. GCC before version 11 turns this cycle into a hard error; GCC 11 and later, Clang, and
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C++17 mode compile the code. The same error shows up without this library whenever a constrained converting constructor
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is involved, so the library can't avoid it.
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To work around this, define `to_json` (and `from_json`) as a *hidden friend* inside the class. That way,
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argument-dependent lookup only finds it for `Holder`:
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```cpp
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class Holder {
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boost::optional<Dummy> d;
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friend void to_json(nlohmann::json& j, const Holder& h) { /* ... */ }
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};
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```
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The [`NLOHMANN_DEFINE_TYPE_INTRUSIVE`](../api/macros/nlohmann_define_type_intrusive.md) macros define hidden friends as
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well. See [#3669](https://github.com/nlohmann/json/issues/3669) for details.
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### Missing STL function
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!!! question "Questions"
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+168
-406
@@ -6061,240 +6061,21 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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{
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// the patch
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basic_json result(value_t::array);
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diff_recursively(result, source, target, path, 0);
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return result;
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}
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private:
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/// @brief two arrays or two objects @ref diff_iteratively is diffing
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struct diff_frame
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{
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diff_frame(const basic_json* source_, const basic_json* target_, const std::size_t path_length_) noexcept
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: source(source_), target(target_), path_length(path_length_)
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{}
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// declared for GCC's -Weffc++, which asks for them in a class with
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// pointer members and a non-trivial destructor; the exception
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// specifications are left implicit, as GCC 4.8 rejects explicit ones
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// that differ from them
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diff_frame(const diff_frame&) = default;
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diff_frame(diff_frame&&) = default;
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diff_frame& operator=(const diff_frame&) = default;
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diff_frame& operator=(diff_frame&&) = default;
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~diff_frame() = default;
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/// the values being diffed, both arrays or both objects
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const basic_json* source;
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const basic_json* target;
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/// the length of their path in `current_path`
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std::size_t path_length;
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/// arrays: the next index to diff
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std::size_t index = 0;
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/// objects: the next member of source to look at
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const_iterator member{}; // NOLINT(readability-redundant-member-init)
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/// objects: the keys common to both, in source's order
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std::vector<typename object_t::key_type> common_keys{}; // NOLINT(readability-redundant-member-init)
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/// objects: the next entry of common_keys
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std::size_t next_common = 0;
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/// objects: the "add" operations for keys only target has
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basic_json added_ops{}; // NOLINT(readability-redundant-member-init)
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};
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// The operations of a diff are built by the functions below rather than
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// where they are needed: building one takes several temporaries, and
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// unoptimized builds give each temporary a stack slot of its own in the
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// function it appears in. In diff_recursively, which is on the call stack
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// once per nesting level, that made every level cost kilobytes of stack.
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/// @brief append a "replace" operation for @a path with @a value to @a result
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static void diff_replace(basic_json& result, const string_t& path, const basic_json& value)
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{
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result.push_back(
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{
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{"op", "replace"}, {"path", path}, {"value", value}
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});
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}
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/// @brief append a "remove" operation for @a path to @a result
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static void diff_remove(basic_json& result, const string_t& path)
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{
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result.push_back(object(
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{
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{"op", "remove"}, {"path", path}
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}));
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}
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/// @brief append an "add" operation for @a path with @a value to @a result
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static void diff_add(basic_json& result, const string_t& path, const basic_json& value)
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{
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result.push_back(
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{
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{"op", "add"}, {"path", path}, {"value", value}
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});
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}
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/// @brief append the "remove" operations for the elements of array
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/// @a source from @a index on, and the "add" operations for the
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/// elements of array @a target from source's size on, to @a result
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static void diff_array_tails(basic_json& result, const basic_json& source, const basic_json& target,
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const string_t& path, const std::size_t index)
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{
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// remove my remaining elements, highest index first; appending
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// in that order avoids the quadratic reinsertion done before
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for (std::size_t j = source.size(); j > index; --j)
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{
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diff_remove(result, detail::concat<string_t>(path, '/', detail::to_string<string_t>(j - 1)));
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}
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// add other remaining elements
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for (std::size_t i = source.size(); i < target.size(); ++i)
|
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{
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diff_add(result, detail::concat<string_t>(path, "/-"), target[i]);
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}
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}
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/*!
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@brief compare the keys of objects @a source and @a target
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|
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If the keys both objects have are in the same order in both, and the keys
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only @a target has come after them, stores the keys common to both in
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source's order in @a common_keys, stores the "add" operations for the keys
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only @a target has in @a added_ops, and returns true: the caller then diffs
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the objects member by member. Otherwise, appends operations that remove
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every member of @a source and add every member of @a target to @a result,
|
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and returns false.
|
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*/
|
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static bool diff_object_keys(basic_json& result, const basic_json& source, const basic_json& target,
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const string_t& path, std::vector<typename object_t::key_type>& common_keys,
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basic_json& added_ops)
|
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{
|
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// first pass: record, for every source key, whether it is
|
||||
// common to both objects (in source's iteration order) or
|
||||
// was deleted (i.e., in source but not in target) -- this is
|
||||
// a by-product of the target.find() call already needed to
|
||||
// tell the two cases apart, so it adds no extra lookups. The
|
||||
// "remove" ops themselves are emitted later, interleaved
|
||||
// with the per-key diffs in the caller's fast path, to match
|
||||
// source's original iteration order (as the original,
|
||||
// pre-reordering-aware implementation did) instead of
|
||||
// grouping all removes before all per-key diffs.
|
||||
std::vector<typename object_t::key_type> common_keys_source_order;
|
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for (auto it = source.cbegin(); it != source.cend(); ++it)
|
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{
|
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if (target.find(it.key()) != target.end())
|
||||
{
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common_keys_source_order.push_back(it.key());
|
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}
|
||||
}
|
||||
|
||||
// second pass: find keys that were added (i.e., in target but
|
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// not in source), and record the keys common to both, in
|
||||
// target's iteration order -- again a by-product of the
|
||||
// source.find() call already needed to detect added keys. At
|
||||
// the same time, determine whether every added key comes
|
||||
// after every common key in target's order (a precondition
|
||||
// for the fast path, which only ever appends new keys
|
||||
// at the very end): for an object_t whose iteration order is
|
||||
// a pure function of the key set (e.g. the default std::map,
|
||||
// which always iterates in sorted key order), the order
|
||||
// check further below is always true and this whole
|
||||
// mechanism is effectively a no-op; it only matters for a
|
||||
// reorderable object_t such as the one backing `ordered_json`.
|
||||
// The patch ops for keys that were added (i.e., in target but not
|
||||
// in source) are built here so the fast path can reuse
|
||||
// them without a second source.find() per target key. Only
|
||||
// used by the fast path -- the slow (reordering) path
|
||||
// rebuilds "add" ops for every key itself.
|
||||
std::vector<typename object_t::key_type> common_keys_target_order;
|
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bool new_keys_form_suffix = true;
|
||||
bool seen_new_key = false;
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
if (source.find(it.key()) == source.end())
|
||||
{
|
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seen_new_key = true;
|
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diff_add(added_ops, detail::concat<string_t>(path, '/', detail::escape(it.key())), it.value());
|
||||
}
|
||||
else
|
||||
{
|
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common_keys_target_order.push_back(it.key());
|
||||
if (seen_new_key)
|
||||
{
|
||||
new_keys_form_suffix = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
|
||||
{
|
||||
// fast path: order of common keys already matches (or the
|
||||
// object_t's iteration order does not depend on
|
||||
// insertion history), so a plain per-key diff is correct
|
||||
// and minimal, as before
|
||||
common_keys = std::move(common_keys_source_order);
|
||||
return true;
|
||||
}
|
||||
|
||||
// slow path: the common keys are in a different relative
|
||||
// order in source and target (only possible for a
|
||||
// reorderable object_t like ordered_map). Building a
|
||||
// minimal reordering patch is a nontrivial (LCS-like)
|
||||
// problem; instead, remove every source key -- both
|
||||
// deleted keys (which must be removed regardless) and
|
||||
// common keys (removed so they can be re-added in
|
||||
// target's order) -- and re-add every key that should
|
||||
// remain, with its final target value, in target's
|
||||
// order. basic_json::patch()'s "add" operation on an
|
||||
// object uses operator[], which appends at the end for a
|
||||
// vector-backed insertion-ordered map when the key does
|
||||
// not already exist -- so removing a key and then adding
|
||||
// it moves it to the end, fixing its position.
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
diff_remove(result, detail::concat<string_t>(path, '/', detail::escape(it.key())));
|
||||
}
|
||||
|
||||
// add every key that is either common (just removed
|
||||
// above) or brand new, in target's iteration order, so
|
||||
// that the final order after applying the patch matches
|
||||
// target exactly
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
diff_add(result, detail::concat<string_t>(path, '/', detail::escape(it.key())), it.value());
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/*!
|
||||
@brief @ref diff, for values at nesting level @a depth, appending the
|
||||
operations to @a result
|
||||
|
||||
Diffing two arrays or objects calls this function again, once per nesting
|
||||
level, so values nested deeply enough used to exhaust the call stack and
|
||||
terminate the process. The descent is bounded here: once @ref
|
||||
detail::recursion_depth_limit levels have been entered, @ref
|
||||
diff_iteratively diffs what is left without the call stack.
|
||||
*/
|
||||
static void diff_recursively(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path, const std::size_t depth)
|
||||
{
|
||||
// if the values are the same, there is nothing to do
|
||||
// if the values are the same, return an empty patch
|
||||
if (source == target)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
if (JSON_HEDLEY_UNLIKELY(depth >= detail::recursion_depth_limit()))
|
||||
{
|
||||
diff_iteratively(result, source, target, path);
|
||||
return;
|
||||
return result;
|
||||
}
|
||||
|
||||
if (source.type() != target.type())
|
||||
{
|
||||
// different types: replace value
|
||||
diff_replace(result, path, target);
|
||||
return;
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "replace"}, {"path", path}, {"value", target}
|
||||
});
|
||||
return result;
|
||||
}
|
||||
|
||||
switch (source.type())
|
||||
@@ -6306,50 +6087,185 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
|
||||
while (i < source.size() && i < target.size())
|
||||
{
|
||||
// recursive call to compare array values at index i
|
||||
diff_recursively(result, source[i], target[i], detail::concat<string_t>(path, '/', detail::to_string<string_t>(i)), depth + 1);
|
||||
auto temp_diff = diff(source[i], target[i], detail::concat<string_t>(path, '/', detail::to_string<string_t>(i)));
|
||||
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
|
||||
++i;
|
||||
}
|
||||
|
||||
// We now reached the end of at least one array
|
||||
// in a second pass, traverse the remaining elements
|
||||
diff_array_tails(result, source, target, path, i);
|
||||
|
||||
// remove my remaining elements, highest index first; appending
|
||||
// in that order avoids the quadratic reinsertion done before
|
||||
for (std::size_t j = source.size(); j > i; --j)
|
||||
{
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"},
|
||||
{"path", detail::concat<string_t>(path, '/', detail::to_string<string_t>(j - 1))}
|
||||
}));
|
||||
}
|
||||
i = source.size();
|
||||
|
||||
// add other remaining elements
|
||||
while (i < target.size())
|
||||
{
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "add"},
|
||||
{"path", detail::concat<string_t>(path, "/-")},
|
||||
{"value", target[i]}
|
||||
});
|
||||
++i;
|
||||
}
|
||||
|
||||
break;
|
||||
}
|
||||
|
||||
case value_t::object:
|
||||
{
|
||||
std::vector<typename object_t::key_type> common_keys;
|
||||
basic_json added_ops(value_t::array);
|
||||
if (diff_object_keys(result, source, target, path, common_keys, added_ops))
|
||||
// first pass: record, for every source key, whether it is
|
||||
// common to both objects (in source's iteration order) or
|
||||
// was deleted (i.e., in source but not in target) -- this is
|
||||
// a by-product of the target.find() call already needed to
|
||||
// tell the two cases apart, so it adds no extra lookups. The
|
||||
// "remove" ops themselves are emitted later, interleaved
|
||||
// with the recursive per-key diffs in the fast path below,
|
||||
// to match source's original iteration order (as the
|
||||
// original, pre-reordering-aware implementation did) instead
|
||||
// of grouping all removes before all recursive diffs.
|
||||
std::vector<typename object_t::key_type> common_keys_source_order;
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
// fast path: common_keys is, by construction, the
|
||||
// subsequence of source's keys that are common to both
|
||||
// objects, in source's iteration order -- so it can be
|
||||
// walked in lockstep with `source` using a cheap key
|
||||
// comparison instead of another lookup. Deleted keys
|
||||
// (those source keys not in common_keys) are interleaved
|
||||
// here too, in source's original order, to match the
|
||||
// historical (pre-reordering-aware) output order.
|
||||
auto common_it = common_keys.cbegin();
|
||||
if (target.find(it.key()) != target.end())
|
||||
{
|
||||
common_keys_source_order.push_back(it.key());
|
||||
}
|
||||
}
|
||||
|
||||
// second pass: find keys that were added (i.e., in target but
|
||||
// not in source), and record the keys common to both, in
|
||||
// target's iteration order -- again a by-product of the
|
||||
// source.find() call already needed to detect added keys. At
|
||||
// the same time, determine whether every added key comes
|
||||
// after every common key in target's order (a precondition
|
||||
// for the fast path below, which only ever appends new keys
|
||||
// at the very end): for an object_t whose iteration order is
|
||||
// a pure function of the key set (e.g. the default std::map,
|
||||
// which always iterates in sorted key order), the order
|
||||
// check further below is always true and this whole
|
||||
// mechanism is effectively a no-op; it only matters for a
|
||||
// reorderable object_t such as the one backing `ordered_json`.
|
||||
// patch ops for keys that were added (i.e., in target but not
|
||||
// in source); built here so the fast path below can reuse
|
||||
// them without a second source.find() per target key. Only
|
||||
// used by the fast path -- the slow (reordering) path
|
||||
// rebuilds "add" ops for every key itself.
|
||||
std::vector<typename object_t::key_type> common_keys_target_order;
|
||||
basic_json added_ops(value_t::array);
|
||||
bool new_keys_form_suffix = true;
|
||||
bool seen_new_key = false;
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
if (source.find(it.key()) == source.end())
|
||||
{
|
||||
seen_new_key = true;
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
added_ops.push_back(
|
||||
{
|
||||
{"op", "add"}, {"path", path_key},
|
||||
{"value", it.value()}
|
||||
});
|
||||
}
|
||||
else
|
||||
{
|
||||
common_keys_target_order.push_back(it.key());
|
||||
if (seen_new_key)
|
||||
{
|
||||
new_keys_form_suffix = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
|
||||
{
|
||||
// fast path: order of common keys already matches (or the
|
||||
// object_t's iteration order does not depend on
|
||||
// insertion history), so a plain per-key recursive diff
|
||||
// is correct and minimal, as before. common_keys_source_order
|
||||
// is, by construction, the subsequence of source's keys
|
||||
// that are common to both objects, in source's iteration
|
||||
// order -- so it can be walked in lockstep with `source`
|
||||
// using a cheap key comparison instead of another lookup.
|
||||
// Deleted keys (those source keys not in common_keys_source_order)
|
||||
// are interleaved here too, in source's original order, to
|
||||
// match the historical (pre-reordering-aware) output order.
|
||||
auto common_it = common_keys_source_order.cbegin();
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
if (common_it != common_keys.cend() && it.key() == *common_it)
|
||||
if (common_it != common_keys_source_order.cend() && it.key() == *common_it)
|
||||
{
|
||||
diff_recursively(result, it.value(), target[it.key()], detail::concat<string_t>(path, '/', detail::escape(it.key())), depth + 1);
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
auto temp_diff = diff(it.value(), target[it.key()], path_key);
|
||||
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
|
||||
++common_it;
|
||||
}
|
||||
else
|
||||
{
|
||||
// found a key that is not in target -> remove it
|
||||
diff_remove(result, detail::concat<string_t>(path, '/', detail::escape(it.key())));
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"}, {"path", path_key}
|
||||
}));
|
||||
}
|
||||
}
|
||||
|
||||
// append the "add" ops for brand-new keys collected by
|
||||
// diff_object_keys -- no second source.find() per target
|
||||
// key needed
|
||||
// append the "add" ops for brand-new keys collected above
|
||||
// during the pass over target -- no second source.find()
|
||||
// per target key needed
|
||||
result.insert(result.end(), added_ops.begin(), added_ops.end());
|
||||
}
|
||||
else
|
||||
{
|
||||
// slow path: the common keys are in a different relative
|
||||
// order in source and target (only possible for a
|
||||
// reorderable object_t like ordered_map). Building a
|
||||
// minimal reordering patch is a nontrivial (LCS-like)
|
||||
// problem; instead, remove every source key -- both
|
||||
// deleted keys (which must be removed regardless) and
|
||||
// common keys (removed so they can be re-added in
|
||||
// target's order) -- and re-add every key that should
|
||||
// remain, with its final target value, in target's
|
||||
// order. basic_json::patch()'s "add" operation on an
|
||||
// object uses operator[], which appends at the end for a
|
||||
// vector-backed insertion-ordered map when the key does
|
||||
// not already exist -- so removing a key and then adding
|
||||
// it moves it to the end, fixing its position.
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"}, {"path", path_key}
|
||||
}));
|
||||
}
|
||||
|
||||
// add every key that is either common (just removed
|
||||
// above) or brand new, in target's iteration order, so
|
||||
// that the final order after applying the patch matches
|
||||
// target exactly
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "add"}, {"path", path_key},
|
||||
{"value", it.value()}
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
break;
|
||||
}
|
||||
|
||||
@@ -6364,170 +6280,16 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
|
||||
default:
|
||||
{
|
||||
// both primitive types: replace value
|
||||
diff_replace(result, path, target);
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "replace"}, {"path", path}, {"value", target}
|
||||
});
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/*!
|
||||
@brief @ref diff without the call stack, appending the operations to
|
||||
@a result
|
||||
|
||||
Produces the same operations as @ref diff_recursively. Only reached for
|
||||
values nested more deeply than @ref detail::recursion_depth_limit.
|
||||
*/
|
||||
static void diff_iteratively(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path)
|
||||
{
|
||||
// The arrays and objects being diffed are kept on an explicit stack,
|
||||
// and every pair of elements is still diffed completely before the
|
||||
// next one, so the operations come out in the same order as in
|
||||
// diff_recursively. The path of the values being diffed is kept in
|
||||
// one buffer that grows and shrinks with the stack, rather than in a
|
||||
// new string per level.
|
||||
std::vector<diff_frame> stack;
|
||||
string_t current_path = path;
|
||||
|
||||
// diff `s` against `t`, whose path is current_path: primitives,
|
||||
// values of different types, and objects whose members were reordered
|
||||
// are handled right away; arrays and other objects get a frame
|
||||
const auto enter = [&result, &stack, ¤t_path](const basic_json & s, const basic_json & t)
|
||||
{
|
||||
// if the values are the same, there is nothing to do. Arrays and
|
||||
// objects are not compared up front: comparing them visits
|
||||
// everything below them, so doing that at every level would take
|
||||
// quadratic time in the nesting depth - equal ones yield no
|
||||
// operations anyway.
|
||||
if ((!s.is_structured() || !t.is_structured()) && s == t)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
if (s.type() != t.type())
|
||||
{
|
||||
// different types: replace value
|
||||
diff_replace(result, current_path, t);
|
||||
return;
|
||||
}
|
||||
|
||||
switch (s.type())
|
||||
{
|
||||
case value_t::array:
|
||||
{
|
||||
stack.emplace_back(&s, &t, current_path.size());
|
||||
return;
|
||||
}
|
||||
|
||||
case value_t::object:
|
||||
{
|
||||
std::vector<typename object_t::key_type> common_keys;
|
||||
basic_json added_ops(value_t::array);
|
||||
if (diff_object_keys(result, s, t, current_path, common_keys, added_ops))
|
||||
{
|
||||
// fast path: the frame walks source in lockstep with
|
||||
// common_keys, as diff_recursively does, and appends
|
||||
// added_ops once all members are done
|
||||
stack.emplace_back(&s, &t, current_path.size());
|
||||
stack.back().member = s.cbegin();
|
||||
stack.back().common_keys = std::move(common_keys);
|
||||
stack.back().added_ops = std::move(added_ops);
|
||||
}
|
||||
return;
|
||||
}
|
||||
|
||||
case value_t::null:
|
||||
case value_t::string:
|
||||
case value_t::boolean:
|
||||
case value_t::number_integer:
|
||||
case value_t::number_unsigned:
|
||||
case value_t::number_float:
|
||||
case value_t::binary:
|
||||
case value_t::discarded:
|
||||
default:
|
||||
{
|
||||
// both primitive types: replace value
|
||||
diff_replace(result, current_path, t);
|
||||
return;
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
enter(source, target);
|
||||
while (!stack.empty())
|
||||
{
|
||||
// the frame is copied out member by member and changed through
|
||||
// stack.back(): enter() may push a frame and the end of the loop
|
||||
// pops it, either of which would invalidate a reference to it
|
||||
const basic_json* const s = stack.back().source;
|
||||
const basic_json* const t = stack.back().target;
|
||||
const std::size_t path_length = stack.back().path_length;
|
||||
const std::size_t depth = stack.size();
|
||||
|
||||
if (s->is_array())
|
||||
{
|
||||
const auto& source_array = *s->m_data.m_value.array;
|
||||
const auto& target_array = *t->m_data.m_value.array;
|
||||
|
||||
// first pass: traverse common elements
|
||||
const std::size_t i = stack.back().index;
|
||||
if (i < source_array.size() && i < target_array.size())
|
||||
{
|
||||
++stack.back().index;
|
||||
detail::concat_into(current_path, '/', detail::to_string<string_t>(i));
|
||||
enter(source_array[i], target_array[i]);
|
||||
if (stack.size() == depth)
|
||||
{
|
||||
current_path.resize(path_length);
|
||||
}
|
||||
continue;
|
||||
}
|
||||
|
||||
// We now reached the end of at least one array
|
||||
// in a second pass, traverse the remaining elements
|
||||
diff_array_tails(result, *s, *t, current_path, i);
|
||||
}
|
||||
else
|
||||
{
|
||||
const const_iterator it = stack.back().member;
|
||||
if (it != s->cend())
|
||||
{
|
||||
++stack.back().member;
|
||||
const std::size_t next_common = stack.back().next_common;
|
||||
if (next_common < stack.back().common_keys.size() && it.key() == stack.back().common_keys[next_common])
|
||||
{
|
||||
++stack.back().next_common;
|
||||
const basic_json& target_value = (*t)[it.key()];
|
||||
detail::concat_into(current_path, '/', detail::escape(it.key()));
|
||||
enter(it.value(), target_value);
|
||||
if (stack.size() == depth)
|
||||
{
|
||||
current_path.resize(path_length);
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
// found a key that is not in target -> remove it
|
||||
diff_remove(result, detail::concat<string_t>(current_path, '/', detail::escape(it.key())));
|
||||
}
|
||||
continue;
|
||||
}
|
||||
|
||||
// append the "add" ops for brand-new keys collected when the
|
||||
// object was entered
|
||||
result.insert(result.end(), stack.back().added_ops.begin(), stack.back().added_ops.end());
|
||||
}
|
||||
|
||||
// this array or object is done: continue with the one it is in
|
||||
stack.pop_back();
|
||||
if (!stack.empty())
|
||||
{
|
||||
current_path.resize(stack.back().path_length);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
public:
|
||||
/// @}
|
||||
|
||||
////////////////////////////////
|
||||
|
||||
+168
-406
@@ -31944,240 +31944,21 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
|
||||
{
|
||||
// the patch
|
||||
basic_json result(value_t::array);
|
||||
diff_recursively(result, source, target, path, 0);
|
||||
return result;
|
||||
}
|
||||
|
||||
private:
|
||||
/// @brief two arrays or two objects @ref diff_iteratively is diffing
|
||||
struct diff_frame
|
||||
{
|
||||
diff_frame(const basic_json* source_, const basic_json* target_, const std::size_t path_length_) noexcept
|
||||
: source(source_), target(target_), path_length(path_length_)
|
||||
{}
|
||||
|
||||
// declared for GCC's -Weffc++, which asks for them in a class with
|
||||
// pointer members and a non-trivial destructor; the exception
|
||||
// specifications are left implicit, as GCC 4.8 rejects explicit ones
|
||||
// that differ from them
|
||||
diff_frame(const diff_frame&) = default;
|
||||
diff_frame(diff_frame&&) = default;
|
||||
diff_frame& operator=(const diff_frame&) = default;
|
||||
diff_frame& operator=(diff_frame&&) = default;
|
||||
~diff_frame() = default;
|
||||
|
||||
/// the values being diffed, both arrays or both objects
|
||||
const basic_json* source;
|
||||
const basic_json* target;
|
||||
/// the length of their path in `current_path`
|
||||
std::size_t path_length;
|
||||
/// arrays: the next index to diff
|
||||
std::size_t index = 0;
|
||||
/// objects: the next member of source to look at
|
||||
const_iterator member{}; // NOLINT(readability-redundant-member-init)
|
||||
/// objects: the keys common to both, in source's order
|
||||
std::vector<typename object_t::key_type> common_keys{}; // NOLINT(readability-redundant-member-init)
|
||||
/// objects: the next entry of common_keys
|
||||
std::size_t next_common = 0;
|
||||
/// objects: the "add" operations for keys only target has
|
||||
basic_json added_ops{}; // NOLINT(readability-redundant-member-init)
|
||||
};
|
||||
|
||||
// The operations of a diff are built by the functions below rather than
|
||||
// where they are needed: building one takes several temporaries, and
|
||||
// unoptimized builds give each temporary a stack slot of its own in the
|
||||
// function it appears in. In diff_recursively, which is on the call stack
|
||||
// once per nesting level, that made every level cost kilobytes of stack.
|
||||
|
||||
/// @brief append a "replace" operation for @a path with @a value to @a result
|
||||
static void diff_replace(basic_json& result, const string_t& path, const basic_json& value)
|
||||
{
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "replace"}, {"path", path}, {"value", value}
|
||||
});
|
||||
}
|
||||
|
||||
/// @brief append a "remove" operation for @a path to @a result
|
||||
static void diff_remove(basic_json& result, const string_t& path)
|
||||
{
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"}, {"path", path}
|
||||
}));
|
||||
}
|
||||
|
||||
/// @brief append an "add" operation for @a path with @a value to @a result
|
||||
static void diff_add(basic_json& result, const string_t& path, const basic_json& value)
|
||||
{
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "add"}, {"path", path}, {"value", value}
|
||||
});
|
||||
}
|
||||
|
||||
/// @brief append the "remove" operations for the elements of array
|
||||
/// @a source from @a index on, and the "add" operations for the
|
||||
/// elements of array @a target from source's size on, to @a result
|
||||
static void diff_array_tails(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path, const std::size_t index)
|
||||
{
|
||||
// remove my remaining elements, highest index first; appending
|
||||
// in that order avoids the quadratic reinsertion done before
|
||||
for (std::size_t j = source.size(); j > index; --j)
|
||||
{
|
||||
diff_remove(result, detail::concat<string_t>(path, '/', detail::to_string<string_t>(j - 1)));
|
||||
}
|
||||
|
||||
// add other remaining elements
|
||||
for (std::size_t i = source.size(); i < target.size(); ++i)
|
||||
{
|
||||
diff_add(result, detail::concat<string_t>(path, "/-"), target[i]);
|
||||
}
|
||||
}
|
||||
|
||||
/*!
|
||||
@brief compare the keys of objects @a source and @a target
|
||||
|
||||
If the keys both objects have are in the same order in both, and the keys
|
||||
only @a target has come after them, stores the keys common to both in
|
||||
source's order in @a common_keys, stores the "add" operations for the keys
|
||||
only @a target has in @a added_ops, and returns true: the caller then diffs
|
||||
the objects member by member. Otherwise, appends operations that remove
|
||||
every member of @a source and add every member of @a target to @a result,
|
||||
and returns false.
|
||||
*/
|
||||
static bool diff_object_keys(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path, std::vector<typename object_t::key_type>& common_keys,
|
||||
basic_json& added_ops)
|
||||
{
|
||||
// first pass: record, for every source key, whether it is
|
||||
// common to both objects (in source's iteration order) or
|
||||
// was deleted (i.e., in source but not in target) -- this is
|
||||
// a by-product of the target.find() call already needed to
|
||||
// tell the two cases apart, so it adds no extra lookups. The
|
||||
// "remove" ops themselves are emitted later, interleaved
|
||||
// with the per-key diffs in the caller's fast path, to match
|
||||
// source's original iteration order (as the original,
|
||||
// pre-reordering-aware implementation did) instead of
|
||||
// grouping all removes before all per-key diffs.
|
||||
std::vector<typename object_t::key_type> common_keys_source_order;
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
if (target.find(it.key()) != target.end())
|
||||
{
|
||||
common_keys_source_order.push_back(it.key());
|
||||
}
|
||||
}
|
||||
|
||||
// second pass: find keys that were added (i.e., in target but
|
||||
// not in source), and record the keys common to both, in
|
||||
// target's iteration order -- again a by-product of the
|
||||
// source.find() call already needed to detect added keys. At
|
||||
// the same time, determine whether every added key comes
|
||||
// after every common key in target's order (a precondition
|
||||
// for the fast path, which only ever appends new keys
|
||||
// at the very end): for an object_t whose iteration order is
|
||||
// a pure function of the key set (e.g. the default std::map,
|
||||
// which always iterates in sorted key order), the order
|
||||
// check further below is always true and this whole
|
||||
// mechanism is effectively a no-op; it only matters for a
|
||||
// reorderable object_t such as the one backing `ordered_json`.
|
||||
// The patch ops for keys that were added (i.e., in target but not
|
||||
// in source) are built here so the fast path can reuse
|
||||
// them without a second source.find() per target key. Only
|
||||
// used by the fast path -- the slow (reordering) path
|
||||
// rebuilds "add" ops for every key itself.
|
||||
std::vector<typename object_t::key_type> common_keys_target_order;
|
||||
bool new_keys_form_suffix = true;
|
||||
bool seen_new_key = false;
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
if (source.find(it.key()) == source.end())
|
||||
{
|
||||
seen_new_key = true;
|
||||
diff_add(added_ops, detail::concat<string_t>(path, '/', detail::escape(it.key())), it.value());
|
||||
}
|
||||
else
|
||||
{
|
||||
common_keys_target_order.push_back(it.key());
|
||||
if (seen_new_key)
|
||||
{
|
||||
new_keys_form_suffix = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
|
||||
{
|
||||
// fast path: order of common keys already matches (or the
|
||||
// object_t's iteration order does not depend on
|
||||
// insertion history), so a plain per-key diff is correct
|
||||
// and minimal, as before
|
||||
common_keys = std::move(common_keys_source_order);
|
||||
return true;
|
||||
}
|
||||
|
||||
// slow path: the common keys are in a different relative
|
||||
// order in source and target (only possible for a
|
||||
// reorderable object_t like ordered_map). Building a
|
||||
// minimal reordering patch is a nontrivial (LCS-like)
|
||||
// problem; instead, remove every source key -- both
|
||||
// deleted keys (which must be removed regardless) and
|
||||
// common keys (removed so they can be re-added in
|
||||
// target's order) -- and re-add every key that should
|
||||
// remain, with its final target value, in target's
|
||||
// order. basic_json::patch()'s "add" operation on an
|
||||
// object uses operator[], which appends at the end for a
|
||||
// vector-backed insertion-ordered map when the key does
|
||||
// not already exist -- so removing a key and then adding
|
||||
// it moves it to the end, fixing its position.
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
diff_remove(result, detail::concat<string_t>(path, '/', detail::escape(it.key())));
|
||||
}
|
||||
|
||||
// add every key that is either common (just removed
|
||||
// above) or brand new, in target's iteration order, so
|
||||
// that the final order after applying the patch matches
|
||||
// target exactly
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
diff_add(result, detail::concat<string_t>(path, '/', detail::escape(it.key())), it.value());
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/*!
|
||||
@brief @ref diff, for values at nesting level @a depth, appending the
|
||||
operations to @a result
|
||||
|
||||
Diffing two arrays or objects calls this function again, once per nesting
|
||||
level, so values nested deeply enough used to exhaust the call stack and
|
||||
terminate the process. The descent is bounded here: once @ref
|
||||
detail::recursion_depth_limit levels have been entered, @ref
|
||||
diff_iteratively diffs what is left without the call stack.
|
||||
*/
|
||||
static void diff_recursively(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path, const std::size_t depth)
|
||||
{
|
||||
// if the values are the same, there is nothing to do
|
||||
// if the values are the same, return an empty patch
|
||||
if (source == target)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
if (JSON_HEDLEY_UNLIKELY(depth >= detail::recursion_depth_limit()))
|
||||
{
|
||||
diff_iteratively(result, source, target, path);
|
||||
return;
|
||||
return result;
|
||||
}
|
||||
|
||||
if (source.type() != target.type())
|
||||
{
|
||||
// different types: replace value
|
||||
diff_replace(result, path, target);
|
||||
return;
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "replace"}, {"path", path}, {"value", target}
|
||||
});
|
||||
return result;
|
||||
}
|
||||
|
||||
switch (source.type())
|
||||
@@ -32189,50 +31970,185 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
|
||||
while (i < source.size() && i < target.size())
|
||||
{
|
||||
// recursive call to compare array values at index i
|
||||
diff_recursively(result, source[i], target[i], detail::concat<string_t>(path, '/', detail::to_string<string_t>(i)), depth + 1);
|
||||
auto temp_diff = diff(source[i], target[i], detail::concat<string_t>(path, '/', detail::to_string<string_t>(i)));
|
||||
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
|
||||
++i;
|
||||
}
|
||||
|
||||
// We now reached the end of at least one array
|
||||
// in a second pass, traverse the remaining elements
|
||||
diff_array_tails(result, source, target, path, i);
|
||||
|
||||
// remove my remaining elements, highest index first; appending
|
||||
// in that order avoids the quadratic reinsertion done before
|
||||
for (std::size_t j = source.size(); j > i; --j)
|
||||
{
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"},
|
||||
{"path", detail::concat<string_t>(path, '/', detail::to_string<string_t>(j - 1))}
|
||||
}));
|
||||
}
|
||||
i = source.size();
|
||||
|
||||
// add other remaining elements
|
||||
while (i < target.size())
|
||||
{
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "add"},
|
||||
{"path", detail::concat<string_t>(path, "/-")},
|
||||
{"value", target[i]}
|
||||
});
|
||||
++i;
|
||||
}
|
||||
|
||||
break;
|
||||
}
|
||||
|
||||
case value_t::object:
|
||||
{
|
||||
std::vector<typename object_t::key_type> common_keys;
|
||||
basic_json added_ops(value_t::array);
|
||||
if (diff_object_keys(result, source, target, path, common_keys, added_ops))
|
||||
// first pass: record, for every source key, whether it is
|
||||
// common to both objects (in source's iteration order) or
|
||||
// was deleted (i.e., in source but not in target) -- this is
|
||||
// a by-product of the target.find() call already needed to
|
||||
// tell the two cases apart, so it adds no extra lookups. The
|
||||
// "remove" ops themselves are emitted later, interleaved
|
||||
// with the recursive per-key diffs in the fast path below,
|
||||
// to match source's original iteration order (as the
|
||||
// original, pre-reordering-aware implementation did) instead
|
||||
// of grouping all removes before all recursive diffs.
|
||||
std::vector<typename object_t::key_type> common_keys_source_order;
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
// fast path: common_keys is, by construction, the
|
||||
// subsequence of source's keys that are common to both
|
||||
// objects, in source's iteration order -- so it can be
|
||||
// walked in lockstep with `source` using a cheap key
|
||||
// comparison instead of another lookup. Deleted keys
|
||||
// (those source keys not in common_keys) are interleaved
|
||||
// here too, in source's original order, to match the
|
||||
// historical (pre-reordering-aware) output order.
|
||||
auto common_it = common_keys.cbegin();
|
||||
if (target.find(it.key()) != target.end())
|
||||
{
|
||||
common_keys_source_order.push_back(it.key());
|
||||
}
|
||||
}
|
||||
|
||||
// second pass: find keys that were added (i.e., in target but
|
||||
// not in source), and record the keys common to both, in
|
||||
// target's iteration order -- again a by-product of the
|
||||
// source.find() call already needed to detect added keys. At
|
||||
// the same time, determine whether every added key comes
|
||||
// after every common key in target's order (a precondition
|
||||
// for the fast path below, which only ever appends new keys
|
||||
// at the very end): for an object_t whose iteration order is
|
||||
// a pure function of the key set (e.g. the default std::map,
|
||||
// which always iterates in sorted key order), the order
|
||||
// check further below is always true and this whole
|
||||
// mechanism is effectively a no-op; it only matters for a
|
||||
// reorderable object_t such as the one backing `ordered_json`.
|
||||
// patch ops for keys that were added (i.e., in target but not
|
||||
// in source); built here so the fast path below can reuse
|
||||
// them without a second source.find() per target key. Only
|
||||
// used by the fast path -- the slow (reordering) path
|
||||
// rebuilds "add" ops for every key itself.
|
||||
std::vector<typename object_t::key_type> common_keys_target_order;
|
||||
basic_json added_ops(value_t::array);
|
||||
bool new_keys_form_suffix = true;
|
||||
bool seen_new_key = false;
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
if (source.find(it.key()) == source.end())
|
||||
{
|
||||
seen_new_key = true;
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
added_ops.push_back(
|
||||
{
|
||||
{"op", "add"}, {"path", path_key},
|
||||
{"value", it.value()}
|
||||
});
|
||||
}
|
||||
else
|
||||
{
|
||||
common_keys_target_order.push_back(it.key());
|
||||
if (seen_new_key)
|
||||
{
|
||||
new_keys_form_suffix = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
|
||||
{
|
||||
// fast path: order of common keys already matches (or the
|
||||
// object_t's iteration order does not depend on
|
||||
// insertion history), so a plain per-key recursive diff
|
||||
// is correct and minimal, as before. common_keys_source_order
|
||||
// is, by construction, the subsequence of source's keys
|
||||
// that are common to both objects, in source's iteration
|
||||
// order -- so it can be walked in lockstep with `source`
|
||||
// using a cheap key comparison instead of another lookup.
|
||||
// Deleted keys (those source keys not in common_keys_source_order)
|
||||
// are interleaved here too, in source's original order, to
|
||||
// match the historical (pre-reordering-aware) output order.
|
||||
auto common_it = common_keys_source_order.cbegin();
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
if (common_it != common_keys.cend() && it.key() == *common_it)
|
||||
if (common_it != common_keys_source_order.cend() && it.key() == *common_it)
|
||||
{
|
||||
diff_recursively(result, it.value(), target[it.key()], detail::concat<string_t>(path, '/', detail::escape(it.key())), depth + 1);
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
auto temp_diff = diff(it.value(), target[it.key()], path_key);
|
||||
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
|
||||
++common_it;
|
||||
}
|
||||
else
|
||||
{
|
||||
// found a key that is not in target -> remove it
|
||||
diff_remove(result, detail::concat<string_t>(path, '/', detail::escape(it.key())));
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"}, {"path", path_key}
|
||||
}));
|
||||
}
|
||||
}
|
||||
|
||||
// append the "add" ops for brand-new keys collected by
|
||||
// diff_object_keys -- no second source.find() per target
|
||||
// key needed
|
||||
// append the "add" ops for brand-new keys collected above
|
||||
// during the pass over target -- no second source.find()
|
||||
// per target key needed
|
||||
result.insert(result.end(), added_ops.begin(), added_ops.end());
|
||||
}
|
||||
else
|
||||
{
|
||||
// slow path: the common keys are in a different relative
|
||||
// order in source and target (only possible for a
|
||||
// reorderable object_t like ordered_map). Building a
|
||||
// minimal reordering patch is a nontrivial (LCS-like)
|
||||
// problem; instead, remove every source key -- both
|
||||
// deleted keys (which must be removed regardless) and
|
||||
// common keys (removed so they can be re-added in
|
||||
// target's order) -- and re-add every key that should
|
||||
// remain, with its final target value, in target's
|
||||
// order. basic_json::patch()'s "add" operation on an
|
||||
// object uses operator[], which appends at the end for a
|
||||
// vector-backed insertion-ordered map when the key does
|
||||
// not already exist -- so removing a key and then adding
|
||||
// it moves it to the end, fixing its position.
|
||||
for (auto it = source.cbegin(); it != source.cend(); ++it)
|
||||
{
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(object(
|
||||
{
|
||||
{"op", "remove"}, {"path", path_key}
|
||||
}));
|
||||
}
|
||||
|
||||
// add every key that is either common (just removed
|
||||
// above) or brand new, in target's iteration order, so
|
||||
// that the final order after applying the patch matches
|
||||
// target exactly
|
||||
for (auto it = target.cbegin(); it != target.cend(); ++it)
|
||||
{
|
||||
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "add"}, {"path", path_key},
|
||||
{"value", it.value()}
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
break;
|
||||
}
|
||||
|
||||
@@ -32247,170 +32163,16 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
|
||||
default:
|
||||
{
|
||||
// both primitive types: replace value
|
||||
diff_replace(result, path, target);
|
||||
result.push_back(
|
||||
{
|
||||
{"op", "replace"}, {"path", path}, {"value", target}
|
||||
});
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/*!
|
||||
@brief @ref diff without the call stack, appending the operations to
|
||||
@a result
|
||||
|
||||
Produces the same operations as @ref diff_recursively. Only reached for
|
||||
values nested more deeply than @ref detail::recursion_depth_limit.
|
||||
*/
|
||||
static void diff_iteratively(basic_json& result, const basic_json& source, const basic_json& target,
|
||||
const string_t& path)
|
||||
{
|
||||
// The arrays and objects being diffed are kept on an explicit stack,
|
||||
// and every pair of elements is still diffed completely before the
|
||||
// next one, so the operations come out in the same order as in
|
||||
// diff_recursively. The path of the values being diffed is kept in
|
||||
// one buffer that grows and shrinks with the stack, rather than in a
|
||||
// new string per level.
|
||||
std::vector<diff_frame> stack;
|
||||
string_t current_path = path;
|
||||
|
||||
// diff `s` against `t`, whose path is current_path: primitives,
|
||||
// values of different types, and objects whose members were reordered
|
||||
// are handled right away; arrays and other objects get a frame
|
||||
const auto enter = [&result, &stack, ¤t_path](const basic_json & s, const basic_json & t)
|
||||
{
|
||||
// if the values are the same, there is nothing to do. Arrays and
|
||||
// objects are not compared up front: comparing them visits
|
||||
// everything below them, so doing that at every level would take
|
||||
// quadratic time in the nesting depth - equal ones yield no
|
||||
// operations anyway.
|
||||
if ((!s.is_structured() || !t.is_structured()) && s == t)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
if (s.type() != t.type())
|
||||
{
|
||||
// different types: replace value
|
||||
diff_replace(result, current_path, t);
|
||||
return;
|
||||
}
|
||||
|
||||
switch (s.type())
|
||||
{
|
||||
case value_t::array:
|
||||
{
|
||||
stack.emplace_back(&s, &t, current_path.size());
|
||||
return;
|
||||
}
|
||||
|
||||
case value_t::object:
|
||||
{
|
||||
std::vector<typename object_t::key_type> common_keys;
|
||||
basic_json added_ops(value_t::array);
|
||||
if (diff_object_keys(result, s, t, current_path, common_keys, added_ops))
|
||||
{
|
||||
// fast path: the frame walks source in lockstep with
|
||||
// common_keys, as diff_recursively does, and appends
|
||||
// added_ops once all members are done
|
||||
stack.emplace_back(&s, &t, current_path.size());
|
||||
stack.back().member = s.cbegin();
|
||||
stack.back().common_keys = std::move(common_keys);
|
||||
stack.back().added_ops = std::move(added_ops);
|
||||
}
|
||||
return;
|
||||
}
|
||||
|
||||
case value_t::null:
|
||||
case value_t::string:
|
||||
case value_t::boolean:
|
||||
case value_t::number_integer:
|
||||
case value_t::number_unsigned:
|
||||
case value_t::number_float:
|
||||
case value_t::binary:
|
||||
case value_t::discarded:
|
||||
default:
|
||||
{
|
||||
// both primitive types: replace value
|
||||
diff_replace(result, current_path, t);
|
||||
return;
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
enter(source, target);
|
||||
while (!stack.empty())
|
||||
{
|
||||
// the frame is copied out member by member and changed through
|
||||
// stack.back(): enter() may push a frame and the end of the loop
|
||||
// pops it, either of which would invalidate a reference to it
|
||||
const basic_json* const s = stack.back().source;
|
||||
const basic_json* const t = stack.back().target;
|
||||
const std::size_t path_length = stack.back().path_length;
|
||||
const std::size_t depth = stack.size();
|
||||
|
||||
if (s->is_array())
|
||||
{
|
||||
const auto& source_array = *s->m_data.m_value.array;
|
||||
const auto& target_array = *t->m_data.m_value.array;
|
||||
|
||||
// first pass: traverse common elements
|
||||
const std::size_t i = stack.back().index;
|
||||
if (i < source_array.size() && i < target_array.size())
|
||||
{
|
||||
++stack.back().index;
|
||||
detail::concat_into(current_path, '/', detail::to_string<string_t>(i));
|
||||
enter(source_array[i], target_array[i]);
|
||||
if (stack.size() == depth)
|
||||
{
|
||||
current_path.resize(path_length);
|
||||
}
|
||||
continue;
|
||||
}
|
||||
|
||||
// We now reached the end of at least one array
|
||||
// in a second pass, traverse the remaining elements
|
||||
diff_array_tails(result, *s, *t, current_path, i);
|
||||
}
|
||||
else
|
||||
{
|
||||
const const_iterator it = stack.back().member;
|
||||
if (it != s->cend())
|
||||
{
|
||||
++stack.back().member;
|
||||
const std::size_t next_common = stack.back().next_common;
|
||||
if (next_common < stack.back().common_keys.size() && it.key() == stack.back().common_keys[next_common])
|
||||
{
|
||||
++stack.back().next_common;
|
||||
const basic_json& target_value = (*t)[it.key()];
|
||||
detail::concat_into(current_path, '/', detail::escape(it.key()));
|
||||
enter(it.value(), target_value);
|
||||
if (stack.size() == depth)
|
||||
{
|
||||
current_path.resize(path_length);
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
// found a key that is not in target -> remove it
|
||||
diff_remove(result, detail::concat<string_t>(current_path, '/', detail::escape(it.key())));
|
||||
}
|
||||
continue;
|
||||
}
|
||||
|
||||
// append the "add" ops for brand-new keys collected when the
|
||||
// object was entered
|
||||
result.insert(result.end(), stack.back().added_ops.begin(), stack.back().added_ops.end());
|
||||
}
|
||||
|
||||
// this array or object is done: continue with the one it is in
|
||||
stack.pop_back();
|
||||
if (!stack.empty())
|
||||
{
|
||||
current_path.resize(stack.back().path_length);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
public:
|
||||
/// @}
|
||||
|
||||
////////////////////////////////
|
||||
|
||||
@@ -15,65 +15,8 @@ using nlohmann::json;
|
||||
#endif
|
||||
|
||||
#include <fstream>
|
||||
#include <string>
|
||||
#include <vector>
|
||||
#include "make_test_data_available.hpp"
|
||||
|
||||
namespace
|
||||
{
|
||||
// alternating objects and arrays nested `depth` levels deep, with members that
|
||||
// depend on `variant` at some levels, so diffing two variants yields
|
||||
// operations on many levels: replacing the innermost value, adding, removing,
|
||||
// and (for ordered_json) reordering members, and changing array lengths
|
||||
template<typename BasicJsonType>
|
||||
BasicJsonType nested(const std::size_t depth, const int variant)
|
||||
{
|
||||
BasicJsonType value = variant;
|
||||
for (std::size_t i = 0; i < depth; ++i)
|
||||
{
|
||||
if (i % 2 == 0)
|
||||
{
|
||||
BasicJsonType object = BasicJsonType::object();
|
||||
if ((i + static_cast<std::size_t>(variant)) % 7 == 0)
|
||||
{
|
||||
object["x"] = i;
|
||||
}
|
||||
if (variant == 2 && i % 11 == 0)
|
||||
{
|
||||
object["z"] = "z";
|
||||
}
|
||||
object["a"] = std::move(value);
|
||||
if (variant == 1 && i % 5 == 0)
|
||||
{
|
||||
object["y"] = 1;
|
||||
}
|
||||
value = std::move(object);
|
||||
}
|
||||
else
|
||||
{
|
||||
BasicJsonType array = BasicJsonType::array({std::move(value)});
|
||||
if ((i + static_cast<std::size_t>(variant)) % 3 == 0)
|
||||
{
|
||||
array.push_back(i);
|
||||
}
|
||||
value = std::move(array);
|
||||
}
|
||||
}
|
||||
return value;
|
||||
}
|
||||
|
||||
// a path of `depth` reference tokens, as nested() nests its values
|
||||
std::string nested_path(const std::size_t depth)
|
||||
{
|
||||
std::string path;
|
||||
for (std::size_t i = depth; i > 0; --i)
|
||||
{
|
||||
path += (i - 1) % 2 == 0 ? "/a" : "/0";
|
||||
}
|
||||
return path;
|
||||
}
|
||||
} // namespace
|
||||
|
||||
TEST_CASE("JSON patch")
|
||||
{
|
||||
SECTION("examples from RFC 6902")
|
||||
@@ -1809,102 +1752,6 @@ TEST_CASE("JSON patch - diff emits array removals in descending index order")
|
||||
}
|
||||
}
|
||||
|
||||
TEST_CASE("JSON patch: diff of deeply nested values")
|
||||
{
|
||||
SECTION("the diff reproduces the target at every depth")
|
||||
{
|
||||
// depths on either side of the nesting depth up to which diff()
|
||||
// recurses (detail::recursion_depth_limit(), 128); not every depth up
|
||||
// to 300, as the test would then time out under Valgrind
|
||||
std::vector<std::size_t> depths;
|
||||
for (std::size_t depth = 0; depth <= 16; ++depth)
|
||||
{
|
||||
depths.push_back(depth);
|
||||
}
|
||||
for (std::size_t depth = 120; depth <= 136; ++depth)
|
||||
{
|
||||
depths.push_back(depth);
|
||||
}
|
||||
depths.push_back(300);
|
||||
|
||||
for (const auto depth : depths)
|
||||
{
|
||||
CAPTURE(depth);
|
||||
for (int from = 0; from < 3; ++from)
|
||||
{
|
||||
for (int to = 0; to < 3; ++to)
|
||||
{
|
||||
CAPTURE(from);
|
||||
CAPTURE(to);
|
||||
const auto source = nested<json>(depth, from);
|
||||
const auto target = nested<json>(depth, to);
|
||||
const auto patch = json::diff(source, target);
|
||||
CHECK(source.patch(patch) == target);
|
||||
CHECK(patch.empty() == (from == to));
|
||||
|
||||
const auto ordered_source = nested<nlohmann::ordered_json>(depth, from);
|
||||
const auto ordered_target = nested<nlohmann::ordered_json>(depth, to);
|
||||
CHECK(ordered_source.patch(nlohmann::ordered_json::diff(ordered_source, ordered_target)) == ordered_target);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
SECTION("a difference only in the innermost value is one replace operation")
|
||||
{
|
||||
for (std::size_t depth = 0; depth <= 300; ++depth)
|
||||
{
|
||||
CAPTURE(depth);
|
||||
json source = 1;
|
||||
json target = 2;
|
||||
for (std::size_t i = 0; i < depth; ++i)
|
||||
{
|
||||
source = i % 2 == 0 ? json::object({{"a", std::move(source)}}) : json::array({std::move(source)});
|
||||
target = i % 2 == 0 ? json::object({{"a", std::move(target)}}) : json::array({std::move(target)});
|
||||
}
|
||||
CHECK(json::diff(source, target, "/root") == json::array({{{"op", "replace"}, {"path", "/root" + nested_path(depth)}, {"value", 2}}}));
|
||||
}
|
||||
}
|
||||
|
||||
SECTION("values nested too deeply for the call stack (#5393)")
|
||||
{
|
||||
// diff() used to recurse once per nesting level, and compared the
|
||||
// values with operator== on every level. The values are only
|
||||
// parsed and diffed, never copied or compared, since those recurse
|
||||
// too.
|
||||
const std::size_t depth = 100000;
|
||||
for (const bool objects :
|
||||
{
|
||||
false, true
|
||||
})
|
||||
{
|
||||
CAPTURE(objects);
|
||||
std::string source_text;
|
||||
std::string target_text;
|
||||
std::string equal_text;
|
||||
std::string path;
|
||||
for (std::size_t i = 0; i < depth; ++i)
|
||||
{
|
||||
source_text += objects ? "{\"a\":" : "[";
|
||||
path += objects ? "/a" : "/0";
|
||||
}
|
||||
target_text = source_text + "2";
|
||||
equal_text = source_text + "1";
|
||||
source_text += "1";
|
||||
const std::string closing(depth, objects ? '}' : ']');
|
||||
const auto source = json::parse(source_text + closing);
|
||||
|
||||
const auto patch = json::diff(source, json::parse(target_text + closing));
|
||||
REQUIRE(patch.size() == 1);
|
||||
CHECK(patch[0]["op"] == "replace");
|
||||
CHECK(patch[0]["path"] == path);
|
||||
CHECK(patch[0]["value"] == 2);
|
||||
|
||||
CHECK(json::diff(source, json::parse(equal_text + closing)).empty());
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
TEST_CASE("JSON patch - every operation on ordered_json")
|
||||
{
|
||||
using nlohmann::ordered_json;
|
||||
|
||||
@@ -241,6 +241,52 @@ class my_allocator : public std::allocator<T>
|
||||
};
|
||||
};
|
||||
|
||||
/////////////////////////////////////////////////////////////////////
|
||||
// for #3669
|
||||
/////////////////////////////////////////////////////////////////////
|
||||
|
||||
// mimics boost::optional's converting constructor, whose SFINAE check asks
|
||||
// whether T is constructible from const U&
|
||||
template<class T, class Arg>
|
||||
struct issue3669_is_constructible
|
||||
{
|
||||
template<class T2, class A2, class = decltype(T2(std::declval<A2>()))>
|
||||
static char test(int);
|
||||
template<class, class>
|
||||
static long test(...);
|
||||
static constexpr bool value = sizeof(test<T, Arg>(0)) == 1;
|
||||
};
|
||||
|
||||
template<class T>
|
||||
class issue3669_optional
|
||||
{
|
||||
public:
|
||||
issue3669_optional() = default;
|
||||
template<class U>
|
||||
issue3669_optional(const issue3669_optional<U>& /*unused*/, // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
|
||||
typename std::enable_if<issue3669_is_constructible<T, const U&>::value, bool>::type /*unused*/ = true) {}
|
||||
};
|
||||
|
||||
class Issue3669Dummy
|
||||
{
|
||||
public:
|
||||
explicit Issue3669Dummy(const json& /*unused*/) {}
|
||||
};
|
||||
|
||||
class Issue3669Holder
|
||||
{
|
||||
issue3669_optional<Issue3669Dummy> d{};
|
||||
|
||||
// GCC < 11 (C++11/14) rejects a free to_json(json&, const Issue3669Holder&)
|
||||
// here, because ADL for Issue3669Dummy finds it and closes an instantiation
|
||||
// cycle; a hidden friend is only visible to ADL for Issue3669Holder
|
||||
friend void to_json(json& j, const Issue3669Holder& h)
|
||||
{
|
||||
static_cast<void>(h.d); // silence -Wunused-private-field
|
||||
j = "holder";
|
||||
}
|
||||
};
|
||||
|
||||
TEST_CASE("regression tests 2")
|
||||
{
|
||||
SECTION("issue #1001 - Fix memory leak during parser callback")
|
||||
@@ -766,6 +812,14 @@ TEST_CASE("regression tests 2")
|
||||
CHECK(j == k);
|
||||
}
|
||||
|
||||
SECTION("issue #3669 - invalid use of incomplete type with optional member and to_json")
|
||||
{
|
||||
const Issue3669Holder h{};
|
||||
const Issue3669Holder h2(h); // NOLINT(performance-unnecessary-copy-initialization)
|
||||
const json j = h2;
|
||||
CHECK(j == "holder");
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
TEST_CASE("regression test - parser callback must not lose a duplicate key's prior value")
|
||||
|
||||
Reference in New Issue
Block a user